JP4518643B2 - GAME SYSTEM AND INFORMATION STORAGE MEDIUM - Google Patents

Description

ここで、ＵＶＮ座標系のＵ軸及びＶ軸の一方の軸は、各構成点での傷の方向を表す軸であり、Ｕ軸及びＶ軸の他方の軸は上記一方の軸に直交する軸である。そして、上式（３）の（ＵＸ、ＵＹ、ＵＺ）はＵ軸方向の単位ベクトルであり、（ＶＸ、ＶＹ、ＶＺ）はＶ軸方向の単位ベクトルである。また、Ｎ軸は、法線ベクトルの方向に設定された軸であり、上式（３）の（ＮＸ、ＮＹ、ＮＺ）は、Ｎ軸方向の単位ベクトルである。
【００７３】
なお、Ｕ軸、Ｖ軸は互いに直交していなくてもよく、互いに交差する軸であればよい。また、Ｎ軸も、法線ベクトルの方向の軸でなくてもよく、Ｕ軸及びＶ軸に交差する軸であればよい。
【００７４】
（III）次に、図５のＡ２に示すように、ＵＶＮ座標系において反射ベクトルＲＵＶＮ（ＲＵ、ＲＮ、ＲＶ）の方向を変化させて、反射ベクトルＲ２ＵＶＮ（Ｒ２Ｕ、Ｒ２Ｎ、Ｒ２Ｖ）を求める。これは例えば下式（４）により求めることができる。
【００７５】
【数２】

ここで、ＣＵはＵ軸成分でのスケーリング係数であり、ＣＶはＶ軸方向でのスケーリング係数である。
【００７６】
（IV）次に、図５のＡ３に示すように、反射ベクトルＲ２ＵＶＮ（Ｒ２Ｕ、Ｒ２Ｎ、Ｒ２Ｖ）を、ＵＶＮ座標系からワールド座標系に座標変換して、ワールド座標系での反射ベクトルＲ２（Ｒ２Ｘ、Ｒ２Ｙ、Ｒ２Ｚ）を求める。これは例えば下式（５）により求めることができる。
【００７７】
【数３】

以上のように本実施形態では、異方性反射の方向を定義するＵＶＮ座標系を設定し、このＵＶＮ座標系において反射ベクトルＲＵＶＮを変化させて反射ベクトルＲ２ＵＶＮを求めるようにしている。このようにすれば、上式（４）のように、反射ベクトルＲＵＶＮのＵ軸成分ＲＵを係数ＣＵでスケーリングし、Ｖ軸成分ＲＶを係数ＣＶでスケーリングするだけという非常な簡素な処理で、反射ベクトルＲＵＶＮを異方性反射の方向に変化させて反射ベクトルＲ２ＵＶＮを得ることができるようになる。
【００７８】
例えば、Ｕ軸方向に傷の方向を設定する場合には、図６（Ａ）に示すように、Ｕ軸方向のスケーリング係数ＣＵを１．０よりも小さくすればよい。例えば図６（Ａ）では、ＣＵ＝０．５、ＣＶ＝２．０に設定されている。このようにすることで、反射ベクトルは、傷に垂直な方向であるＶ軸の方向に変化し、異方性反射を表現できるようになる。
【００７９】
一方、Ｖ軸方向に傷の方向を設定する場合には、図６（Ｂ）に示すように、Ｖ軸方向のスケーリング係数ＣＶを１．０よりも小さくすればよい。例えば図６（Ｂ）では、ＣＵ＝２．０、ＣＶ＝０．５に設定されている。このようにすることで、反射ベクトルは、傷に垂直な方向であるＵ軸の方向に変化し、異方性反射を表現できるようになる。
【００８０】
なお、スケーリング係数により反射ベクトルの方向を変化させる手法では、反射ベクトルの方向が象限を越えては変化しないことを前提としている。
【００８１】
また、図６（Ａ）、（Ｂ）では、スケーリング係数ＣＵ、ＣＶを用いて反射ベクトルＲＵＶＮの方向を変化させているが、ＲＵＶＮをＮ軸回りで回転させることでＲＵＶＮの方向を変化させる手法を採用してもよい。但し、この手法では、反射ベクトルを回転させる処理や、反射ベクトルの方向が象限を越えて変化しないように制御する処理が必要になるため、処理負荷が重くなるという不利点がある。
【００８２】
これに対して、スケーリング係数で反射ベクトルの方向を変化させる手法では、スケーリング係数を反射ベクトルの各成分に乗算するだけで済むと共に、反射ベクトルの方向が象限を越えて変化しないように制御する処理も不要となるため、処理負荷が非常に軽いという利点がある。
【００８３】
図７（Ａ）は、オブジェクトＯＢに対して、異方性反射の処理を行わずに通常のシェーディング処理を行った場合の生成画像例である。異方性反射の処理を行わない場合には、反射光の強度分布は等方的なものになるため、オブジェクトＯＢの表面には通常形状のハイライトが生じる。
【００８４】
図７（Ｂ）は、従来の楕円体モデルを用いて異方性反射を表現した場合の生成画像例である。図７（Ｂ）では、オブジェクトＯＢの上面に同心円状の傷があると想定されており、ブラシ効果が表現されたハイライト画像が生成されている。
【００８５】
一方、図７（Ｃ）は、本実施形態の手法により異方性反射を表現した場合の生成画像例である。図７（Ｃ）では、図６（Ａ）、（Ｂ）で説明したスケーリング係数がＣＵ＝０．５、ＣＶ＝２．０に設定されている。これにより、オブジェクトＯＢの上面に同心円状の傷がある場合に見えるブラシ効果のハイライト画像を生成できる。
【００８６】
図８（Ａ）は、従来の楕円体モデルを用いて異方性反射を表現した場合の生成画像例である。図８（Ａ）では、オブジェクトＯＢの中心から放射状に傷があると想定されており、ヘアライン効果（髪の毛の天使の輪）が表現されたハイライト画像が生成されている。
【００８７】
一方、図８（Ｂ）は、本実施形態の手法により異方性反射を表現した場合の生成画像例である。図８（Ｂ）では、スケーリング係数がＣＵ＝２．０、ＣＶ＝０．５に設定されている。これにより、オブジェクトＯＢの中心から放射状に傷がある場合に見えるヘアライン効果のハイライト画像を生成できる。
【００８８】
図９（Ａ）〜（Ｄ）、図１０（Ａ）〜（Ｄ）に、スケーリング係数ＣＵ、ＣＶを徐々に変化させた場合に本実施形態により生成されるオブジェクトＯＢの画像の例を示す。
【００８９】
図９（Ａ）では、ＣＵ＝０．５、ＣＶ＝２．０に設定されている。そして、図９（Ｂ）、（Ｃ）、（Ｄ）、図１０（Ａ）、（Ｂ）、（Ｃ）、（Ｄ）では、ＣＵが０．２ずつ増加し、ＣＶが０．２ずつ減少している。図９（Ａ）では、ブラシ効果のハイライト画像が生成され、図１０（Ｄ）ではヘアライン効果のハイライト画像が生成される。
【００９０】
このように本実施形態によれば、スケーリング係数ＣＵ、ＣＶの値を所望の値に変化させるだけで、オブジェクトの表面上に想定する傷の方向を任意に制御でき、ブラシ効果やヘアライン効果などの多様なハイライト画像の生成に成功している。
【００９１】
２．２ 自由曲面の利用
次に、オブジェクトを自由曲面で表す場合について説明する。オブジェクトを自由曲面で表すと、図５で説明したＵＶＮ座標系を簡易な処理で設定することができる。
【００９２】
自由曲面の構成点Ｐｕｖ（ｕ，ｖ）のｘ成分であるＰ^xｕｖ（ｕ，ｖ）は下式（６）のように求められる。
【００９３】
【数４】

Ｐｕｖ（ｕ，ｖ）のｙ成分、ｚ成分についても、上式（６）と同様の式により求めることができる。
【００９４】
なお、有理化を行った場合には下式（７）のようになる。
【００９５】
【数５】

上式（６）、（７）において、Ｑ₀₀〜Ｑ₃₃は制御点である。
【００９６】
またＮｕ_0,4〜Ｎｕ_3,4、Ｎｖ_0,4〜Ｎｖ_3,4は混ぜ合わせ関数である。これらの混ぜ合わせ関数は、下式（８）、（９）の再帰形表現の漸化式（DeBoorCoxの漸化式）と、下式（１０）のノットベクトルＴＵ、ＴＶとに基づき求めることができる。
【００９７】
【数６】

【００９８】
【数７】

ノットベクトルは、パラメータの節目を数値の列として与えるベクトルである。ノットベクトルのノット間隔（ノットベクトルの隣り合う要素間の数値差）が一定である場合には、ユニフォーム（Uniform）と呼ばれ、ノット間隔が一定でない場合は、ノンユニフォーム（Non Uniform）と呼ばれる。
【００９９】
ノンユニフォーム（Non Uniform）で、有理化（Rational）されたＢスプラインが、ＮＵＲＢＳ（Non Uniform Rational B-Spline）である。
【０１００】
図１１に、本実施形態により生成された曲面パッチ２０（自由曲面）の例を示す。
【０１０１】
上式（６）又は（７）から明らかなように、曲面パッチ２０の各構成点は、制御点Ｑ₀₀〜Ｑ₃₃と混ぜ合わせ関数Ｎｕ_0,4〜Ｎｕ_3,4、Ｎｖ_0,4〜Ｎｖ_3,4に基づき求められる。この場合、パラメータｕの変域はｕ₃≦ｕ＜ｕ₄となり、パラメータｖの変域はｖ₃≦ｖ＜ｖ₄になる。
【０１０２】
一方、曲面パッチ２２を生成する場合には、使用する制御点のセットが、Ｑ₀₀〜Ｑ₃₃からＱ₀₁〜Ｑ₃₄に変わる。そして、曲面パッチ２２の各構成点は、制御点Ｑ₀₁〜Ｑ₃₄と混ぜ合わせ関数Ｎｕ_1,4〜Ｎｕ_4,4、Ｎｖ_0,4〜Ｎｖ_3,4に基づき求められる。この場合、パラメータｕの変域はｕ₄≦ｕ＜ｕ₅となり、パラメータｖの変域はｖ₃≦ｖ＜ｖ₄になる。
【０１０３】
本実施形態により生成された曲面パッチ２０の各構成点は、ポリゴンの頂点に設定され、これらの頂点により構成されるポリゴンが画面上に表示されることになる。
【０１０４】
図１２に、自由曲面（ＮＵＲＢＳ）で表されたオブジェクトＯＢ（ワイヤーフレーム表示）の画像の例を示す。曲面の分割数を制御することで、オブジェクトＯＢの精密度を変化させることができる。
【０１０５】
さて、オブジェクトを自由曲面で表した場合には、曲面の接線（傾き）ベクトルを簡易に求めることができる。
【０１０６】
例えば、図１３において、構成点Ｐでのｕ方向の接線ベクトルＵＶＥＣのｘ成分は下式（１１）の計算を行うことで求めることができる。ｙ成分、ｚ成分も同様である。
【０１０７】
【数８】

また、ｖ方向の接線ベクトルＶＶＥＣのｘ成分は下式（１２）の計算を行うことで求めることができる。ｙ成分、ｚ成分も同様である。
【０１０８】
【数９】

なお、上式(１２)、(１３)は有理化を行わない場合の式であるが、有理化を行う場合も同様にして求めることができる。
【０１０９】
また、上式（１２）、（１３）により求められた接線ベクトルＵＶＥＣ、ＶＶＥＣの外積を計算することで、図１３に示すように、構成点Ｐでの法線ベクトルＮを求めることができる。
【０１１０】
そして、接線ベクトルＵＶＥＣの方向に図５で説明したＵＶＮ座標系のＵ軸を設定し、接線ベクトルＶＶＥＣの方向にＵＶＮ座標系のＶ軸を設定し、法線ベクトルＮの方向にＵＶＮ座標系のＮ軸を設定する。
【０１１１】
このようにすれば、オブジェクトの各構成点に対して図５に示すようなＵＶＮ座標系を設定できる。そして、この各構成点に設定されたＵＶＮ座標系において図５のＡ２に示すように反射ベクトルの方向を変化させれば、異方性反射を表現できるようになる。
【０１１２】
このように、オブジェクトを自由曲面を表した場合には、反射ベクトルを変化させるＵＶＮ座標系を、比較的簡易な処理で設定できるという利点がある。
【０１１３】
また、法線ベクトルＮを得るために求める接線ベクトルＵＶＥＣ、ＶＶＥＣを、ＵＶＮ座標系の設定処理のために有効利用できるようになり、処理の効率化を図れる。
【０１１４】
なお、オブジェクトをポリゴンで表現した場合にも、例えば以下に述べるような手法でＵＶＮ座標系を設定できる。
【０１１５】
例えば図１４（Ａ）では、オブジェクトＯＢ（ＯＢ１、ＯＢ２又はＯＢ３）のローカル座標系（ＸＬ、ＹＬ、ＺＬ）において、ＹＬ軸を中心としオブジェクトＯＢの各構成点（頂点）を通る円を想定し、この円の接線ベクトルＵＶＥＣの方向にＵ軸を設定する。そして、この接線ベクトルＵＶＥＣと各構成点に付与されている法線ベクトルとの外積を計算することでＶ軸の方向を求める。このようにすることで、オブジェクトＯＢの各構成点（頂点）に対してＵＶＮ座標系を設定できるようになる。
【０１１６】
そしてこの手法によれば、図１４（Ｂ）に示すように、一定方向（接線ベクトルＵＶＥＣの方向又はＵＶＥＣに垂直な方向）に傷がついた金属板等での異方性反射を表現できるようになる。
【０１１７】
２．３ スペキュラーマッピング
さて図４（Ｂ）や上式（５）で得られた反射ベクトルＲ２を用い行うシェーディング演算は、いわゆるスペキュラーマッピングにより実現することが望ましい。反射ベクトルＲ２と視線ベクトルのなす角度により鏡面反射の強度を計算するフォンのモデル等では、スペキュラー形状（ハイライト形状）がポリゴン（広義にはプリミティブ面）形状の影響を受けて不自然な形になるという問題が生じる場合があるからである。
【０１１８】
しかしながら、前述した大平や高木・横井のモデルでは、スカラー量である鏡面反射光の強度が計算結果として出力される。従って、スペキュラー形状がポリゴン形状の影響で不自然な形になるという問題を、いわゆるスペキュラーマッピングの手法により解決できない。
【０１１９】
この場合、ノンリアルタイム処理のＣＧのようにピクセル単位で鏡面反射光の強度を計算すれば、スペキュラー形状がポリゴン形状に依存してしまうという問題を解決できる。しかしながら、この解決手法は、リアルタイム処理が要求されるゲームシステムにおいては非現実的である。
【０１２０】
これに対して本実施形態では、スカラー量ではなく、反射ベクトルＲ２が上式（５）のように求められる。従って、この反射ベクトルＲ２に基づいてテクスチャ座標を求め、このテクスチャ座標に基づいてスペキュラー表現テクスチャをオブジェクトにマッピングするようにすれば、スペキュラーマッピングを実現できるようになる。
【０１２１】
より具体的には例えば図１５（Ａ）に示すようなスペキュラー表現テクスチャを用意する。なお、このスペキュラー表現テクスチャはリアルタイムに生成してもよい。
【０１２２】
図１５（Ａ）に示すスペキュラー表現テクスチャでは、その中心に例えば白いハイライト（光源）画像が描かれており、中心から周囲に向かうにつれてその輝度が徐々に減衰し、黒に変化して行く。なお、後述する最終的な極座標変換の後のハイライト画像が所望の適切な形状になるように、スペキュラー表現テクスチャに描かれるハイライト画像の形状を変形しておくことが望ましい。
【０１２３】
この図１５（Ａ）に示すスペキュラー表現テクスチャにより、図１５（Ｂ）に示すような仮想球３０を想定する。
【０１２４】
そして図１６に示すように、オブジェクトＯＢを内包するように仮想球３０を設定する。次に、光源ベクトルＬに基づき構成点Ｐでの反射ベクトルを求め、この反射ベクトルから、本実施形態の手法で、異方性反射を考慮した反射ベクトルＲ２を求める。そして、この反射ベクトルＲ２と仮想球３０との交点ＰＲを求めることで、スペキュラー表現テクスチャのテクスチャ座標ＴＸ、ＴＹ（コーディネート値）を求め、これらのＴＸ、ＴＹを構成点Ｐに設定する。
【０１２５】
そして、このようにして各構成点に設定されたテクスチャ座標ＴＸ、ＴＹに基づいて、図１５（Ａ）に示すスペキュラー表現テクスチャをオブジェクトＯＢにマッピングして、スペキュラーマッピングを実現する。
【０１２６】
以上のようにすれば、スペキュラー形状（ハイライト形状）がポリゴン形状の影響を受けないようになるため、より自然でリアルな画像を生成できるようになる。
【０１２７】
３．本実施形態の処理
次に、本実施形態の処理の詳細例について、図１７、図１８のフローチャートを用いて説明する。
【０１２８】
まずＰＮ（構成点の番号）を０に設定する（ステップＳ１）。
【０１２９】
次に、構成点（頂点）ＰＮでの接線ベクトルＵＶＥＣ、ＶＶＥＣを上式（１１）、（１２）などに基づいて求める（ステップＳ２）。
【０１３０】
次に、図１３で説明したように、接線ベクトルＵＶＥＣ、ＶＶＥＣの外積計算を行い、法線ベクトルＮを求める（ステップＳ３）。
【０１３１】
次に、光源情報、構成点ＰＮの位置、構成点ＰＮでの法線ベクトルＮに基づき反射ベクトルＲを求める（ステップＳ４）。例えば点光源の場合には、光源位置と構成点ＰＮの位置とを結ぶベクトルを図４（Ａ）の光源ベクトルＬとして求め、この光源ベクトルＬと法線ベクトルＮとに基づき反射ベクトルＲを求める。一方、平行光源の場合には、平行光源からの光源ベクトルＬと法線ベクトルＮとに基づき反射ベクトルＲを求める。
【０１３２】
次に、図５のＡ１で説明したように、ワールド座標系からＵＶＮ座標系（ＵＶＥＣ、ＶＶＥＣ、Ｎで構成される座標系）に反射ベクトルＲを座標変換し、ＲＵＶＮを求める（ステップＳ５）。
【０１３３】
次に、図５のＡ２で説明したように、ＵＶＮ座標系においてＲＵＶＮに対して、異方性反射の方向を表す係数ＣＵ、ＣＶに基づくスケーリング計算を行い、反射ベクトルＲ２ＵＶＮを求める（ステップＳ６）。
【０１３４】
次に、図５のＡ３で説明しように、Ｒ２ＵＶＮをワールド座標系に座標変換し、反射ベクトルＲ２を求める（ステップＳ７）。
【０１３５】
次に、Ｒ２と視線ベクトルとのなす角度θに基づき、例えばＰ_S×ＣＯＳⁿθの計算を行い、構成点ＰＮでの鏡面反射光の強度を求める（ステップＳ８）。
【０１３６】
次に、ＰＮがＰＥＮＤよりも大きいか否かを判断し、ＰＥＮＤよりも小さい場合には、ＰＮを１だけインクリメントし（ステップＳ１０）、ステップＳ２に戻る。一方、ＰＥＮＤよりも大きい場合には処理を終了する。
【０１３７】
図１８は、スペキュラーマッピングを行う場合のフローチャートである。スペキュラーマッピングを行う場合には、図１７のステップＳ８において図１８の処理を行うことになる。
【０１３８】
まず、オブジェクトの中心を仮想球の中心に設定した場合に、オブジェクトの中心と仮想球上のハイライト画像の中心（マップの中心）とを結ぶ方向を、視線ベクトルの方向に一致させるマトリクスＭを求める（ステップＳ１１）。
【０１３９】
即ち図１９（Ａ）に示すように、その中心がオブジェクトＯＢの中心と一致するような仮想球３０を想定する。そして、例えばオブジェクトに設定されたＸＹＺ座標系（各構成点に設定してもよい）において視点ＶＰの方へと向かう視線ベクトルをＥとした場合に、図１９（Ｂ）、（Ｃ）に示すように、視線ベクトルＥ’の方向がＸ’軸の負側方向に向くようなＸ’Ｙ’Ｚ’座標系を想定する。すると、上記のマトリクスＭは、下式（１３）のように、視線ベクトルＥ’をＥに変換するマトリクスとなる。
【０１４０】
Ｅ＝Ｍ×Ｅ’ （１３）
上式（１３）より、
Ｅ’＝Ｍ^-1×Ｅ （１４）
となる。上式（１４）において、Ｍ^-1はＭの逆変換マトリクスである。
【０１４１】
そして、この逆変換マトリクスＭ^-1に基づいて下式（１５）のように反射ベクトルＲ２を変換して、反射ベクトルＲ２’を求める（ステップＳ１２）。
【０１４２】
Ｒ２’＝Ｍ^-1×Ｒ２ （１５）
次に、図１９（Ｄ）に示すように、反射ベクトルＲ２’を極座標変換して、テクスチャ座標ＴＸ、ＴＹを求める（ステップＳ１３）。
【０１４３】
即ち、図１９（Ｄ）に示すように、反射ベクトルＲ２’をＸ’Ｚ’平面に投影したベクトルをＲ２”とし、Ｒ２”とＸ’軸とのなす角度をθ１（度）とする。また反射ベクトルＲ２’とＹ’軸のなす角度をθ２（度）とする。この場合に、下式（１６）のようにしてテクスチャ座標ＴＸ、ＴＹを求めることができる。
【０１４４】
ＴＸ＝θ１／３６０
ＴＹ＝θ２／１８０ （１６）
例えば上式（１６）において、θ１＝１８０（度）、θ２＝９０（度）とした場合には、図１９（Ｄ）から明らかなように、反射ベクトルＲ２’の方向と視線ベクトルＥ’の方向とが一致する。そして、この時のテクスチャ座標は、ＴＸ＝０．５、ＴＹ＝０．５となり、スペキュラー表現テクスチャのハイライト画像の中心（マップの中心）が参照されることになる。即ち、上式（１５）の変換は、反射ベクトルの方向が視線ベクトルの方向に一致した場合に、スペキュラー表現テクスチャのハイライト画像の中心が参照されるような変換であるということができる。
【０１４５】
最後に、求められたテクスチャ座標ＴＸ、ＴＹを構成点ＰＮ（頂点）に付与する（ステップＳ１４）。このテクスチャ座標ＴＸ、ＴＹを用いて、図１５（Ａ）に示すようなスペキュラー表現テクスチャをオブジェクトＯＢにマッピングすることで、いわゆるスペキュラーマッピングを実現できる。
【０１４６】
４．ハードウェア構成
次に、本実施形態を実現できるハードウェアの構成の一例について図２０を用いて説明する。
【０１４７】
メインプロセッサ９００は、ＣＤ９８２（情報記憶媒体）に格納されたプログラム、通信インターフェース９９０を介して転送されたプログラム、或いはＲＯＭ９５０（情報記憶媒体の１つ）に格納されたプログラムなどに基づき動作し、ゲーム処理、画像処理、音処理などの種々の処理を実行する。
【０１４８】
コプロセッサ９０２は、メインプロセッサ９００の処理を補助するものであり、高速並列演算が可能な積和算器や除算器を有し、マトリクス演算（ベクトル演算）を高速に実行する。例えば、オブジェクトを移動させたり動作（モーション）させるための物理シミュレーションに、マトリクス演算などの処理が必要な場合には、メインプロセッサ９００上で動作するプログラムが、その処理をコプロセッサ９０２に指示（依頼）する。
【０１４９】
ジオメトリプロセッサ９０４は、座標変換、透視変換、光源計算、曲面生成などのジオメトリ処理を行うものであり、高速並列演算が可能な積和算器や除算器を有し、マトリクス演算（ベクトル演算）を高速に実行する。例えば、座標変換、透視変換、光源計算などの処理を行う場合には、メインプロセッサ９００で動作するプログラムが、その処理をジオメトリプロセッサ９０４に指示する。
【０１５０】
データ伸張プロセッサ９０６は、圧縮された画像データや音データを伸張するデコード処理を行ったり、メインプロセッサ９００のデコード処理をアクセレートする処理を行う。これにより、オープニング画面、インターミッション画面、エンディング画面、或いはゲーム画面などにおいて、ＭＰＥＧ方式等で圧縮された動画像を表示できるようになる。なお、デコード処理の対象となる画像データや音データは、ＲＯＭ９５０、ＣＤ９８２に格納されたり、或いは通信インターフェース９９０を介して外部から転送される。
【０１５１】
描画プロセッサ９１０は、ポリゴンや曲面などのプリミティブ面で構成されるオブジェクトの描画（レンダリング）処理を高速に実行するものである。オブジェクトの描画の際には、メインプロセッサ９００は、ＤＭＡコントローラ９７０の機能を利用して、オブジェクトデータを描画プロセッサ９１０に渡すと共に、必要であればテクスチャ記憶部９２４にテクスチャを転送する。すると、描画プロセッサ９１０は、これらのオブジェクトデータやテクスチャに基づいて、Ｚバッファなどを利用した陰面消去を行いながら、オブジェクトをフレームバッファ９２２に高速に描画する。また、描画プロセッサ９１０は、αブレンディング（半透明処理）、デプスキューイング、ミップマッピング、フォグ処理、バイリニア・フィルタリング、トライリニア・フィルタリング、アンチエリアシング、シェーディング処理なども行うことができる。そして、１フレーム分の画像がフレームバッファ９２２に書き込まれると、その画像はディスプレイ９１２に表示される。
【０１５２】
サウンドプロセッサ９３０は、多チャンネルのＡＤＰＣＭ音源などを内蔵し、ＢＧＭ、効果音、音声などの高品位のゲーム音を生成する。生成されたゲーム音は、スピーカ９３２から出力される。
【０１５３】
ゲームコントローラ９４２からの操作データや、メモリカード９４４からのセーブデータ、個人データは、シリアルインターフェース９４０を介してデータ転送される。
【０１５４】
ＲＯＭ９５０にはシステムプログラムなどが格納される。なお、業務用ゲームシステムの場合には、ＲＯＭ９５０が情報記憶媒体として機能し、ＲＯＭ９５０に各種プログラムが格納されることになる。なお、ＲＯＭ９５０の代わりにハードディスクを利用するようにしてもよい。
【０１５５】
ＲＡＭ９６０は、各種プロセッサの作業領域として用いられる。
【０１５６】
ＤＭＡコントローラ９７０は、プロセッサ、メモリ（ＲＡＭ、ＶＲＡＭ、ＲＯＭ等）間でのＤＭＡ転送を制御するものである。
【０１５７】
ＣＤドライブ９８０は、プログラム、画像データ、或いは音データなどが格納されるＣＤ９８２（情報記憶媒体）を駆動し、これらのプログラム、データへのアクセスを可能にする。
【０１５８】
通信インターフェース９９０は、ネットワークを介して外部との間でデータ転送を行うためのインターフェースである。この場合に、通信インターフェース９９０に接続されるネットワークとしては、通信回線（アナログ電話回線、ＩＳＤＮ）、高速シリアルバスなどを考えることができる。そして、通信回線を利用することでインターネットを介したデータ転送が可能になる。また、高速シリアルバスを利用することで、他のゲームシステムとの間でのデータ転送が可能になる。
【０１５９】
なお、本発明の各手段は、その全てを、ハードウェアのみにより実行してもよいし、情報記憶媒体に格納されるプログラムや通信インターフェースを介して配信されるプログラムのみにより実行してもよい。或いは、ハードウェアとプログラムの両方により実行してもよい。
【０１６０】
そして、本発明の各手段をハードウェアとプログラムの両方により実行する場合には、情報記憶媒体には、本発明の各手段をハードウェアを利用して実行するためのプログラムが格納されることになる。より具体的には、上記プログラムが、ハードウェアである各プロセッサ９０２、９０４、９０６、９１０、９３０等に処理を指示すると共に、必要であればデータを渡す。そして、各プロセッサ９０２、９０４、９０６、９１０、９３０等は、その指示と渡されたデータとに基づいて、本発明の各手段を実行することになる。
【０１６１】
図２１（Ａ）に、本実施形態を業務用ゲームシステムに適用した場合の例を示す。プレーヤは、ディスプレイ１１００上に映し出されたゲーム画像を見ながら、レバー１１０２、ボタン１１０４等を操作してゲームを楽しむ。内蔵されるシステムボード（サーキットボード）１１０６には、各種プロセッサ、各種メモリなどが実装される。そして、本発明の各手段を実行するための情報（プログラム又はデータ）は、システムボード１１０６上の情報記憶媒体であるメモリ１１０８に格納される。以下、この情報を格納情報と呼ぶ。
【０１６２】
図２１（Ｂ）に、本実施形態を家庭用のゲームシステムに適用した場合の例を示す。プレーヤはディスプレイ１２００に映し出されたゲーム画像を見ながら、ゲームコントローラ１２０２、１２０４を操作してゲームを楽しむ。この場合、上記格納情報は、本体システムに着脱自在な情報記憶媒体であるＣＤ１２０６、或いはメモリカード１２０８、１２０９等に格納されている。
【０１６３】
図２１（Ｃ）に、ホスト装置１３００と、このホスト装置１３００とネットワーク１３０２（ＬＡＮのような小規模ネットワークや、インターネットのような広域ネットワーク）を介して接続される端末１３０４-1〜１３０４-n（ゲーム機、携帯電話）とを含むシステムに本実施形態を適用した場合の例を示す。この場合、上記格納情報は、例えばホスト装置１３００が制御可能な磁気ディスク装置、磁気テープ装置、メモリ等の情報記憶媒体１３０６に格納されている。端末１３０４-1〜１３０４-nが、スタンドアロンでゲーム画像、ゲーム音を生成できるものである場合には、ホスト装置１３００からは、ゲーム画像、ゲーム音を生成するためのゲームプログラム等が端末１３０４-1〜１３０４-nに配送される。一方、スタンドアロンで生成できない場合には、ホスト装置１３００がゲーム画像、ゲーム音を生成し、これを端末１３０４-1〜１３０４-nに伝送し端末において出力することになる。
【０１６４】
なお、図２１（Ｃ）の構成の場合に、本発明の各手段を、ホスト装置（サーバー）と端末とで分散して実行するようにしてもよい。また、本発明の各手段を実行するための上記格納情報を、ホスト装置（サーバー）の情報記憶媒体と端末の情報記憶媒体に分散して格納するようにしてもよい。
【０１６５】
またネットワークに接続する端末は、家庭用ゲームシステムであってもよいし業務用ゲームシステムであってもよい。そして、業務用ゲームシステムをネットワークに接続する場合には、業務用ゲームシステムとの間で情報のやり取りが可能であると共に家庭用ゲームシステムとの間でも情報のやり取りが可能なセーブ用情報記憶装置（メモリカード、携帯型ゲーム装置）を用いることが望ましい。
【０１６６】
なお本発明は、上記実施形態で説明したものに限らず、種々の変形実施が可能である。
【０１６７】
例えば、本発明のうち従属請求項に係る発明においては、従属先の請求項の構成要件の一部を省略する構成とすることもできる。また、本発明の１の独立請求項に係る発明の要部を、他の独立請求項に従属させることもできる。
【０１６８】
また反射ベクトルの方向を変化させる手法としては、処理の簡素化の観点からは図５で説明した手法が特に望ましいが、本発明はこれに限定されず種々の変形実施が可能である。
【０１６９】
また第２の座標系の設定手法も、図１３や図１４（Ａ）、（Ｂ）で説明した手法に限定されるものではない。
【０１７０】
また、シェーディング演算により得られた鏡面反射光の強度（輝度）をα値（各ピクセルに関連づけられて記憶される情報であり色情報以外のプラスアルファの情報）に設定し、このα値に基づいてα合成（αブレンディング、α加算）を行い、例えばガラス表面上の傷で反射光が異方性反射する様子を表現してもよい。
【０１７１】
また、本発明は種々のゲーム（格闘ゲーム、シューティングゲーム、ロボット対戦ゲーム、スポーツゲーム、競争ゲーム、ロールプレイングゲーム、音楽演奏ゲーム、ダンスゲーム等）に適用できる。
【０１７２】
また本発明は、業務用ゲームシステム、家庭用ゲームシステム、多数のプレーヤが参加する大型アトラクションシステム、シミュレータ、マルチメディア端末、ゲーム画像を生成するシステムボード等の種々のゲームシステム（画像生成システム）に適用できる。
【図面の簡単な説明】
【図１】図１（Ａ）、（Ｂ）は、異方性反射について説明するための図である。
【図２】図２（Ａ）、（Ｂ）は、楕円体モデルを用いて異方性反射を実現する手法について説明するための図である。
【図３】本実施形態のゲームシステムの機能ブロック図の例である。
【図４】図４（Ａ）、（Ｂ）は、反射ベクトルの方向を変化させて異方性反射を実現する手法について説明するための図である。
【図５】ＵＶＮ座標系で反射ベクトルの方向を変化させて異方性反射を実現する手法について説明するための図である。
【図６】図６（Ａ）、（Ｂ）は、スケーリング係数を用いて反射ベクトルの方向を変化させる手法について説明するための図である。
【図７】図７（Ａ）はノーマルシェーディングの場合、図７（Ｂ）は楕円体モデルを用いた場合、図７（Ｃ）は本実施形態の手法を用いた場合の生成画像例である。
【図８】図８（Ａ）は楕円体モデルを用いた場合、図８（Ｂ）は本実施形態の手法を用いた場合の生成画像例である。
【図９】図９（Ａ）、（Ｂ）、（Ｃ）、（Ｄ）は、スケーリング係数を徐々に変化させた場合の生成画像例である。
【図１０】図１０（Ａ）、（Ｂ）、（Ｃ）、（Ｄ）も、スケーリング係数を徐々に変化させた場合の生成画像例である。
【図１１】オブジェクトを自由曲面で表現する手法について説明するための図である。
【図１２】オブジェクトを自由曲面で表現する手法について説明するための図である。
【図１３】各構成点での接線ベクトルを求めて、ＵＶＮ座標系を設定する手法について説明するための図である。
【図１４】図１４（Ａ）、（Ｂ）は、オブジェクトがポリゴンで表現される場合におけるＵＶＮ座標系の設定手法について説明するための図である。
【図１５】図１５（Ａ）、（Ｂ）は、スペキュラー表現テクスチャと仮想球について説明するための図である。
【図１６】スペキュラーマッピングについて説明するための図である。
【図１７】本実施形態の処理の詳細例について示すフローチャートである。
【図１８】本実施形態の処理の詳細例について示すフローチャートである。
【図１９】図１９（Ａ）、（Ｂ）、（Ｃ）、（Ｄ）は、スペキュラー表現テクスチャのテクスチャ座標の求め方について説明するための図である。
【図２０】本実施形態を実現できるハードウェアの構成の一例を示す図である。
【図２１】図２１（Ａ）、（Ｂ）、（Ｃ）は、本実施形態が適用される種々の形態のシステムの例を示す図である。
【符号の説明】
ＯＢ オブジェクト
ＬＳ 光源
ＶＰ 視点
Ｌ 光源ベクトル
Ｎ 法線ベクトル
Ｒ、Ｒ２、ＲＵＶＮ、Ｒ２ＵＶＮ 反射ベクトル
２０、２２ 曲面パッチ
３０ 仮想球
１００ 処理部
１１０ 反射ベクトル演算部
１１２ 反射ベクトル変化部
１１４ シェーディング演算部
１３０ 描画部
１３２ テクスチャマッピング部
１６０ 操作部
１７０ 記憶部
１７２ 主記憶部
１７４ 描画領域
１７６ テクスチャ記憶部
１８０ 情報記憶媒体
１９０ 表示部
１９２ 音出力部
１９４ 携帯型情報記憶装置
１９６ 通信部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a game system and an information storage medium.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, a game system that generates an image that can be seen from a given viewpoint in an object space that is a virtual three-dimensional space is known, and is popular as a device that can experience so-called virtual reality. Taking a game system in which a racing game can be enjoyed as an example, a player operates a car (object) to run in an object space, and competes with other players and cars operated by a computer to play a three-dimensional game. Enjoy.
[0003]
Now, in such a game system, it is an important technical problem to generate a more realistic and high-quality image in order to improve the virtual reality of the player. For this reason, it is desirable that the specular reflection (specular) on the surface of the object can be expressed more realistically.
[0004]
As a method for realizing such specular reflection, models such as Phong and Blinn are conventionally known. However, these models are all isotropic reflection models, and the intensity distribution of reflected light is isotropic.
[0005]
On the other hand, when there is a scratch in a certain direction on the surface of the object, a phenomenon occurs in which reflected light is strongly reflected in a specific direction due to the scratch. For example, a phenomenon in which a light and dark pattern peculiar to a knob of an audio device having concentric scratches can be seen, or an “angel's ring” can be seen in human hair.
[0006]
In order to express such a specific light-dark pattern, a so-called anisotropic reflection model is required. For example, a conventional example of such an anisotropic reflection model is disclosed in "" Analysis of anisotropic reflection model ", Takagi, Yokoi et al., Graphics and CAD, 11-1, 1983.10.17. Yes.
[0007]
For example, it is assumed that there is a scratch as shown in FIG. When the portion of the point P in FIG. 1A is viewed locally, it is as shown in FIG. Here, the normal vector perpendicular to the surface is N, the vector horizontal to the flaw is U, and the vector perpendicular to the flaw is V. Also, let R be the reflection vector at point P of the light source vector L from the light source LS. At this time, the reflection vector R is expressed by the following equation (1).
[0008]
R = 2 (N · L) N−L (1)
In a general reflection model, the intensity (luminance) of specular reflection light (specular component) is determined based on the angle formed by the reflection vector R and the line-of-sight vector obtained by the above equation (1).
[0009]
The specular reflected light itself is modeled by the intensity distribution of a flat ellipsoid is the Ohira model shown in FIG. That is, the intensity of the specular reflection light is obtained based on the length DE up to the point where the line-of-sight vector E intersects the ellipsoid ELP.
[0010]
On the other hand, in the Takagi / Yokoi model shown in FIG. 2 (B), an anisotropy is given to Bryn's minute plane model, and the distribution of the minute plane is solved by an ellipsoidal model.
[0011]
However, since the Ohira, Takagi, and Yokoi models use an ellipsoidal model, a large amount of processing time is required to calculate the intensity of the specular reflection light. Therefore, this model is not suitable for a game system that requires real-time processing.
[0012]
In the Ohira, Takagi, and Yokoi models, the intensity of specular reflected light, which is a scalar quantity, is output as a calculation result. Therefore, the problem that the specular shape (highlight shape) becomes unnatural due to the influence of the polygon shape cannot be solved by using a so-called specular mapping method.
[0013]
In this case, if the intensity of specular reflection light is calculated in units of pixels as in non-real-time processing CG (Computer Graphics), the above problem can be solved. However, this causes a problem of further increase in processing time.
[0014]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a game system and an information storage medium that can realize the expression of anisotropic reflection with a small processing load. .
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a game system for generating an image, a unit for obtaining a reflection vector at each constituent point of an object based on light source information and normal information, Characterized in that it includes means for obtaining a second reflection vector by changing the direction to the direction of anisotropic reflection, and means for performing a shading operation of the object based on the second reflection vector and viewpoint information. To do. The information storage medium according to the present invention is an information storage medium that can be used by a computer, and includes a program for executing the above means. The program according to the present invention is a program (including a program embodied in a carrier wave) that can be used by a computer, and includes a processing routine for executing the above means.
[0016]
According to the present invention, based on light source information (eg, light source vector, light source position) and normal information (eg, normal vector, information indicating the direction of a surface), each component point (eg, vertex, primitive point) of the object. Is obtained. Then, by changing this reflection vector in the direction of anisotropic reflection (for example, in a case where the object is assumed to have a flaw or the like, the second reflection vector is changed to a direction perpendicular to the flaw). Desired. Then, an object shading calculation is performed using the second reflection vector.
[0017]
In this way, according to the present invention, anisotropic reflection can be expressed by a calculation process with very little load compared to the conventional method using an ellipsoidal model. Therefore, it is possible to construct an anisotropic reflection model that is optimal for a game system that requires real-time processing.
[0018]
In addition, the game system, information storage medium, and program according to the present invention perform coordinate conversion of the reflection vector into a second coordinate system that defines the direction of anisotropic reflection, and the reflection vector of the reflection vector is converted in the second coordinate system. The direction is changed to obtain the second reflection vector, the second reflection vector in the second coordinate system is transformed into the first coordinate system, and the second reflection vector in the first coordinate system is transformed. The object shading calculation is performed based on the reflection vector of 2.
[0019]
In this way, for example, in the second coordinate system set for each constituent point, the direction of the reflection vector can be changed by a uniform process, and the process can be simplified.
[0020]
In the game system, information storage medium, and program according to the present invention, the second coordinate system has a first axis that represents the direction of anisotropic reflection and a second axis that intersects the first axis. In this case, the second reflection vector is obtained by changing the direction of the reflection vector in the second coordinate system to one of the first and second axes.
[0021]
In this way, for example, in the second coordinate system set at each constituent point, the anisotropy can be achieved by a simple process of changing the direction of the reflection vector to one of the first and second axes. Reflection can be expressed.
[0022]
Note that the direction of the flaw assumed on the surface of the object may be either the first or second axis.
[0023]
In the game system, information storage medium, and program according to the present invention, the second coordinate system has a first axis that represents the direction of anisotropic reflection and a second axis that intersects the first axis. In the case, the component of the first axis of the reflection vector in the second coordinate system is scaled by a first coefficient and the second axis of the reflection vector in the second coordinate system is scaled. The second reflection vector is obtained by scaling the component by a second coefficient.
[0024]
In this way, the second reflection vector can be obtained by a simple process of simply scaling the components of the first and second axes of the reflection vector by the first and second coefficients, and the processing load is reduced. It can be greatly reduced.
[0025]
In the game system, information storage medium, and program according to the present invention, the second coordinate system has a first axis that represents the direction of anisotropic reflection and a second axis that intersects the first axis. When the object is represented by a free-form surface, the first and second axes are set in the directions of the first and second tangent vectors at each constituent point of the free-form surface.
[0026]
In this way, the second coordinate system can be set only by obtaining the first and second tangent vectors at each constituent point of the free-form surface by a given calculation formula. The setting process can be simplified. Also, the tangent vector that needs to be obtained in order to obtain the normal vector can be effectively used for the setting process of the second coordinate system, and the processing efficiency can be improved.
[0027]
In the game system, information storage medium, and program according to the present invention, a normal vector serving as the normal information is obtained based on the first and second tangent vectors, and the second vector is oriented in the direction of the normal vector. A third axis of the coordinate system is set.
[0028]
In this way, the reflection vector can be obtained using the normal vector as normal information, and the tangent vector obtained for obtaining the normal vector is set in the second coordinate system. Therefore, it is possible to improve the processing efficiency.
[0029]
The game system, information storage medium, and program according to the present invention determine a texture coordinate of a specular expression texture based on the second reflection vector, and map the specular expression texture to an object based on the determined texture coordinate. It is characterized by that.
[0030]
In this way, the problem that the specular shape (highlight shape) becomes an unnatural shape due to the influence of the shape of the primitive surface (polygon or the like) can be effectively solved.
[0031]
In the game system, information storage medium, and program according to the present invention, the center of the highlight image drawn on the specular expression texture is referred to when the direction of the second reflection vector coincides with the direction of the line-of-sight vector. Transformation is performed on the second reflection vector to obtain the texture coordinates.
[0032]
In this way, texture coordinates for referring to the specular expression texture can be obtained by simple processing.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0034]
1. Constitution
FIG. 3 shows an example of a functional block diagram of the game system (image generation system) of the present embodiment. In this figure, the present embodiment only needs to include at least the processing unit 100 (or include the processing unit 100 and the storage unit 170), and the other blocks can be optional components.
[0035]
The operation unit 160 is for a player to input operation data, and the function can be realized by hardware such as a lever, a button, a microphone, or a housing.
[0036]
The storage unit 170 serves as a work area such as the processing unit 100 or the communication unit 196, and its function can be realized by hardware such as a RAM.
[0037]
An information storage medium (storage medium usable by a computer) 180 stores information such as programs and data, and functions thereof are an optical disk (CD, DVD), a magneto-optical disk (MO), a magnetic disk, and a hard disk. It can be realized by hardware such as a magnetic tape or a memory (ROM). The processing unit 100 performs various processes of the present invention (this embodiment) based on information stored in the information storage medium 180. That is, the information storage medium 180 stores information (program or data) for executing the means of the present invention (this embodiment) (particularly, the blocks included in the processing unit 100).
[0038]
Part or all of the information stored in the information storage medium 180 is transferred to the storage unit 170 when the system is powered on. The information storage medium 180 also includes a program for performing the processing of the present invention, image data, sound data, shape data of the display object, information for instructing the processing of the present invention, or processing in accordance with the instructions. Information etc. can be included.
[0039]
The display unit 190 outputs an image generated according to the present embodiment, and the function thereof can be realized by hardware such as a CRT, LCD, or HMD (head mounted display).
[0040]
The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by hardware such as a speaker.
[0041]
The portable information storage device 194 stores player personal data, game save data, and the like. As the portable information storage device 194, a memory card, a portable game device, and the like can be considered.
[0042]
The communication unit 196 performs various controls for communicating with the outside (for example, a host device or other game system), and functions thereof are various processors, hardware such as a communication ASIC, It can be realized by a program.
[0043]
The program or data for executing the means of the present invention (this embodiment) may be distributed from the information storage medium of the host device (server) to the information storage medium 180 via the network and the communication unit 196. Good. Use of such an information storage medium of the host device (server) is also included in the scope of the present invention.
[0044]
The processing unit 100 (processor) performs various processing such as game processing, image generation processing, or sound generation processing based on operation data, a program, and the like from the operation unit 160. The function of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.) or ASIC (gate array, etc.) and a given program (game program).
[0045]
Here, game processing performed by the processing unit 100 includes coin (price) acceptance processing, various mode setting processing, game progress processing, selection screen setting processing, position of an object (one or more primitive surfaces), Processing for obtaining a rotation angle (rotation angle about X, Y or Z axis), processing for moving an object (motion processing), processing for obtaining a viewpoint position (virtual camera position) and a line-of-sight angle (virtual camera rotation angle), Processing to place objects such as map objects in the object space, hit check processing, processing to calculate game results (results, results), processing for multiple players to play in a common game space, game over processing, etc. Can think.
[0046]
Further, the processing unit 100 generates an image that can be seen from a given viewpoint (virtual camera) in the object space, for example, based on the game processing result, and outputs the image to the display unit 190.
[0047]
Further, the processing unit 100 performs various kinds of sound processing based on the above game processing result, generates a sound such as BGM, sound effect, or sound, and outputs the sound to the sound output unit 192.
[0048]
Note that all of the functions of the processing unit 100 may be realized by hardware, or all of them may be realized by a program. Alternatively, it may be realized by both hardware and a program.
[0049]
The processing unit 100 includes a reflection vector calculation unit 110, a reflection vector change unit 112, a shading calculation unit 114, and a drawing unit 130.
[0050]
Here, the reflection vector calculation unit 110, based on the light source information (light source position, light source vector, etc.) and normal information (normal vector, information indicating the direction of the surface, etc.), each component point (vertex, The reflection vector at a primitive point or the like is obtained.
[0051]
The reflection vector changing unit 112 determines the second reflection vector by changing the direction of the reflection vector obtained by the reflection vector calculation unit 110 to the direction of anisotropic reflection (direction specified by the direction of the scratch). . More specifically, the reflection vector is coordinate-converted from a first coordinate system (for example, a world coordinate system) to a second coordinate system that defines the direction of anisotropic reflection. Next, the second reflection vector is obtained by changing the direction of the reflection vector in the second coordinate system. Then, the second reflection vector in the second coordinate system is coordinate-converted back to the first coordinate system.
[0052]
The shading calculation unit 114 performs an object shading calculation based on the second reflection vector obtained by the reflection vector changing unit 112 and viewpoint information (viewpoint position, line-of-sight vector, etc.). The shading calculation in this case may be realized by a Phong model that obtains the intensity (luminance) of the specular reflection light based on the angle formed by the second reflection vector and the line-of-sight vector. You may implement | achieve with the model of Blinn considered to be a collection of minute planes. Alternatively, it may be realized by specular mapping in which texture coordinates are obtained based on the second reflection vector and the specular expression texture is mapped to the object based on the texture coordinates.
[0053]
The drawing unit 130 displays an image of an object (one or more primitive surfaces) after geometry processing (coordinate conversion, clipping processing, perspective conversion, light source calculation, etc.) in a pixel unit such as a drawing area 174 (frame buffer, work buffer, etc.). A drawing process is performed in an area where information can be stored.
[0054]
The drawing data after the geometry processing (position coordinates, texture coordinates, color (luminance) data, normal vector, α value, etc. given to the constituent points) is stored in the main storage unit 172. The drawing unit 130 performs drawing processing based on the drawing data (polygon data).
[0055]
The texture mapping unit 132 included in the drawing unit 130 performs processing for mapping the texture stored in the texture storage unit 176 to the object.
[0056]
For example, when performing specular mapping, texture coordinates are obtained based on the second reflection vector obtained by the reflection vector changing unit 112, and the texture coordinates are assigned to each component point (vertex) of the object. . Then, the texture mapping unit 132 reads the specular expression texture (for example, the texture on which the highlight image to be mapped is drawn) designated by the texture coordinates given to each component point from the texture storage unit 176, and stores it in the object. Map.
[0057]
Note that the game system according to the present embodiment may be a system dedicated to the single player mode in which only one player can play, and not only such a single player mode but also a multiplayer mode in which a plurality of players can play. A system may be provided.
[0058]
Further, when a plurality of players play, game images and game sounds to be provided to the plurality of players may be generated using one terminal, or connected via a network (transmission line, communication line) or the like. Alternatively, it may be generated using a plurality of terminals (game machine, mobile phone).
[0059]
2. Features of this embodiment
2.1 Representation of anisotropic reflection by changing the direction of the reflection vector
The surface of the object having the anisotropic reflection property is considered to be scratched in a specific direction. Due to the presence of this scratch, much of the light incident on the surface of the object is reflected in a direction perpendicular to the direction of the scratch. Therefore, an anisotropic reflection model can be constructed if the direction of the reflection vector on the surface of the object having no scratch can be changed to a direction that takes into consideration the scratch on the surface of the object.
[0060]
Therefore, in this embodiment, first, as shown in FIG. 4A, when the light source vector from the light source LS is L and the normal vector perpendicular to the surface is N, each component point (vertex, The reflection vector R at a primitive point or the like is obtained as in the following equation (2). That is, the reflection vector R is obtained based on the light source information (L) and the normal information (N).
[0061]
R = 2 (N · L) N−L (2)
In FIG. 4A, it is assumed that the scratch on the surface of the object occurs in either the U-axis direction or the V-axis direction.
[0062]
In the present embodiment, the reflection vector R obtained by the above equation (2) is changed in the direction of anisotropic reflection as shown in FIG. 4B, and the reflection vector R2 (second reflection vector) is changed. )
[0063]
More specifically, when it is assumed that the direction of the flaw is the direction of the U axis (one of the first and second axes), as shown in FIG. The reflection vector R2 is obtained by changing (rotating) the direction of R toward the V axis. In this way, the direction of the reflection vector at each constituent point of the object can be uniformly changed toward the V axis perpendicular to the flaw.
[0064]
On the other hand, when the direction of the flaw is assumed to be the direction of the V-axis (the other of the first and second axes), the direction of the reflection vector R is opposite to that in FIG. By changing (rotating) toward the U axis, a reflection vector R2 is obtained. In this way, the direction of the reflection vector at each constituent point of the object can be uniformly changed toward the U axis perpendicular to the flaw.
[0065]
In this embodiment, shading calculation is performed using the reflection vector R2 obtained in this way, and the intensity (luminance) of specular reflection light at each constituent point of the object is obtained.
[0066]
For example, when using a Phong model, if the angle between the reflection vector R2 and the line-of-sight vector is θ, P _S × COS ⁿ θ is calculated and the intensity of the specular reflection light is obtained. P _S Is a specular coefficient (maximum coefficient of specular components), and n is a power coefficient. The extent of highlight can be controlled by changing n.
[0067]
Further, when the Bryn model is used, an intermediate vector between the reflection vector R2 and the light source vector L is obtained, and the intensity of the specular reflection light may be obtained based on the intermediate vector and the line-of-sight vector.
[0068]
By obtaining the intensity of the specular reflection light as described above, in this embodiment, the expression of the anisotropic reflection of the reflection light on the surface of the object is realized with a small processing load. As a result, it is possible to generate images such as a peculiar light / dark pattern (brush effect) that appears on the surface of the knob of the audio device and an “angel ring” (hairline effect) that looks like human hair with a small processing load.
[0069]
More specifically, the process of changing the direction of the reflection vector can be realized by the following method.
[0070]
(I) First, as shown in FIG. 5, based on the calculation of the above equation (2), the reflection vector R (first reflection vector) at each component point (vertex) of the object OB is represented by the world coordinate system (XW, YW). , ZW).
[0071]
(II) Next, as shown by A1 in FIG. 5, the reflection vector R (RX, RY, RZ) is coordinated from the world coordinate system (first coordinate system) to the UVN coordinate system (second coordinate system). The reflection vector RUVN (RU, RN, RV) in the UVN coordinate system is obtained by conversion. This coordinate conversion can be realized, for example, by the following equation (3).
[0072]
[Expression 1]

Here, one of the U axis and the V axis in the UVN coordinate system is an axis representing the direction of the flaw at each component point, and the other axis of the U axis and the V axis is an axis orthogonal to the one axis. It is. In the above equation (3), (UX, UY, UZ) is a unit vector in the U-axis direction, and (VX, VY, VZ) is a unit vector in the V-axis direction. The N axis is an axis set in the direction of the normal vector, and (NX, NY, NZ) in the above equation (3) is a unit vector in the N axis direction.
[0073]
Note that the U-axis and V-axis do not have to be orthogonal to each other, as long as they intersect with each other. Further, the N axis may not be an axis in the direction of the normal vector, and may be an axis that intersects the U axis and the V axis.
[0074]
(III) Next, as shown by A2 in FIG. 5, the direction of the reflection vector RUVN (RU, RN, RV) is changed in the UVN coordinate system to obtain the reflection vector R2UVN (R2U, R2N, R2V). This can be obtained by the following equation (4), for example.
[0075]
[Expression 2]

Here, CU is a scaling coefficient in the U-axis component, and CV is a scaling coefficient in the V-axis direction.
[0076]
(IV) Next, as shown by A3 in FIG. 5, the reflection vector R2UVN (R2U, R2N, R2V) is coordinate-converted from the UVN coordinate system to the world coordinate system, and the reflection vector R2 (R2X in the world coordinate system) is converted. , R2Y, R2Z). This can be obtained by the following equation (5), for example.
[0077]
[Equation 3]

As described above, in this embodiment, the UVN coordinate system that defines the direction of anisotropic reflection is set, and the reflection vector RUVN is changed in this UVN coordinate system to obtain the reflection vector R2UVN. In this way, as shown in the above equation (4), the reflection vector RUVN is reflected by a very simple process in which the U-axis component RU is scaled by the coefficient CU and the V-axis component RV is scaled by the coefficient CV. It becomes possible to obtain the reflection vector R2UVN by changing the vector RUVN in the direction of anisotropic reflection.
[0078]
For example, when the flaw direction is set in the U-axis direction, the scaling coefficient CU in the U-axis direction may be made smaller than 1.0 as shown in FIG. For example, in FIG. 6A, CU = 0.5 and CV = 2.0 are set. By doing so, the reflection vector changes in the direction of the V-axis, which is a direction perpendicular to the scratch, and anisotropic reflection can be expressed.
[0079]
On the other hand, when the flaw direction is set in the V-axis direction, the scaling coefficient CV in the V-axis direction may be made smaller than 1.0 as shown in FIG. For example, in FIG. 6B, CU = 2.0 and CV = 0.5 are set. By doing so, the reflection vector changes in the direction of the U-axis, which is the direction perpendicular to the scratch, and anisotropic reflection can be expressed.
[0080]
Note that the method of changing the direction of the reflection vector by using the scaling coefficient assumes that the direction of the reflection vector does not change beyond the quadrant.
[0081]
6A and 6B, the direction of the reflection vector RUVN is changed using the scaling factors CU and CV. However, the method of changing the direction of the RUVN by rotating the RUVN around the N axis. May be adopted. However, this method has a disadvantage that the processing load becomes heavy because a process of rotating the reflection vector and a process of controlling the direction of the reflection vector so as not to change beyond the quadrant are necessary.
[0082]
On the other hand, in the method of changing the direction of the reflection vector using the scaling factor, it is only necessary to multiply each component of the reflection vector by the scaling factor, and control is performed so that the direction of the reflection vector does not change beyond the quadrant. Is also unnecessary, and there is an advantage that the processing load is very light.
[0083]
FIG. 7A shows an example of a generated image in a case where normal shading processing is performed on the object OB without performing anisotropic reflection processing. When the anisotropic reflection process is not performed, the intensity distribution of the reflected light is isotropic, so that a normal-shaped highlight is generated on the surface of the object OB.
[0084]
FIG. 7B is an example of a generated image when anisotropic reflection is expressed using a conventional ellipsoidal model. In FIG. 7B, it is assumed that there is a concentric scratch on the upper surface of the object OB, and a highlight image expressing the brush effect is generated.
[0085]
On the other hand, FIG. 7C is an example of a generated image when anisotropic reflection is expressed by the method of the present embodiment. In FIG. 7C, the scaling coefficients described in FIGS. 6A and 6B are set to CU = 0.5 and CV = 2.0. Thereby, it is possible to generate a highlight image of the brush effect that is seen when there is a concentric scratch on the upper surface of the object OB.
[0086]
FIG. 8A is an example of a generated image when anisotropic reflection is expressed using a conventional ellipsoidal model. In FIG. 8A, it is assumed that there is a radial scar from the center of the object OB, and a highlight image in which the hairline effect (angel's ring of hair) is expressed is generated.
[0087]
On the other hand, FIG. 8B is an example of a generated image when anisotropic reflection is expressed by the method of the present embodiment. In FIG. 8B, the scaling coefficients are set to CU = 2.0 and CV = 0.5. Thereby, a highlight image of the hairline effect that can be seen when there is a radial scar from the center of the object OB can be generated.
[0088]
FIGS. 9A to 9D and FIGS. 10A to 10D show examples of images of the object OB generated by the present embodiment when the scaling coefficients CU and CV are gradually changed.
[0089]
In FIG. 9A, CU = 0.5 and CV = 2.0 are set. 9 (B), (C), (D), and FIG. 10 (A), (B), (C), (D), CU increases by 0.2 and CV increases by 0.2. is decreasing. In FIG. 9A, a highlight image of the brush effect is generated, and in FIG. 10D, a highlight image of the hairline effect is generated.
[0090]
As described above, according to the present embodiment, it is possible to arbitrarily control the direction of the flaw assumed on the surface of the object simply by changing the values of the scaling factors CU and CV to desired values, such as the brush effect and the hairline effect. It has succeeded in generating various highlight images.
[0091]
2.2 Use of free-form surfaces
Next, a case where an object is represented by a free-form surface will be described. If the object is represented by a free-form surface, the UVN coordinate system described with reference to FIG. 5 can be set by simple processing.
[0092]
P that is the x component of the constituent point Puv (u, v) of the free-form surface ^x uv (u, v) is obtained as in the following equation (6).
[0093]
[Expression 4]

The y component and z component of Puv (u, v) can also be obtained by the same equation as the above equation (6).
[0094]
When rationalization is performed, the following equation (7) is obtained.
[0095]
[Equation 5]

In the above formulas (6) and (7), Q ₀₀ ~ Q ₃₃ Is the control point.
[0096]
Also Nu _0,4 ~ Nu _3,4 , Nv _0,4 ~ Nv _3,4 Is a blending function. These mixing functions can be obtained based on the recursive expression recursive expression (DeBoorCox recursive expression) of the following expressions (8) and (9) and the knot vectors TU and TV of the following expression (10). it can.
[0097]
[Formula 6]

[0098]
[Expression 7]

The knot vector is a vector that gives parameter nodes as a sequence of numerical values. When the knot interval of the knot vector (the numerical difference between adjacent elements of the knot vector) is constant, it is called a uniform (Uniform), and when the knot interval is not constant, it is called a non-uniform (Non Uniform).
[0099]
Non Uniform and Rationalized B-splines are NURBS (Non Uniform Rational B-Spline).
[0100]
FIG. 11 shows an example of the curved surface patch 20 (free curved surface) generated by the present embodiment.
[0101]
As is clear from the above formula (6) or (7), each constituent point of the curved patch 20 is a control point Q. ₀₀ ~ Q ₃₃ And mixing function Nu _0,4 ~ Nu _3,4 , Nv _0,4 ~ Nv _3,4 It is required based on. In this case, the domain of the parameter u is u _Three ≦ u <u _Four And the domain of parameter v is v _Three ≦ v <v _Four become.
[0102]
On the other hand, when generating the curved patch 22, the set of control points to be used is Q ₀₀ ~ Q ₃₃ To Q ₀₁ ~ Q ₃₄ Changes to. Each constituent point of the curved patch 22 is a control point Q. ₀₁ ~ Q ₃₄ And mixing function Nu _1,4 ~ Nu _4,4 , Nv _0,4 ~ Nv _3,4 It is required based on. In this case, the domain of the parameter u is u _Four ≦ u <u _Five And the domain of parameter v is v _Three ≦ v <v _Four become.
[0103]
Each constituent point of the curved surface patch 20 generated according to the present embodiment is set as a vertex of a polygon, and a polygon constituted by these vertices is displayed on the screen.
[0104]
FIG. 12 shows an example of an image of an object OB (wire frame display) represented by a free-form surface (NURBS). By controlling the number of divisions of the curved surface, the precision of the object OB can be changed.
[0105]
When the object is represented by a free-form surface, the tangent (slope) vector of the curved surface can be easily obtained.
[0106]
For example, in FIG. 13, the x component of the tangent vector UVEC in the u direction at the component point P can be obtained by calculating the following equation (11). The same applies to the y component and the z component.
[0107]
[Equation 8]

Further, the x component of the tangent vector VVEC in the v direction can be obtained by calculating the following equation (12). The same applies to the y component and the z component.
[0108]
[Equation 9]

The above equations (12) and (13) are equations when rationalization is not performed, but can be similarly obtained when rationalization is performed.
[0109]
Further, by calculating the outer product of the tangent vectors UVEC and VVEC obtained by the above equations (12) and (13), the normal vector N at the component point P can be obtained as shown in FIG.
[0110]
5 is set in the direction of the tangent vector UVEC, the V axis of the UVN coordinate system is set in the direction of the tangent vector VVEC, and the UVN coordinate system is set in the direction of the normal vector N. Set the N axis.
[0111]
In this way, a UVN coordinate system as shown in FIG. 5 can be set for each constituent point of the object. Then, anisotropic reflection can be expressed by changing the direction of the reflection vector as indicated by A2 in FIG. 5 in the UVN coordinate system set for each component point.
[0112]
Thus, when the object represents a free-form surface, there is an advantage that the UVN coordinate system for changing the reflection vector can be set by a relatively simple process.
[0113]
Further, the tangent vectors UVEC and VVEC obtained for obtaining the normal vector N can be effectively used for the setting process of the UVN coordinate system, and the processing efficiency can be improved.
[0114]
Even when the object is represented by a polygon, the UVN coordinate system can be set by the method described below, for example.
[0115]
For example, in FIG. 14A, in the local coordinate system (XL, YL, ZL) of the object OB (OB1, OB2, or OB3), a circle passing through each component point (vertex) of the object OB with the YL axis as the center is assumed. The U axis is set in the direction of the tangent vector UVEC of this circle. Then, the V-axis direction is obtained by calculating the outer product of this tangent vector UVEC and the normal vector assigned to each component point. In this way, a UVN coordinate system can be set for each constituent point (vertex) of the object OB.
[0116]
Then, according to this method, as shown in FIG. 14B, anisotropic reflection on a metal plate or the like having scratches in a certain direction (the direction of the tangent vector UVEC or the direction perpendicular to UVEC) can be expressed. become.
[0117]
2.3 Specular mapping
Now, it is desirable to realize the shading calculation using the reflection vector R2 obtained in FIG. 4B or the above equation (5) by so-called specular mapping. In Phong's model that calculates the intensity of specular reflection based on the angle formed by the reflection vector R2 and the line-of-sight vector, the specular shape (highlight shape) becomes unnatural due to the influence of the polygon (primitive surface in a broad sense). This is because the problem of becoming may occur.
[0118]
However, in the Ohira, Takagi, and Yokoi models described above, the intensity of specular reflected light, which is a scalar quantity, is output as a calculation result. Therefore, the problem that the specular shape becomes unnatural due to the influence of the polygon shape cannot be solved by a so-called specular mapping method.
[0119]
In this case, the problem that the specular shape depends on the polygon shape can be solved by calculating the intensity of the specular reflection light in units of pixels as in the non-real time processing CG. However, this solution is unrealistic in a game system that requires real-time processing.
[0120]
On the other hand, in the present embodiment, not the scalar quantity but the reflection vector R2 is obtained as in the above equation (5). Therefore, if the texture coordinates are obtained based on the reflection vector R2, and the specular expression texture is mapped to the object based on the texture coordinates, the specular mapping can be realized.
[0121]
More specifically, for example, a specular expression texture as shown in FIG. This specular expression texture may be generated in real time.
[0122]
In the specular expression texture shown in FIG. 15A, for example, a white highlight (light source) image is drawn at the center, and the luminance gradually attenuates from the center toward the periphery and changes to black. Note that it is desirable to change the shape of the highlight image drawn on the specular expression texture so that the highlight image after final polar coordinate conversion described later has a desired appropriate shape.
[0123]
A virtual sphere 30 as shown in FIG. 15B is assumed based on the specular expression texture shown in FIG.
[0124]
Then, as shown in FIG. 16, the virtual sphere 30 is set so as to include the object OB. Next, a reflection vector at the component point P is obtained based on the light source vector L, and a reflection vector R2 in consideration of anisotropic reflection is obtained from the reflection vector by the method of this embodiment. Then, by obtaining the intersection point PR between the reflection vector R2 and the phantom sphere 30, the texture coordinates TX and TY (coordinate values) of the specular expression texture are obtained, and these TX and TY are set as the constituent points P.
[0125]
Then, based on the texture coordinates TX and TY set at each constituent point in this way, the specular expression texture shown in FIG. 15A is mapped to the object OB to realize specular mapping.
[0126]
By doing so, the specular shape (highlight shape) is not affected by the polygon shape, so that a more natural and realistic image can be generated.
[0127]
3. Processing of this embodiment
Next, a detailed example of the processing of this embodiment will be described using the flowcharts of FIGS.
[0128]
First, PN (composition point number) is set to 0 (step S1).
[0129]
Next, tangent vectors UVEC and VVEC at the constituent point (vertex) PN are obtained based on the above formulas (11) and (12) (step S2).
[0130]
Next, as described with reference to FIG. 13, the outer product calculation of the tangent vectors UVEC and VVEC is performed to obtain the normal vector N (step S3).
[0131]
Next, a reflection vector R is obtained based on the light source information, the position of the constituent point PN, and the normal vector N at the constituent point PN (step S4). For example, in the case of a point light source, a vector connecting the light source position and the position of the component point PN is obtained as the light source vector L in FIG. 4A, and the reflection vector R is obtained based on the light source vector L and the normal vector N. . On the other hand, in the case of a parallel light source, a reflection vector R is obtained based on a light source vector L and a normal vector N from the parallel light source.
[0132]
Next, as described in A1 of FIG. 5, the reflection vector R is coordinate-transformed from the world coordinate system to the UVN coordinate system (coordinate system composed of UVEC, VVEC, and N) to obtain RUVN (step S5).
[0133]
Next, as described in A2 of FIG. 5, scaling calculation based on the coefficients CU and CV representing the direction of anisotropic reflection is performed on RUFN in the UVN coordinate system to obtain a reflection vector R2UVN (step S6). .
[0134]
Next, as will be described with reference to A3 in FIG. 5, R2UVN is coordinate-transformed into the world coordinate system to obtain a reflection vector R2 (step S7).
[0135]
Next, based on the angle θ formed by R2 and the line-of-sight vector, for example, P _S × COS ⁿ θ is calculated, and the intensity of the specular reflected light at the constituent point PN is obtained (step S8).
[0136]
Next, it is determined whether or not PN is larger than PEND. If PN is smaller than PEND, PN is incremented by 1 (step S10), and the process returns to step S2. On the other hand, if it is larger than PEND, the process is terminated.
[0137]
FIG. 18 is a flowchart for performing specular mapping. When specular mapping is performed, the process of FIG. 18 is performed in step S8 of FIG.
[0138]
First, when the center of the object is set as the center of the virtual sphere, a matrix M that matches the direction connecting the center of the object and the center of the highlight image on the virtual sphere (the center of the map) with the direction of the line-of-sight vector is set. Obtain (step S11).
[0139]
That is, as shown in FIG. 19A, a virtual sphere 30 whose center coincides with the center of the object OB is assumed. For example, in the case where the line-of-sight vector toward the viewpoint VP in the XYZ coordinate system (which may be set for each constituent point) set for the object is E, it is shown in FIGS. 19B and 19C. Thus, an X′Y′Z ′ coordinate system is assumed in which the direction of the line-of-sight vector E ′ is directed to the negative direction of the X ′ axis. Then, the matrix M is a matrix for converting the line-of-sight vector E ′ to E as shown in the following equation (13).
[0140]
E = M × E '(13)
From the above equation (13),
E '= M ^-1 × E (14)
It becomes. In the above formula (14), M ^-1 Is the inverse transformation matrix of M.
[0141]
And this inverse transformation matrix M ^-1 Based on the above, the reflection vector R2 is converted as shown in the following equation (15) to obtain the reflection vector R2 ′ (step S12).
[0142]
R2 '= M ^-1 × R2 (15)
Next, as shown in FIG. 19D, the reflection vector R2 ′ is subjected to polar coordinate conversion to obtain texture coordinates TX and TY (step S13).
[0143]
That is, as shown in FIG. 19D, a vector obtained by projecting the reflection vector R2 ′ onto the X′Z ′ plane is R2 ″, and the angle between R2 ″ and the X ′ axis is θ1 (degrees). The angle formed by the reflection vector R2 ′ and the Y ′ axis is θ2 (degrees). In this case, the texture coordinates TX and TY can be obtained by the following equation (16).
[0144]
TX = θ1 / 360
TY = θ2 / 180 (16)
For example, in the above equation (16), when θ1 = 180 (degrees) and θ2 = 90 (degrees), as is clear from FIG. 19D, the direction of the reflection vector R2 ′ and the line-of-sight vector E ′ The direction matches. The texture coordinates at this time are TX = 0.5 and TY = 0.5, and the center of the highlight image of the specular expression texture (the center of the map) is referred to. That is, the conversion of the above equation (15) can be said to be a conversion in which the center of the highlight image of the specular expression texture is referred to when the direction of the reflection vector coincides with the direction of the line-of-sight vector.
[0145]
Finally, the obtained texture coordinates TX and TY are assigned to the constituent point PN (vertex) (step S14). By using the texture coordinates TX and TY to map a specular expression texture as shown in FIG. 15A to the object OB, so-called specular mapping can be realized.
[0146]
4). Hardware configuration
Next, an example of a hardware configuration capable of realizing the present embodiment will be described with reference to FIG.
[0147]
The main processor 900 operates based on a program stored in the CD 982 (information storage medium), a program transferred via the communication interface 990, or a program stored in the ROM 950 (one of information storage media). Various processes such as processing, image processing, and sound processing are executed.
[0148]
The coprocessor 902 assists the processing of the main processor 900, has a product-sum calculator and a divider capable of high-speed parallel calculation, and executes matrix calculation (vector calculation) at high speed. For example, if a physical simulation for moving or moving an object requires processing such as matrix operation, a program operating on the main processor 900 instructs (requests) the processing to the coprocessor 902. )
[0149]
The geometry processor 904 performs geometry processing such as coordinate transformation, perspective transformation, light source calculation, and curved surface generation, has a product-sum calculator and a divider capable of high-speed parallel computation, and performs matrix computation (vector computation). Run fast. For example, when processing such as coordinate transformation, perspective transformation, and light source calculation is performed, a program operating on the main processor 900 instructs the geometry processor 904 to perform the processing.
[0150]
The data decompression processor 906 performs a decoding process for decompressing the compressed image data and sound data, and a process for accelerating the decoding process of the main processor 900. As a result, a moving image compressed by the MPEG method or the like can be displayed on the opening screen, the intermission screen, the ending screen, or the game screen. Note that the image data and sound data to be decoded are stored in the ROM 950 and the CD 982 or transferred from the outside via the communication interface 990.
[0151]
The drawing processor 910 performs drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces at high speed. When drawing an object, the main processor 900 uses the function of the DMA controller 970 to pass the object data to the drawing processor 910 and transfer the texture to the texture storage unit 924 if necessary. Then, the rendering processor 910 renders the object in the frame buffer 922 at high speed while performing hidden surface removal using a Z buffer or the like based on the object data and texture. The drawing processor 910 can also perform α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.
[0152]
The sound processor 930 includes a multi-channel ADPCM sound source and the like, and generates high-quality game sounds such as BGM, sound effects, and sounds. The generated game sound is output from the speaker 932.
[0153]
Operation data from the game controller 942, save data from the memory card 944, and personal data are transferred via the serial interface 940.
[0154]
The ROM 950 stores system programs and the like. In the case of an arcade game system, the ROM 950 functions as an information storage medium, and various programs are stored in the ROM 950. A hard disk may be used instead of the ROM 950.
[0155]
The RAM 960 is used as a work area for various processors.
[0156]
The DMA controller 970 controls DMA transfer between the processor and memory (RAM, VRAM, ROM, etc.).
[0157]
The CD drive 980 drives a CD 982 (information storage medium) in which programs, image data, sound data, and the like are stored, and enables access to these programs and data.
[0158]
The communication interface 990 is an interface for transferring data to and from the outside via a network. In this case, as a network connected to the communication interface 990, a communication line (analog telephone line, ISDN), a high-speed serial bus, or the like can be considered. By using a communication line, data transfer via the Internet becomes possible. Further, by using the high-speed serial bus, data transfer with other game systems becomes possible.
[0159]
All of the means of the present invention may be executed by hardware alone, or may be executed only by a program stored in an information storage medium or a program distributed via a communication interface. Alternatively, it may be executed by both hardware and a program.
[0160]
When each means of the present invention is executed by both hardware and a program, a program for executing each means of the present invention using hardware is stored in the information storage medium. Become. More specifically, the program instructs each processor 902, 904, 906, 910, 930, etc., which is hardware, and passes data if necessary. Each processor 902, 904, 906, 910, 930, etc. executes each means of the present invention based on the instruction and the passed data.
[0161]
FIG. 21A shows an example in which the present embodiment is applied to an arcade game system. The player enjoys the game by operating the lever 1102, the button 1104, and the like while viewing the game image displayed on the display 1100. Various processors and various memories are mounted on the built-in system board (circuit board) 1106. Information (program or data) for executing each means of the present invention is stored in a memory 1108 which is an information storage medium on the system board 1106. Hereinafter, this information is referred to as storage information.
[0162]
FIG. 21B shows an example where the present embodiment is applied to a home game system. The player enjoys the game by operating the game controllers 1202 and 1204 while viewing the game image displayed on the display 1200. In this case, the stored information is stored in a CD 1206 or a memory card 1208, 1209, which is an information storage medium that is detachable from the main system.
[0163]
FIG. 21C shows a host device 1300 and terminals 1304-1 to 1304-n connected to the host device 1300 via a network 1302 (a small-scale network such as a LAN or a wide area network such as the Internet). An example in which the present embodiment is applied to a system including (game machine, mobile phone) is shown. In this case, the stored information is stored in an information storage medium 1306 such as a magnetic disk device, a magnetic tape device, or a memory that can be controlled by the host device 1300, for example. When the terminals 1304-1 to 1304-n can generate game images and game sounds stand-alone, the host device 1300 receives a game program and the like for generating game images and game sounds from the terminal 1304-. 1 to 1304-n. On the other hand, if it cannot be generated stand-alone, the host device 1300 generates a game image and a game sound, which is transmitted to the terminals 1304-1 to 1304-n and output at the terminal.
[0164]
In the case of the configuration shown in FIG. 21C, each unit of the present invention may be executed in a distributed manner between the host device (server) and the terminal. The storage information for executing each means of the present invention may be distributed and stored in the information storage medium of the host device (server) and the information storage medium of the terminal.
[0165]
The terminal connected to the network may be a home game system or an arcade game system. When the arcade game system is connected to a network, the save information storage device can exchange information with the arcade game system and exchange information with the home game system. It is desirable to use (memory card, portable game device).
[0166]
The present invention is not limited to the one described in the above embodiment, and various modifications can be made.
[0167]
For example, in the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention can be made dependent on another independent claim.
[0168]
Further, as a method of changing the direction of the reflection vector, the method described with reference to FIG. 5 is particularly desirable from the viewpoint of simplification of processing, but the present invention is not limited to this, and various modifications can be made.
[0169]
Further, the second coordinate system setting method is not limited to the method described with reference to FIGS. 13, 14 </ b> A, and 14 </ b> B.
[0170]
Further, the intensity (luminance) of the specular reflection light obtained by the shading calculation is set to an α value (information stored in association with each pixel, plus alpha information other than color information), and based on this α value. Then, α composition (α blending, α addition) may be performed to express a state in which reflected light is anisotropically reflected by a scratch on the glass surface, for example.
[0171]
The present invention can also be applied to various games (such as fighting games, shooting games, robot battle games, sports games, competitive games, role playing games, music playing games, dance games, etc.).
[0172]
The present invention is also applicable to various game systems (image generation systems) such as a commercial game system, a home game system, a large attraction system in which a large number of players participate, a simulator, a multimedia terminal, and a system board for generating game images. Applicable.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams for explaining anisotropic reflection. FIGS.
FIGS. 2A and 2B are diagrams for explaining a method for realizing anisotropic reflection using an ellipsoid model. FIGS.
FIG. 3 is an example of a functional block diagram of the game system of the present embodiment.
FIGS. 4A and 4B are diagrams for explaining a method for realizing anisotropic reflection by changing the direction of a reflection vector. FIGS.
FIG. 5 is a diagram for explaining a technique for realizing anisotropic reflection by changing the direction of a reflection vector in a UVN coordinate system.
FIGS. 6A and 6B are diagrams for describing a method of changing the direction of a reflection vector using a scaling coefficient.
7A is an example of a generated image in the case of normal shading, FIG. 7B is an example of a generated image when an ellipsoidal model is used, and FIG. 7C is an example of a generated image when the method of this embodiment is used. .
8A is an example of a generated image when an ellipsoid model is used, and FIG. 8B is an example of a generated image when the method of this embodiment is used.
FIGS. 9A, 9B, 9C, and 9D are examples of generated images when the scaling coefficient is gradually changed.
10 (A), (B), (C), and (D) are also examples of generated images when the scaling coefficient is gradually changed. FIG.
FIG. 11 is a diagram for explaining a method of expressing an object by a free-form surface.
FIG. 12 is a diagram for explaining a method of expressing an object by a free-form surface.
FIG. 13 is a diagram for explaining a method of obtaining a tangent vector at each constituent point and setting a UVN coordinate system.
FIGS. 14A and 14B are diagrams for explaining a UVN coordinate system setting method when an object is represented by a polygon.
FIGS. 15A and 15B are diagrams for explaining a specular expression texture and a virtual sphere. FIG.
FIG. 16 is a diagram for describing specular mapping;
FIG. 17 is a flowchart illustrating a detailed example of processing according to the embodiment.
FIG. 18 is a flowchart illustrating a detailed example of processing according to the embodiment.
FIGS. 19A, 19B, 19C, and 19D are diagrams for explaining how to obtain texture coordinates of a specular expression texture.
FIG. 20 is a diagram illustrating an example of a hardware configuration capable of realizing the present embodiment.
FIGS. 21A, 21B, and 21C are diagrams illustrating examples of various types of systems to which the present embodiment is applied.
[Explanation of symbols]
OB object
LS light source
VP perspective
L light source vector
N normal vector
R, R2, RUVN, R2UVN reflection vector
20, 22 Curved patch
30 virtual spheres
100 processor
110 Reflection vector calculation unit
112 Reflection vector changing part
114 Shading calculation unit
130 Drawing part
132 Texture mapping section
160 Operation unit
170 Storage unit
172 Main memory
174 Drawing area
176 texture storage
180 Information storage medium
190 Display
192 sound output section
194 Portable information storage device
196 Communication Department

Claims (16)

A game system for generating images,
Means for obtaining a reflection vector at each constituent point of the object based on the light source information and the normal information;
Reflection vector changing means for obtaining a second reflection vector by changing the direction of the reflection vector to a direction based on a flaw direction vector set at each of the constituent points ;
Shading calculation means for performing a shading calculation of an object based on the second reflection vector and viewpoint information ,
The game system according to claim 1, wherein the flaw direction vector is set according to the flaw direction when it is assumed that the object surface has a flaw in a specific direction . In claim 1,
The reflection vector changing means is
Coordinate-transforming the reflection vector into a second coordinate system that defines a direction based on the flaw direction vector, and changing the direction of the reflection vector in the second coordinate system to obtain the second reflection vector; Coordinate-transforming the second reflection vector in the second coordinate system into the first coordinate system;
The shading calculation means is
A game system, wherein an object shading operation is performed based on the second reflection vector in the first coordinate system. In claim 2,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis,
The reflection vector changing means is
A game system characterized in that the second reflection vector is obtained by changing the direction of the reflection vector in the second coordinate system to one of the first and second axes. In claim 2 or 3,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis,
The reflection vector changing means is
The component of the first axis of the reflection vector in the second coordinate system is scaled by a first coefficient, and the component of the second axis of the reflection vector in the second coordinate system is scaled. A game system characterized in that the second reflection vector is obtained by scaling by a factor of two. In any of claims 2 to 4,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis, and the object is represented by a free-form surface,
A game system, wherein the first and second axes are set in the directions of two tangent vectors at respective constituent points of a free-form surface. In claim 5,
A game system characterized in that a normal vector serving as the normal information is obtained based on the two tangent vectors, and a third axis of the second coordinate system is set in the direction of the normal vector. . In any one of Claims 1 thru | or 6.
The shading calculation means is
A game system, wherein texture coordinates of a specular expression texture are obtained based on the second reflection vector, and the specular expression texture is mapped to an object based on the obtained texture coordinates. In claim 7,
The shading calculation means is
When the direction of the second reflection vector coincides with the direction of the line-of-sight vector, a conversion is performed on the second reflection vector by referring to the center of the highlight image drawn on the specular expression texture. A game system, wherein the texture coordinates are obtained based on the second reflection vector. A computer-readable information storage medium,
Means for obtaining a reflection vector at each constituent point of the object based on the light source information and the normal information;
Reflection vector changing means for obtaining a second reflection vector by changing the direction of the reflection vector to a direction based on a flaw direction vector set at each of the constituent points ;
Storing a program for causing a computer to function as a shading calculation means for performing a shading calculation of an object based on the second reflection vector and viewpoint information ;
The information storage medium according to claim 1, wherein the flaw direction vector is set according to the flaw direction when it is assumed that the object surface has a flaw in a specific direction . In claim 9,
The reflection vector changing means is
Coordinate-transforming the reflection vector into a second coordinate system that defines a direction based on the flaw direction vector, and changing the direction of the reflection vector in the second coordinate system to obtain the second reflection vector; Coordinate-transforming the second reflection vector in the second coordinate system into the first coordinate system;
The shading calculation means is
An information storage medium that performs shading calculation of an object based on the second reflection vector in the first coordinate system. In claim 10,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis,
The reflection vector changing means is
An information storage medium characterized in that the second reflection vector is obtained by changing the direction of the reflection vector in the second coordinate system to one of the first and second axes. In claim 10 or 11,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis,
The reflection vector changing means is
The component of the first axis of the reflection vector in the second coordinate system is scaled by a first coefficient, and the component of the second axis of the reflection vector in the second coordinate system is scaled. An information storage medium characterized in that the second reflection vector is obtained by scaling by a coefficient of 2. In any of claims 10 to 12,
When the second coordinate system has a first axis representing a direction based on the flaw direction vector and a second axis intersecting the first axis, and the object is represented by a free-form surface,
An information storage medium characterized in that the first and second axes are set in the directions of two tangent vectors at each constituent point of a free-form surface. In claim 13,
A normal vector serving as the normal vector is obtained based on the two tangent vectors, and a third axis of the second coordinate system is set in the direction of the normal vector. Medium. In any of claims 9 to 14,
The shading calculation means is
An information storage medium, wherein texture coordinates of a specular expression texture are obtained based on the second reflection vector, and the specular expression texture is mapped to an object based on the obtained texture coordinates. In claim 15,
The shading calculation means is
When the direction of the second reflection vector coincides with the direction of the line-of-sight vector, a conversion is performed on the second reflection vector by referring to the center of the highlight image drawn on the specular expression texture. An information storage medium characterized in that the texture coordinates are obtained based on the second reflection vector.

Images