JP5900254B2 - Line drawing apparatus, line drawing method, and line drawing program - Google Patents

Description

  The disclosed technology relates to a line drawing apparatus, a line drawing method, and a line drawing program.

  Conventionally, line drawing is one of drawing methods in the field of computer graphics and the like. There are two drawing methods for line drawing: “independent lines” and “continuous lines”.

  In independent line drawing, since each line is independent, even if the end point of a line overlaps the start point of the next line to be drawn, each point (pixel) is drawn as it is. That is, in the case of an independent line, “twisting” in which a contact point between lines is drawn twice is allowed.

  For example, when the coordinates of points A to F are specified as shown in FIG. 20 and it is instructed to draw four lines L101 to L104 as independent lines, the start point of the line L101 is the point A and the end point is the point B A line is drawn from point A to point B. The start point of the line L102 is point B and the end point is point C, and a line is drawn from point B to point C. The point B, which is the starting point of the line L102, is also the end point of the line L101, but since it is an independent line, the point B is hit twice. The start point of the line L103 is the C point and the end point is the D point, and the line is drawn from the C point to the D point. Since the point C, which is the starting point of the line L103, is also the end point of the line L102, the point C is hit twice in the same manner as the point B. The starting point of the line L104 is the point E and the end point is the point F, and the line is drawn from the point E to the point F.

  Therefore, the number of coordinates for drawing an independent line is “the number of lines to be drawn × 2”.

  On the other hand, in drawing a continuous line, it is necessary to connect the contact points between the lines without any gaps, and it is not allowed to strike the contact points between the lines twice.

  Therefore, in the example of FIG. 20, the three lines L101 to L103 from the point A to the point D are treated as one line by drawing at a time. For this reason, in the continuous line drawing, the coordinates of the start point and end point are required for the first line, but the start point of the next line is the end point of the previous line. Only the coordinates of are required. In the example of FIG. 20, the first line L101 has a start point A and an end point B. Since the start point of the next line L102 is the same as the B point that is the end point of the previous line L101, it is not necessary to specify the start point, and only the C point that is the end point needs to be specified. Similarly, since the start point of the next line L103 is the same as the point C that is the end point of the previous line L102, it is not necessary to specify the start point, and only the D point that is the end point needs to be specified.

  Accordingly, the number of coordinates for drawing continuous lines is “the number of lines forming a line drawn at one time + 1”.

  As a technique for preventing double strike at the contact point between lines in continuous line drawing, it is determined whether or not the coordinates of the start point of the second line coincide with the coordinates of the end point of the first line. For example, there is a technique for changing the coordinates of the starting point.

  However, with this technique, if it is determined that a double strike will occur, the coordinates of the starting point will be unconditionally changed, so the coordinates may be unnecessarily corrected, and at a position where drawing is not originally required. It may be drawn.

  One of the line drawing algorithms is a drawing method called DiamondExitRule (hereinafter sometimes referred to as DER). Hereinafter, DiamondExitRule will be described.

  FIG. 21 shows an example of a Diamond frame set in a pixel. As shown in the figure, the diamond frame Dm is a diamond-shaped frame formed by connecting the middle points of the sides of the square pixel PXL.

  In DiamondExitRule, first, it is determined whether the coordinates of the input vertex (the start point or end point of the line) are within or outside the frame of the Diamond frame Dm. Specifically, first, the coordinates of the center position of the pixel PXL is P0 (X0, Y0), the coordinates of the input vertex are P1 (X1, Y1), and the vertex represented by the coordinate P1 is within the frame of the Diamond frame Dm. The D value for determining whether the frame is out of the frame is calculated by the following equation. The coordinate value is represented by a real value including a decimal point, the integer part indicates the position of the pixel, and the decimal part indicates the position in the pixel.

D = | X1-X0 | + | Y1-Y0 | (1)

  The point on the Diamond frame Dm is a point where the D value calculated by the above equation (1) is “0.5”. Therefore, when D <0.5 is satisfied, the input vertex is within the frame of the Diamond frame Dm, and when D ≧ 0.5, it is determined that the input vertex is outside the frame of the Diamond frame Dm. .

  In DiamondExitRule, a pixel in which a line connecting the start point and the end point intersects the Diamond frame Dm at least once in the pixel is drawn. Specifically, a pixel through which a line from the inside of the Diamond frame Dm to the outside of the frame passes is drawn.

  FIG. 22 shows an application example of DiamondExitRule. In the figure, the colored pixels are pixels drawn based on DiamondExitRule. As shown in the figure, the starting point S15 of the line L15 is outside the diamond frame Dm. Since the line passing over the pixel including the start point S15 does not include the line going from the inside of the diamond frame Dm to the outside of the frame, the pixel including the start point S15 is not drawn. The end point E15 of the line L15 is outside the diamond frame Dm. Since the line passing over the pixel including the end point E15 does not include the line going from the inside of the diamond frame Dm to the outside of the frame, the pixel including the end point E15 is not drawn.

  The starting point S16 of the line L16 is within the diamond frame Dm. Since the line passing over the pixel including the start point S16 includes a line from the inside of the diamond frame Dm to the outside of the frame, the pixel including the start point S16 is drawn. Further, the end point E16 of the line L16 is within the frame of the Diamond frame Dm. Since the line passing over the pixel including the end point E16 does not include the line going from the inside of the diamond frame Dm to the outside of the frame, the pixel including the end point E16 is not drawn.

  The starting point S17 of the line L17 is outside the diamond frame Dm. Since the line passing over the pixel including the start point S17 includes a line going from the inside of the diamond frame Dm to the outside of the frame, the pixel including the start point S17 is drawn. In addition, the end point of the line L17 is outside the diamond frame Dm. Since the line passing over the pixel including the end point E17 includes a line from the inside of the Diamond frame Dm to the outside of the frame, the pixel including the end point E17 is drawn.

  FIG. 23 shows an example in which the DiamondExitRule is applied and two lines L18 and L19 are continuously drawn. As shown in the figure, according to DiamondExitRule, the start point S18 of the first line L18 is drawn because it includes a line going from the inside of the Diamond frame Dm to the outside of the frame, and the end point E18 is drawn from the inside of the Diamond frame Dm to the outside of the frame. It is not drawn because it does not include the line to go. The end point E18 of the first line is also the start point S19 of the second line. According to DiamondExitRule, the start point S19 of the second line is drawn because it includes a line that goes from the inside of the Diamond frame Dm to the outside of the frame, and the end point E19 is drawn because it includes a line that goes from the inside of the Diamond frame Dm to the outside of the frame.

JP-A 63-245575 JP 2010-9350 A

  On the other hand, in the example shown in FIG. 24, for example, according to DiamondExitRule, the end point E20 of the line L20 of the first line is drawn because it includes a line from the inside of the Diamond frame Dm to the outside of the frame. The start point S21 of the second line L21 is also the end point E20 of the first line L20, and is drawn because it includes a line from the inside of the Diamond frame Dm to the outside of the frame. That is, the pixel including the end point E20 of the first line (start point S21 of the second line) is drawn twice (twice).

  As described above, when a continuous line is drawn according to the DER algorithm, a pixel at a contact point between the lines may be hit twice.

  Here, a case will be considered in which a continuous line is drawn by applying a technique for changing the coordinates of the start point to the DER when the coordinates of the start point of the second line coincide with the coordinates of the end point of the first line. In this case, it is necessary to temporarily draw the second line by DER and detect whether or not a double strike occurs, and when it is detected that the double strike occurs, the start point of the second line needs to be changed. Yes, the processing load increases.

  The technique of the disclosure is intended to prevent double hitting of contact points between lines with a small processing load when drawing continuous lines.

In the disclosed technology, the drawing information generation unit receives the coordinate information of the first and second lines, generates the drawing information of the first line based on the drawing rule, and sets the end point of the first line to the next First drawing information for continuous drawing is generated as the starting point of the second line to be drawn. The end point drawing determination unit determines whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line. To do. The start point correction determination unit, when the drawing determination unit determines to draw the pixel including the end point of the first line, the coordinates of the start point of the second line that is the end point of the first line and the second line The drawing direction of the second line is determined based on the coordinates of the end point. In addition, the start point correction determination unit determines whether correction of the start point coordinates of the second line is necessary based on the start point coordinates of the second line and the drawing direction of the second line. When it is determined that the correction of the coordinates of the start point of the second line is necessary, the coordinate correction processing unit corrects the coordinates of the start point of the second line to the coordinates in the pixel adjacent to the pixel including the start point.
When the length of the second line in the principal axis direction is 1 pixel or more, the line disappearance determination unit outputs the coordinates of the start point of the second line corrected by the coordinate correction processing unit as second drawing information. . In addition, when the length of the second line in the principal axis direction is less than 1 pixel, the line disappearance determination unit determines that the second line should be disappeared and does not draw the second line. The drawing processing unit performs drawing processing based on the first drawing information or the second drawing information.

  The disclosed technology has an effect that, when a continuous line is drawn, it is possible to prevent double contact of the contact points between the lines with a small processing load.

It is a functional block diagram of a drawing apparatus. It is a functional block diagram of the graphic chip to which a drawing apparatus is applied. It is a functional block diagram of a line setup part. It is a schematic block diagram of the computer which functions as a line setup part. It is a flowchart which shows the flow of a process of a line drawing program. It is a figure for demonstrating spindle determination. It is a flowchart which shows the flow of an end point drawing determination process. It is a flowchart which shows the flow of a starting point correction | amendment determination process and a coordinate correction process. It is a figure for demonstrating an example of starting point correction | amendment. It is a flowchart which shows the flow of a line disappearance determination process. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating an example of a line loss | disappearance. It is a figure for demonstrating the case where a continuous line is drawn. It is a figure for demonstrating an independent line and a continuous line. It is a figure for demonstrating a Diamond frame. It is a figure for demonstrating the case where a line is drawn by DiamondExitRule. It is a figure for demonstrating the case where a double strike does not generate | occur | produce when drawing a continuous line by DiamondExitRule. It is a figure for demonstrating the case where a double strike occurs when drawing a continuous line by DiamondExitRule.

  Hereinafter, an example of an embodiment of the disclosed technology will be described in detail with reference to the drawings. In the present embodiment, a case where a continuous line is drawn by applying the above-described DiamondExitRule will be described.

  FIG. 1 shows a block diagram of a drawing apparatus 10 according to the present embodiment. As illustrated in FIG. 1, the drawing apparatus 10 includes a vertex processing unit 12, a graphic setup unit 14, and a drawing processing unit 16.

  The vertex processing unit 12 inputs vertex data (X coordinate, Y coordinate, Z coordinate, RGB value, etc.), and forms a figure in the figure setup unit 14 according to the figure to be formed (triangle, straight line, etc.). Send vertex coordinate data. In the present embodiment, a case will be described in which the coordinate data is represented by an X coordinate and a Y coordinate.

  The graphic setup unit 14 includes a triangle setup unit 18, a line setup unit 20, and a selection unit 22. The graphic setup unit 14 executes setup processing in the triangle setup unit 18 for triangle (triangle) drawing, and executes setup processing in the line setup unit 20 for line (straight line) drawing. For example, in the case of line drawing, the set-up process uses drawing data (such as vertex coordinates, line inclination value, line length, spindle information, etc.) necessary for drawing a line as coordinate data. Based on this, it outputs to the selector 22. In the case of triangle drawing, drawing information necessary for drawing a triangle is calculated based on the vertex data and output to the selection unit 22.

  The selection unit 22 selects any of the drawing information output from the triangle setup unit 18 and the line setup unit 20 and outputs the selected drawing information to the drawing processing unit 16.

  The drawing processing unit 16 executes drawing processing based on the drawing information output from the graphic setup unit 14. Specifically, for example, an RGB value as display data is stored in an address corresponding to each coordinate in a frame buffer (external memory) which is a buffer for a screen image.

  The drawing apparatus 10 is mounted on, for example, a graphic chip such as a car navigation system. FIG. 2 shows the configuration of such a graphic chip 30. As shown in the figure, the graphic chip 30 includes a drawing device 10, a memory controller 32, a capture controller 34, and a display controller 36 connected by a bus 38. The drawing apparatus 10 is connected to an external interface via the host interface 40 and the bus 42.

  The drawing apparatus 10 performs drawing according to the program content of the programmable shader 44. At this time, vertex data is acquired from the memory controller 32 and the capture controller 34 connected via the bus 38, the above processing is executed to generate drawing information, and output to the display controller 36. The display controller 36 includes a frame buffer for storing the drawing information output from the drawing device 10 and displays an image on the display based on the drawing information stored in the frame buffer.

  FIG. 3 shows the configuration of the line setup unit 20. As shown in the figure, the line setup unit 20 includes a Diamond ExitRule processing unit (hereinafter referred to as DER processing unit) 50, a line drawing determination unit 52, and a selection unit 54.

  The DER processing unit 50 generates drawing information for drawing a line connecting the input start point and end point based on the above-described DiamondExitRule, and outputs the drawing information to the selection unit 54. The DER processing unit 50 is an example of a drawing information generation unit in the disclosed technology.

  The line drawing determination unit 52 includes a drawing direction determination unit 56, a main axis determination unit 58, an end point drawing determination unit 60, a start point correction determination unit 62, a coordinate correction processing unit 64, and a line disappearance determination unit 66.

  The drawing direction determination unit 56 determines the drawing direction of the line based on the X and Y coordinates of the start point and end point of the line.

  Based on the coordinates of the start point and the end point, the main axis determination unit 58 determines whether the main axis (details will be described later) of the line connecting the start point and the end point is the X axis or the Y main axis.

  The end point drawing determination unit 60 determines whether to draw a pixel including the end point of the previous line, based on the coordinates in the pixel area of the end point of the previous line (first line) and the drawing direction of the previous line. .

  When it is determined that the end point of the previous line is to be drawn, the start point correction determination unit 62 determines the next line based on the coordinates of the start point of the next line (second line) that is the end point of the previous line and the coordinates of the end point of the next line. The drawing direction is determined. The start point correction determination unit 62 determines whether or not the start point of the next line needs to be corrected based on the coordinates in the pixel area of the start point of the next line and the drawing direction of the next line.

  When it is determined that the start point of the next line needs to be corrected, the coordinate correction processing unit 64 corrects the coordinates of the start point of the next line to the coordinates in the pixel adjacent to the pixel including the start point.

  The line disappearance determination unit 66 outputs the coordinates of the start point of the next line corrected by the coordinate correction processing unit 64 to the DER processing unit 50 when the length of the next line in the principal axis direction is 1 pixel or more. Further, the line disappearance determination unit 66 determines that the next line should be lost when the length of the next line in the principal axis direction is less than 1 pixel, and causes the DER processing unit 50 not to draw the next line. Notice.

  The selection unit 54 selects and outputs any of the drawing information output from the DER processing unit 50 and the line drawing determination unit 52.

  The line setup unit 20 can be realized, for example, by a computer 70 shown in FIG. The computer 70 includes a CPU 72, a memory 74, and a nonvolatile storage unit 76, which are connected to each other via a bus 78.

  The storage unit 76 can be realized by an HDD (Hard Disk Drive), a flash memory, or the like. A storage unit 76 as a recording medium stores a line drawing program 80 for causing the computer 70 to function as the line setup unit 20. The CPU 72 reads the line drawing program 80 from the storage unit 76 and expands it in the memory 74, and sequentially executes the processes of the line drawing program 80.

  The line drawing program 80 includes a drawing direction determination process 82, a main axis determination process 84, an end point drawing determination process 86, a start point correction determination process 88, a coordinate correction processing process 90, a line disappearance determination process 92, and a DER processing process 94. The CPU 72 operates as the drawing direction determination unit 56 shown in FIG. 3 by executing the drawing direction determination process 82. Further, the CPU 72 operates as the spindle determining unit 58 shown in FIG. 3 by executing the spindle determining process 84. Further, the CPU 72 operates as the end point drawing determination unit 60 shown in FIG. 3 by executing the end point drawing determination process 86. Further, the CPU 72 operates as the start point correction determination unit 62 illustrated in FIG. 3 by executing the start point correction determination process 88. The CPU 72 operates as the coordinate correction processing unit 64 shown in FIG. 3 by executing the coordinate correction processing process 90. Further, the CPU 72 operates as the line disappearance determination unit 66 illustrated in FIG. 3 by executing the line disappearance determination process 92. Further, the CPU 72 operates as the DER processing unit 50 illustrated in FIG. 3 by executing the DER processing process 94.

  As a result, the computer 70 that has executed the line drawing program 80 functions as the line setup unit 20. The line drawing program 80 is an example of a line drawing program in the disclosed technology. The line setup unit 20 is an example of a line drawing apparatus in the disclosed technology.

  The line setup unit 20 can also be realized by, for example, a semiconductor integrated circuit, more specifically, an ASIC (Application Specific Integrated Circuit).

  Next, the operation of this embodiment will be described. When the coordinate data of the start point and end point of the line to be drawn is input from the vertex processing unit 12, the line setup unit 20 executes the line drawing process shown in FIG.

  In step 100, the vertex processing unit 12 inputs the coordinate data of the start point and end point of the line to be drawn.

  In step 102, the main axis determination unit 58 determines whether the main axis of the line connecting the start point and the end point is the X axis or the Y axis based on the coordinates of the start point and the end point. Specifically, ΔX ≧ ΔY is satisfied, where ΔX is the absolute value of the value obtained by subtracting the X coordinate of the start point from the X coordinate of the end point, and ΔY is the absolute value of the value obtained by subtracting the Y coordinate of the start point from the Y coordinate of the end point. Determines that the X axis is the principal axis, and if ΔX <ΔY is satisfied, determines that the Y axis is the principal axis.

  For example, in the case of the line LA shown in FIG. 6A, since ΔX ≧ ΔY is satisfied, the X axis is determined as the main axis, and in the case of the line LB shown in FIG. 6B, ΔX <ΔY is satisfied, so the Y axis is the main axis. It is determined that there is.

  When the X axis is the main axis, the X coordinate is defined as the main axis coordinate and the Y coordinate is defined as the sub axis coordinate. When the Y axis is the main axis, the Y coordinate is defined as the main axis coordinate and the X coordinate is defined as the sub axis coordinate.

  In step 104, the drawing direction determination unit 56 determines the line drawing direction based on the X and Y coordinates of the start point and end point. Specifically, when the X axis is the main axis, if the value obtained by subtracting the X coordinate of the start point from the X coordinate of the end point is a positive value, the drawing direction is determined to be the positive direction of the X direction, and the end point X If the negative value is obtained by subtracting the X coordinate of the starting point from the coordinates, it is determined that the drawing direction is the negative direction of the X direction. In the present embodiment, for the X direction, the right direction in FIG. 6 is the positive direction and the left direction is the negative direction, and for the Y direction, the downward direction is the positive direction and the upward direction is the negative direction in FIG.

  In step 106, the end point drawing determination unit 60 determines whether to draw a pixel including the end point of the previous line based on the coordinates in the pixel area of the end point of the previous line and the drawing direction of the previous line. Specifically, the end point drawing determination unit 60 executes the end point drawing determination process shown in FIG.

  In step 200 in FIG. 7, the end point drawing determination unit 60 determines whether the main axis of the previous line is the X axis or the Y axis. If the X axis is the main axis, the process proceeds to step 202, where the Y axis If is the main axis, the routine proceeds to step 212.

  When the X axis is the principal axis, in step 202, the end point drawing determination unit 60 determines whether the coordinates of the end point of the previous line are outside the frame of the Diamond frame Dm. As shown in FIG. 21, areas outside the frame exist at the upper left, lower left, upper right, and lower right of the Diamond frame Dm set in the pixel. If the coordinates of the end point of the previous line are within the frame of the Diamond frame Dm, the process proceeds to step 206, and it is determined that the pixel including the end point of the previous line is not drawn. On the other hand, if the coordinates of the end point of the previous line are outside the upper left or lower left frame of the Diamond frame Dm, the process proceeds to step 204, and the coordinates of the end point of the previous line is outside the upper right or lower right frame of the Diamond frame Dm. In step S208, the process proceeds to step 208.

  When the coordinates of the end point of the previous line are outside the upper left or lower left frame of the Diamond frame Dm, in step 204, the end point drawing determination unit 60 determines whether the drawing direction of the previous line is positive or negative. If the drawing direction of the previous line is positive, it is determined in step 206 that pixels including the end point of the previous line are not drawn. If the drawing direction of the previous line is negative, the previous line is checked in step 210. It is determined that a pixel including the end point of is drawn.

  If the coordinates of the end point of the previous line are outside the upper right or lower right frame of the Diamond frame Dm, in step 208, the end point drawing determination unit 60 determines whether the drawing direction of the previous line is positive or negative. . If the drawing direction of the previous line is positive, it is determined in step 210 that pixels including the end point of the previous line are drawn. If the drawing direction of the previous line is negative, the previous line is determined in step 206. It is determined that the pixel including the end point is not drawn.

  That is, when the X axis is the main axis and the coordinates of the end point of the previous line are outside the upper left or lower left frame of the Diamond frame Dm and the drawing direction is negative, the line passing over the pixel including the end point of the previous line is Since the line goes from the inside of the frame to the outside of the frame, it is determined that the pixel is drawn. Similarly, when the X axis is the main axis and the coordinates of the end point of the previous line are outside the upper right or lower right frame of the Diamond frame Dm and the drawing direction is positive, the line passing over the pixel including the end point of the previous line is the Diamond frame. Since the line goes from the inside of Dm to the outside of the frame, it is determined that the pixel is drawn.

  On the other hand, when the Y axis is the principal axis, in step 212, the end point drawing determination unit 60 determines whether or not the coordinates of the end point of the previous line are outside the frame of the Diamond frame Dm. If the coordinates of the end point of the previous line are within the frame of the Diamond frame Dm, the process proceeds to step 216, and it is determined that the pixel including the end point of the previous line is not drawn. On the other hand, if the coordinates of the end point of the previous line are outside the upper left or upper right frame of the Diamond frame Dm, the process proceeds to step 214, and the coordinates of the end point of the previous line is outside the lower left or lower right frame of the Diamond frame Dm. In step S218, the process proceeds to step 218.

  If the coordinates of the end point of the previous line are outside the upper left or upper right frame of the Diamond frame Dm, in step 214, the end point drawing determination unit 60 determines whether the drawing direction of the previous line is positive or negative. If the drawing direction of the previous line is positive, it is determined in step 216 that pixels including the end point of the previous line are not drawn. If the drawing direction of the previous line is negative, the previous line is determined in step 220. It is determined that a pixel including the end point of is drawn.

  If the coordinates of the end point of the previous line are outside the lower left or lower right frame of the Diamond frame Dm, in step 218, the end point drawing determination unit 60 determines whether the drawing direction of the previous line is positive or negative. . If the drawing direction of the previous line is positive, it is determined in step 220 that pixels including the end point of the previous line are drawn. If the drawing direction of the previous line is negative, the previous line is drawn in step 216. It is determined that the pixel including the end point is not drawn.

  That is, when the Y axis is the main axis and the coordinates of the end point of the previous line are outside the upper left or upper right frame of the Diamond frame Dm and the drawing direction is negative, the line passing over the pixel including the end point of the previous line is Since the line goes from the inside of the frame to the outside of the frame, it is determined that the pixel is drawn. Similarly, when the X axis is the main axis and the coordinates of the end point of the previous line are outside the lower left or lower right frame of the Diamond frame Dm and the drawing direction is positive, the line passing over the pixel including the end point of the previous line is the Diamond frame. Since the line goes from the inside of Dm to the outside of the frame, it is determined that the pixel is drawn.

  In step 108 of FIG. 5, the end point drawing determination unit 60 determines whether it is determined to draw a pixel including the end point of the previous line. If it is determined that there is drawing, the process proceeds to step 110, and no drawing is performed. If so, the process proceeds to step 116.

  In step 110, when it is determined that the start point correction determination unit 62 draws the end point of the previous line, the start point of the next line is determined based on the start point coordinates of the next line and the end point coordinates of the next line. Determine the drawing direction. The start point correction determination unit 62 determines whether or not the start point of the next line needs to be corrected based on the coordinates in the pixel area of the start point of the next line and the drawing direction of the next line. Specifically, the start point correction determination unit 62 executes a start point correction determination process shown in FIG.

  In step 300 of FIG. 8, the start point correction determination unit 62 determines whether the main axis of the next line is the X axis or the Y axis. If the X axis is the main axis, the process proceeds to step 302, where the Y axis If is the main axis, the process proceeds to step 308.

  When the X axis is the principal axis, in step 302, the start point correction determination unit 62 determines at which position of the diamond frame Dm the coordinates of the start point of the next line (the coordinates of the end point of the previous line) are outside the frame. If the coordinates of the start point of the next line is outside the upper left or lower left frame, the process proceeds to step 304 to determine whether the drawing direction of the next line is positive. Here, when the coordinates of the start point of the next line are out of the upper left or lower left frame and the drawing direction of the next line is positive, a pixel including the start point of the next line is drawn, that is, hit twice. Therefore, the determination in step 304 can be said to be a process of determining whether or not to strike twice, that is, whether or not the start point needs to be corrected. If the drawing direction of the next line is positive and the start point of the next line needs to be corrected, the process proceeds to step 400, where the drawing direction of the next line is negative and the start point of the next line need not be corrected. If so, the process proceeds to step 116 in FIG.

  If the coordinates of the start point of the next line is outside the upper right or lower right frame, the process proceeds to step 306 to determine whether the drawing direction of the next line is negative. Here, when the coordinates of the start point of the next line are out of the upper right or lower right frame and the drawing direction of the next line is negative, the pixel including the start point of the next line is drawn, that is, hit twice. Therefore, the determination in step 306 can be said to be a process of determining whether or not to strike twice, that is, whether or not the start point needs to be corrected. If the drawing direction of the next line is negative and the start point of the next line needs to be corrected, the process proceeds to step 402, and the drawing direction of the next line is negative and there is no need to correct the start point of the next line. If so, the process proceeds to step 116 in FIG.

  On the other hand, if the Y-axis is the main axis, in step 308, the start point correction determination unit 62 determines which position of the diamond frame Dm the coordinates of the start point of the next line (the coordinates of the end point of the previous line) are outside the frame. If the coordinates of the start point of the next line is outside the upper left or upper right frame, the process proceeds to step 310 to determine whether the drawing direction of the next line is positive. Here, when the coordinates of the start point of the next line are out of the upper left or upper right frame and the drawing direction of the next line is positive, the pixel including the start point of the next line is drawn, that is, hit twice. Therefore, the determination in step 310 can be said to be a process of determining whether or not to strike twice, that is, whether or not the start point needs to be corrected. If the drawing direction of the next line is positive and the start point of the next line needs to be corrected, the process proceeds to step 406, where the drawing direction of the next line is negative and the start point of the next line need not be corrected. If so, the process proceeds to step 116 in FIG.

  If the coordinates of the start point of the next line is outside the lower left or lower right frame, the process proceeds to step 312 to determine whether the drawing direction of the next line is negative. Here, when the coordinates of the start point of the next line are out of the lower left or lower right frame and the drawing direction of the next line is negative, the pixel including the start point of the next line is drawn, that is, hit twice. Therefore, the determination in step 312 can be said to be a process of determining whether or not to strike twice, that is, whether or not the start point needs to be corrected. If the drawing direction of the next line is negative and the start point of the next line needs to be corrected, the process proceeds to step 408, where the drawing direction of the next line is positive and the start point of the next line need not be corrected. Then, the process proceeds to step 116 in FIG.

  In step 112 of FIG. 5, when the coordinate correction processing unit 64 determines that the start point of the next line needs to be corrected, the coordinate of the start point of the next line is corrected to the coordinates in the pixel adjacent to the pixel including the start point. To do. Specifically, the coordinate correction processing unit 64 executes the processing of steps 400 to 410 in FIG.

  When the coordinates of the start point of the next line are outside the lower left or lower left frame and the drawing direction of the next line is positive, in step 400 of FIG. 8, the coordinate correction processing unit 64 corrects the X coordinate of the start point of the next line. For example, if the X coordinate of the starting point of the next line is Xs, the corrected X coordinate AXs is calculated by the following equation.

AXs = Xs + a (2)

Here, a is a predetermined correction amount, for example, 1.0 is set. When a = 1.0, the X coordinate is corrected by one pixel in the positive direction. The correction amount is not limited to this, and may be a value for correcting to the center of adjacent pixels, for example.

  When the coordinates of the start point of the next line are outside the upper right or lower right frame and the drawing direction of the next line is negative, in step 402, the coordinate correction processing unit 64 corrects the X coordinate of the start point of the next line. For example, if the X coordinate of the starting point of the next line is Xs, the corrected X coordinate AXs is calculated by the following equation.

AXs = Xs−a (3)

Here, a is set to 1.0, for example. When a = 1.0, the X coordinate is corrected by one pixel in the negative direction.

  As described above, the coordinate correction processing unit 64 corrects the X coordinate in the positive direction if the drawing direction of the next line is positive, and corrects the X coordinate in the negative direction if the drawing direction of the next line is negative. .

  In step 404, the coordinate correction processing unit 64 corrects the Y coordinate of the start point of the next line. For example, if the Y coordinate of the start point of the next line is Ys, the corrected Y coordinate AYs is calculated by the following equation.

AYs = Ys + (b1 × a) (4)

Here, b1 is the inclination of the next line, that is, the ratio of the change amount of the Y coordinate to the unit increase amount of the X coordinate. For example, 1.0 is set for a. When a = 1.0, if the slope b1 is a positive value, the Y coordinate is corrected in the positive direction by one pixel. If the slope b1 is a negative value, the Y coordinate is corrected in the negative direction by one pixel.

  If the coordinates of the start point of the next line are outside the upper left or upper right frame and the drawing direction of the next line is positive, in step 406, the coordinate correction processing unit 64 corrects the Y coordinate of the start point of the next line. For example, if the Y coordinate of the start point of the next line is Ys, the corrected X coordinate AYs is calculated by the following equation.

AYs = Ys + a (5)

Here, a is set to 1.0, for example. When a = 1.0, the Y coordinate is corrected by one pixel in the positive direction.

  When the coordinates of the start point of the next line are outside the lower left or lower right frame and the drawing direction of the next line is negative, in step 408, the coordinate correction processing unit 64 corrects the Y coordinate of the start point of the next line. For example, if the Y coordinate of the start point of the next line is Ys, the corrected Y coordinate AYs is calculated by the following equation.

AYs = Ys−a (6)

Here, a is set to 1.0, for example. When a = 1.0, the Y coordinate is corrected by one pixel in the negative direction.

  As described above, the coordinate correction processing unit 64 corrects the Y coordinate in the positive direction if the drawing direction of the next line is positive, and corrects the Y coordinate in the negative direction if the drawing direction of the next line is negative. .

  In step 410, the X coordinate of the start point of the next line is corrected. For example, if the X coordinate of the starting point of the next line is Xs, the corrected X coordinate AXs is calculated by the following equation.

AXs = Xs + (b2 × a) (7)

Here, b2 is the inclination of the next line, that is, the ratio of the change amount of the X coordinate to the unit increase amount of the Y coordinate. a is a predetermined correction amount, for example, 1.0 is set. When a = 1.0, if the slope b2 is a positive value, the X coordinate is corrected in the positive direction by one pixel. If the slope b2 is a negative value, the X coordinate is corrected in the negative direction by one pixel.

  FIG. 9 shows an example when the coordinates of the start point of the next line are corrected. As shown in the figure, when the end point E11 of the previous line (first line) L11 is outside the upper right frame of the diamond frame Dm, the drawing direction of the next line (second line) L21 whose main axis is the Y axis is the positive direction. In this case, the Y coordinate of the start point S21 of the next line L21 is corrected by the above equation (5). In FIG. 9, since the correction amount a is corrected as a = 1.0, the Y coordinate of the start point S21 of the next line L21 is corrected by one pixel in the downward direction in FIG. Further, the X coordinate of the starting point S21 of the next line L21 is corrected by the above equation (7). That is, the X coordinate of the start point S21 of the next line L21 is corrected by (the inclination of the next line L21 × 1.0). Thereby, the starting point S21 of the next line L21 is corrected to the starting point S22. For the next lines L23 and L24, it is not necessary to correct the start point of the next line.

  As shown in the figure, when the end point E11 of the previous line L11 is outside the upper right frame of the diamond frame Dm, and the drawing direction of the next line L22 whose principal axis is the X axis is the negative direction, the start point of the next line L22 The X coordinate of S21 is corrected by the above equation (3). In FIG. 9, since the correction amount a is corrected with a = 1.0, the X coordinate of the start point S21 of the next line L22 is corrected by one pixel in the left direction in the figure. Further, the Y coordinate of the starting point S21 of the next line L22 is corrected by the above equation (4). That is, the Y coordinate of the start point S21 of the next line L22 is corrected by (the inclination of the next line × 1.0). Thereby, the starting point S21 of the next line L22 is corrected to the starting point S23.

  Also, as shown in the figure, when the end point E12 of the previous line L12 is outside the lower left frame of the Diamond frame Dm, and the drawing direction of the next line L25 whose Y axis is the main axis is the negative direction, the start point of the next line L25 The Y coordinate of S24 is corrected by the above equation (6). In FIG. 9, since the correction amount a is corrected as a = 1.0, the Y coordinate of the start point S24 of the next line L25 is corrected by one pixel in the upward direction in FIG. Further, the X coordinate of the start point S24 of the next line L25 is corrected by the above equation (7). That is, the X coordinate of the starting point S24 of the next line L25 is corrected by (the inclination of the next line L25 × 1.0). Thereby, the starting point S24 of the next line L25 is corrected to the starting point S25.

  As shown in the figure, when the end point E12 of the previous line L12 is outside the lower left frame of the diamond frame Dm, and the drawing direction of the next line L26 whose main axis is the X axis is the positive direction, the start point of the next line L26 The X coordinate of S24 is corrected by the above equation (2). In FIG. 9, since the correction amount a is corrected as a = 1.0, the X coordinate of the start point S24 of the next line L26 is corrected by one pixel in the right direction in the figure. Further, the Y coordinate of the starting point S24 of the next line L26 is corrected by the above equation (4). That is, the Y coordinate of the starting point S24 of the next line L26 is corrected by (the inclination of the next line L26 × 1.0). As a result, the starting point S24 of the next line L26 is corrected to the starting point S26. For the next lines L27 and L28, it is not necessary to correct the start point of the next line.

  After correcting the start point of the next line as described above, the routine proceeds to step 114 in FIG.

  In step 114 of FIG. 5, when the length of the next line in the principal axis direction is 1 pixel or more, the line disappearance determination unit 66 determines the coordinates of the start point of the next line corrected by the coordinate correction processing unit 64 as the DER processing unit 50. Output to. Further, the line disappearance determination unit 66 determines that the next line should be lost when the length of the next line in the principal axis direction is less than 1 pixel, and causes the DER processing unit 50 not to draw the next line. Notice. Specifically, the line disappearance determination unit 66 executes a line disappearance determination process shown in FIG.

  As shown in FIG. 10, in step 500, the line disappearance determination unit 66 determines the drawing direction of the next line after the start point correction based on the coordinates of the start point after the correction of the next line and the coordinates of the end point of the next line. calculate. The determination of the drawing direction is the same as step 104 in FIG. In other words, when the X direction of the next line after correction is the main axis, if the value obtained by subtracting the X coordinate of the start point after correction from the X coordinate of the end point is a positive value, the drawing direction of the next line after correction is the positive direction It is determined that Further, if the negative value is obtained by subtracting the X coordinate of the corrected start point from the X coordinate of the end point, the drawing direction of the next line after correction is determined to be a negative direction.

  In step 502, the drawing direction of the next line before correcting the coordinates of the starting point is compared with the drawing direction of the next line after correcting the starting point. That is, the drawing direction of the next line before correction calculated in steps 304, 306, 310, and 312 in FIG. 7 is compared with the drawing direction of the next line after correcting the start point calculated in step 500.

  In step 504, the line disappearance determination unit 66 determines whether or not the drawing direction of the next line before the start point is corrected and the drawing direction of the next line after the start point is corrected are the same. If so, the process proceeds to step 506, and if not identical, the process proceeds to step 508.

  In step 506, the line disappearance determination unit 66 outputs the coordinate data of the start point of the next line after correcting the start point to the DER processing unit 50. In step 116 of FIG. 5, the DER processing unit 50 executes DER processing based on the coordinate data of the start point of the next line after correction, and draws the drawing information (start point and end point coordinates, line inclination value, line length). , Main axis information, etc.) and output to the selector 54. The DER processing unit 50 outputs the coordinate data of the end point of the previous line to the end point drawing determination unit 60 as the coordinate data of the start point of the next line. Thus, when the process of FIG. 5 is executed next time, in step 106, the end point drawing determination process is executed using the coordinate data of the end point of the previous line as the coordinate data of the start point of the next line.

  On the other hand, in step 508, it is determined that the next line has disappeared, and a notification to that effect is sent to the next coordinate data processing. When the selection unit 54 is not notified of the disappearance of the line from the line disappearance determination unit 66, the selection unit 54 outputs the drawing information from the DER processing unit 50, and is notified of the disappearance of the line from the line disappearance determination unit 66. In the case where the DER processing unit 50 has received, the drawing information from the DER processing unit 50 is not output.

  FIG. 11 shows an example where the next line disappears. As shown in the figure, when the end point E1 of the front line L1 whose main axis is the Y axis and the drawing direction is the positive direction is outside the lower left frame of the Diamond frame Dm, the pixel PXL including the end point E1 is determined to be drawn.

  And, for example, when the main axes of the next lines L21 to L23 are the X axis and the drawing direction is the positive direction, as in the case of the end points E21 to E23 of the next lines L21 to L23, the start point S2 of the next lines L21 to L23 is Correction is made to the start points S21 to S23 in the adjacent pixels.

  Also, as in the case of the end points E24 to L26 of the next lines L24 to L26, when the main axis of the next lines L24 to L26 is the Y axis and the drawing direction is negative, the start point S2 of the next lines L24 to L26 is adjacent. The starting points S24 to S26 in the pixel to be corrected are corrected.

  Here, since the next lines L21 to L26 before the start point is corrected have a length in the main axis direction of less than one pixel, they are the same as the drawing directions of the next lines L21 ′ to L26 ′ after the start point is corrected. is not. For this reason, the next lines L21 to L26 are determined to disappear.

  FIG. 12 shows another example where the next line disappears. This figure is the same as FIG. 11 except that the main axis of the front line L1 is the X axis and the drawing direction is the negative direction. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 13 shows another example when the next line disappears. This figure is the same as FIG. 11 except that the main axis of the front line L1 is the Y axis and the drawing direction is the positive direction, and the end point E1 of the front line L1 is outside the lower right frame of the Diamond frame Dm. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 14 shows another example when the next line disappears. This figure is the same as FIG. 13 except that the main axis of the front line L1 is the X axis and the drawing direction is the positive direction. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 15 shows another example in which the next line disappears. This figure is the same as FIG. 11 except that the main axis of the front line L1 is the Y axis and the drawing direction is negative, and the end point E1 of the front line L1 is outside the upper left frame of the Diamond frame Dm. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 16 shows another example when the next line disappears. This figure is the same as FIG. 15 except that the main axis of the front line L1 is the X axis and the drawing direction is the negative direction. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 17 shows another example in which the next line disappears. This figure is the same as FIG. 11 except that the main axis of the front line L1 is the Y axis and the drawing direction is negative, and the end point E1 of the front line L1 is outside the upper right frame of the Diamond frame Dm. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  FIG. 18 shows another example where the next line disappears. This figure is the same as FIG. 17 except that the main axis of the front line L1 is the X axis and the drawing direction is the positive direction. Also in this case, the lengths of the next lines L21 to L26 before correction are all less than one pixel, and the drawing directions before and after correction are not the same, so that all the lines are determined to disappear.

  As described above, in this embodiment, when the DiamondExitRule is applied as it is, the end point of the previous line, that is, the pixel including the start point of the next line is hit twice, the coordinates of the start point of the next line are set in the adjacent pixels. Correct to coordinates. For this reason, as shown in FIG. 19, it is possible to prevent the pixel PXL including the end point E1 of the previous line L1 (start point S2 of the next line L2) from being hit twice.

  Also, if the difference between the start point coordinate and the end point coordinate of the next line in the main axis direction is less than 1 pixel, applying DiamondExitRule with the start point of the next line corrected will result in the pixels including the start point of the corrected next line. Will draw. On the other hand, in this embodiment, when the length of the next line in the principal axis direction is less than 1 pixel, that is, when the drawing direction of the next line before and after correction is not the same, the next line is treated as having been lost. It is possible to prevent extra pixels from being drawn.

  In the present embodiment, it is determined whether the length of the next line before correction in the main axis direction is less than 1 pixel by determining whether the drawing direction of the next line before and after correction is the same. However, the determination method is not limited to this. For example, the length in the main axis direction of the next line before correction is calculated based on the coordinates of the start point and end point of the next line before correction, and if the length is less than 1 pixel, the next line is treated as lost. It may be.

  Further, in the present embodiment, the case where the pixel passing through the line from the inside of the diamond frame Dm to the outside of the frame is described, but the pixel passing through the line from the outside of the diamond frame Dm to the inside of the frame is drawn. Also good.

  Further, in this embodiment, the case of drawing a continuous line using DiamondExitRule has been described. However, if the rule draws a pixel that intersects at least once in a pixel with a frame preset in the pixel, It is not limited. For example, the frame set in the pixel is not limited to a diamond frame, that is, a diamond-shaped frame, but may be a polygonal shape such as a triangle or a pentagon, or a shape including a curve such as a circle.

  In the above description, the line drawing program 80, which is an example of the line drawing program according to the disclosed technique, is stored (installed) in the storage unit 76 in advance. However, the present invention is not limited to this. The image processing program according to the disclosed technology can be provided in a form recorded on a recording medium such as a CD-ROM or a DVD-ROM.

  All documents, patent applications and technical standards mentioned in this specification are to the same extent as if each individual document, patent application and technical standard were specifically and individually stated to be incorporated by reference. Incorporated by reference in the book.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. A drawing information generation unit that generates first drawing information for drawing;
An end point drawing determination unit for determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line; ,
When the drawing determination unit determines to draw the pixel including the end point of the first line, the coordinates of the start point of the second line, which is the end point of the first line, and the coordinates of the end point of the second line And determining whether the second line start point coordinate needs to be corrected based on the second line start point coordinate and the second line drawing direction. A starting point correction determination unit for determining;
A coordinate correction processing unit that corrects the coordinates of the start point of the second line to the coordinates in the pixel adjacent to the pixel including the start point when it is determined that the correction of the start point of the second line is necessary;
When the length of the second line in the principal axis direction is 1 pixel or more, the coordinates of the start point of the second line corrected by the coordinate correction processing unit are output as second drawing information, When the length in the main axis direction is less than 1 pixel, a line disappearance determination unit that determines that the second line should be disappeared and makes the second line non-drawn;
A drawing processing unit for performing drawing processing based on the first drawing information or the second drawing information;
A line drawing apparatus comprising:

(Appendix 2)
The line disappearance determination unit has the same drawing direction of the second line before correcting the starting point of the second line and the drawing direction of the second line after correcting the starting point of the second line. If it is the same, it is determined that the length of the second line in the principal axis direction is 1 pixel or more. If not, the length of the next line in the principal axis direction is 1 The line drawing apparatus according to appendix 1, wherein the line drawing device is determined to be less than a pixel.

(Appendix 3)
Based on the coordinates of the start point and the end point, a main axis determination unit that determines whether the main axis of the line connecting the start point and the end point is the X axis or the Y axis orthogonal to the X axis;
A drawing direction determination unit that determines a drawing direction of the line based on each of the X coordinate and the Y coordinate of the start point and the end point of the line;
The line drawing apparatus according to Supplementary Note 1 or Supplementary Note 2, characterized by comprising:

(Appendix 4)
The end point drawing determination unit includes the main axis of the first line determined by the main axis determination unit, the position of the end point of the first line in the pixel, and the first line determined by the drawing determination unit. The line drawing apparatus according to claim 3, wherein whether or not to draw a pixel including the end point of the first line is determined based on a drawing direction.

(Appendix 5)
When it is determined that the end point of the first line is drawn, the start point correction determination unit determines the main axis of the second line determined by the main axis determination unit and the second determined by the drawing direction determination unit. The supplementary note 3 or 3, wherein whether or not the correction of the coordinates of the start point of the second line is necessary is determined based on the drawing direction of the line and the position in the pixel of the start point of the second line. The line drawing apparatus according to appendix 4.

(Appendix 6)
When the principal axis of the second line is the X axis, the coordinate correction processing unit corrects the X coordinate of the start point of the second line by one pixel and sets the Y coordinate of the start point of the second line to the second If the main axis of the second line is the Y axis, the Y coordinate of the starting point of the second line is corrected by one pixel and the X coordinate of the starting point of the second line is corrected. The line drawing apparatus according to any one of appendices 1 to 5, wherein correction is performed in accordance with an inclination of the second line.
(Appendix 7)
The drawing rule is a rule for drawing a pixel in which a first line connecting the start point and the end point intersects with a frame preset in the pixel at least once in the pixel. The line drawing apparatus according to any one of 6.

(Appendix 8)
Computer
The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. Generating first drawing information for drawing;
Determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line;
When it is determined that the pixel including the end point of the first line is to be drawn, the second line is determined based on the coordinates of the start point of the second line, which is the end point of the first line, and the end point of the second line. Determining the drawing direction of the line, determining whether or not the correction of the coordinates of the starting point of the second line is necessary based on the coordinates of the starting point of the second line and the drawing direction of the second line;
If it is determined that the correction of the coordinates of the start point of the second line is necessary, the coordinates of the start point of the second line are corrected to the coordinates in the pixel adjacent to the pixel including the start point;
When the length of the second line in the principal axis direction is 1 pixel or more, the corrected coordinates of the start point of the second line are output as second drawing information, and the length of the second line in the principal axis direction is If it is less than one pixel, it is determined that the second line should be lost, the second line is not drawn,
A line drawing method comprising: performing drawing processing based on the first drawing information or the second drawing information.

(Appendix 9)
It is determined whether the drawing direction of the second line before correcting the starting point of the second line is the same as the drawing direction of the second line after correcting the starting point of the second line. When the length is the same, it is determined that the length of the second line in the principal axis direction is 1 pixel or more. When the length is not the same, the length of the next line is determined to be less than one pixel. The line drawing method according to appendix 8, wherein

(Appendix 10)
Based on the coordinates of the start point and the end point, determine whether the main axis of the line connecting the start point and the end point is the X axis or the Y axis orthogonal to the X axis,
The line drawing method according to claim 8 or 9, wherein a drawing direction of the line is determined based on each of the X coordinate and the Y coordinate of the start point and the end point of the line.

(Appendix 11)
Based on the determined principal axis of the first line, the position of the end point of the first line in the pixel, and the drawing direction of the first line determined by the drawing determining unit. The line drawing method according to claim 10, wherein it is determined whether or not to draw a pixel including the end point.

(Appendix 12)
When it is determined to draw the end point of the first line, based on the main axis of the second line, the drawing direction of the second line, and the position in the pixel of the start point of the second line, The line drawing method according to appendix 10 or appendix 11, wherein it is determined whether or not correction of the coordinates of the start point of the second line is necessary.

(Appendix 13)
When the main axis of the second line is the X-axis, the X coordinate of the start point of the second line is corrected by one pixel, and the Y coordinate of the start point of the second line is divided according to the inclination of the second line. When the principal axis of the second line is the Y axis, the Y coordinate of the starting point of the second line is corrected by one pixel, and the X coordinate of the starting point of the second line is changed to the inclination of the second line. The line drawing method according to any one of appendices 8 to 12, wherein correction is performed in accordance with the amount corresponding thereto.

(Appendix 14)
The drawing rule is a rule for drawing a pixel in which a first line connecting the start point and the end point intersects with a frame preset in the pixel at least once in the pixel. 14. The line drawing apparatus according to any one of items 13.

(Appendix 15)
On the computer,
The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. Generating first drawing information for drawing;
Determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line;
When it is determined that the pixel including the end point of the first line is to be drawn, the second line is determined based on the coordinates of the start point of the second line, which is the end point of the first line, and the end point of the second line. Determining the drawing direction of the line, determining whether or not the correction of the coordinates of the starting point of the second line is necessary based on the coordinates of the starting point of the second line and the drawing direction of the second line;
If it is determined that the correction of the coordinates of the start point of the second line is necessary, the coordinates of the start point of the second line are corrected to the coordinates in the pixel adjacent to the pixel including the start point;
When the length of the second line in the principal axis direction is 1 pixel or more, the corrected coordinates of the start point of the second line are output as second drawing information, and the length of the second line in the principal axis direction is If it is less than one pixel, it is determined that the second line should be lost, the second line is not drawn,
A line drawing program for executing processing including performing drawing processing based on the first drawing information or the second drawing information.

DESCRIPTION OF SYMBOLS 10 Drawing apparatus 12 Vertex processing part 16 Drawing processing part 18 Triangle setup part 20 Line setup part 22 Select part 50 DER processing part 52 Line drawing determination part 54 Select part 56 Drawing direction determination part 58 Main axis determination part 60 End point drawing determination part 62 Start point Correction determination unit 64 Coordinate correction processing unit 66 Line disappearance determination unit 70 Computer 74 Memory 76 Storage unit

Claims (9)

The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. A drawing information generation unit that generates first drawing information for drawing;
An end point drawing determination unit for determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line; ,
When the drawing determination unit determines to draw the pixel including the end point of the first line, the coordinates of the start point of the second line, which is the end point of the first line, and the coordinates of the end point of the second line And determining whether the second line start point coordinate needs to be corrected based on the second line start point coordinate and the second line drawing direction. A starting point correction determination unit for determining;
A coordinate correction processing unit that corrects the coordinates of the start point of the second line to the coordinates in the pixel adjacent to the pixel including the start point when it is determined that the correction of the start point of the second line is necessary;
When the length of the second line in the principal axis direction is 1 pixel or more, the coordinates of the start point of the second line corrected by the coordinate correction processing unit are output as second drawing information, When the length in the main axis direction is less than 1 pixel, a line disappearance determination unit that determines that the second line should be disappeared and makes the second line non-drawn;
A drawing processing unit for performing drawing processing based on the first drawing information or the second drawing information;
A line drawing apparatus comprising: The line disappearance determination unit has the same drawing direction of the second line before correcting the starting point of the second line and the drawing direction of the second line after correcting the starting point of the second line. If it is the same, it is determined that the length of the second line in the principal axis direction is 1 pixel or more. If not, the length of the next line in the principal axis direction is 1 The line drawing device according to claim 1, wherein the line drawing device is determined to be less than a pixel. Based on the coordinates of the start point and the end point, a main axis determination unit that determines whether the main axis of the line connecting the start point and the end point is the X axis or the Y axis orthogonal to the X axis;
A drawing direction determination unit that determines a drawing direction of the line based on each of the X coordinate and the Y coordinate of the start point and the end point of the line;
The line drawing apparatus according to claim 1, further comprising: The end point drawing determination unit includes the main axis of the first line determined by the main axis determination unit, the position of the end point of the first line in the pixel, and the first line determined by the drawing determination unit. The line drawing apparatus according to claim 3, wherein it is determined whether or not to draw a pixel including an end point of the first line based on a drawing direction. When it is determined that the end point of the first line is drawn, the start point correction determination unit determines the main axis of the second line determined by the main axis determination unit and the second determined by the drawing direction determination unit. 4. It is determined whether correction of the coordinates of the start point of the second line is necessary based on the drawing direction of the line and the position of the start point of the second line in the pixel. Or the line drawing apparatus of Claim 4. When the principal axis of the second line is the X axis, the coordinate correction processing unit corrects the X coordinate of the start point of the second line by one pixel and sets the Y coordinate of the start point of the second line to the second If the main axis of the second line is the Y axis, the Y coordinate of the starting point of the second line is corrected by one pixel and the X coordinate of the starting point of the second line is corrected. The line drawing apparatus according to claim 3, wherein correction is performed in accordance with an inclination of the second line. The drawing rule is a rule for drawing a pixel in which a first line connecting the start point and the end point intersects a frame set in advance in the pixel at least once in the pixel. The line drawing apparatus according to claim 1. Computer
The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. Generating first drawing information for drawing;
Determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line;
When it is determined that the pixel including the end point of the first line is to be drawn, the second line is determined based on the coordinates of the start point of the second line, which is the end point of the first line, and the end point of the second line. Determining the drawing direction of the line, determining whether or not the correction of the coordinates of the starting point of the second line is necessary based on the coordinates of the starting point of the second line and the drawing direction of the second line;
If it is determined that the correction of the coordinates of the start point of the second line is necessary, the coordinates of the start point of the second line are corrected to the coordinates in the pixel adjacent to the pixel including the start point;
When the length of the second line in the principal axis direction is 1 pixel or more, the corrected coordinates of the start point of the second line are output as second drawing information, and the length of the second line in the principal axis direction is If it is less than one pixel, it is determined that the second line should be lost, the second line is not drawn,
A line drawing method comprising: performing drawing processing based on the first drawing information or the second drawing information. On the computer,
The coordinate information of the first and second lines is input, the drawing information of the first line is generated based on the drawing rule, and the end point of the first line is continuously used as the starting point of the second line to be drawn next. Generating first drawing information for drawing;
Determining whether to draw the pixel including the end point of the first line based on the coordinates in the pixel region including the end point of the first line and the drawing direction of the first line;
When it is determined that the pixel including the end point of the first line is to be drawn, the second line is determined based on the coordinates of the start point of the second line, which is the end point of the first line, and the end point of the second line. Determining the drawing direction of the line, determining whether or not the correction of the coordinates of the starting point of the second line is necessary based on the coordinates of the starting point of the second line and the drawing direction of the second line;
If it is determined that the correction of the coordinates of the start point of the second line is necessary, the coordinates of the start point of the second line are corrected to the coordinates in the pixel adjacent to the pixel including the start point;
When the length of the second line in the principal axis direction is 1 pixel or more, the corrected coordinates of the start point of the second line are output as second drawing information, and the length of the second line in the principal axis direction is If it is less than one pixel, it is determined that the second line should be lost, the second line is not drawn,
A line drawing program for executing processing including performing drawing processing based on the first drawing information or the second drawing information.