JP2004078994A - Drawing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drawing method for performing highly precise drawing with small-scale hardware. <P>SOLUTION: Indentation of an object constituted of a polygon is eliminated by overwriting a segment connecting apexes corresponding to a contour part of the polygon for the contour part of the polygon drawn in a frame memory. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a drawing method used for a computer graphics system which is a video device using a computer, a special effect device, a video game machine, and the like.

For example, in a home TV game machine, a personal computer, a computer graphics system, or the like, a television receiver, a monitor receiver, or a cathode ray tube (CRT)
In an image generating apparatus that generates image data to be output to a display device such as a Ray Tube (display) device, that is, display output image data, a central processing unit (CPU: Central Processing Unit)
By providing a dedicated drawing device between the processing unit and the frame buffer, high-speed processing is possible.

That is, when the three-dimensional image is generated by the image generation device, the CPU does not directly access the frame buffer, but performs geometry processing such as coordinate conversion, clipping, and light source calculation to obtain a multi-dimensional image such as a triangle or a quadrangle. A drawing command for drawing a three-dimensional image by defining a three-dimensional shape as a combination of polygons (polygons) is generated, and the drawing command is transferred to the drawing device.

More specifically, for example, when generating an image of a three-dimensional object 200 as shown in FIG. 11, the CPU first defines the object 200 as a combination of polygons _{P201, P202} , and _P203 .

Then, CPU generates a drawing instruction corresponding to each polygon P _201, P _202, P ₂₀₃ for drawing a three-dimensional image based on the object 200, and transfers the drawing instructions to the drawing device.

The drawing device interprets the drawing command transferred from the CPU and, based on the color data of the vertices and the Z value indicating the depth, considers the colors and Z values of all the pixels constituting the polygon, and stores the pixel data in the frame buffer. Performs rendering processing to write in the frame buffer, and draws a figure in the frame buffer.

The Z value is information indicating the distance from the viewpoint in the depth direction.

That is, the drawing apparatus, for example, when drawing a polygon P ₂₀₁ shown in among 12 of the polygon P _201, P _202, P ₂₀₃ constituting the object 200, first, by interpreting the drawing command from CPU, FIG. As shown in FIG. 13, the Y coordinates y ₁ , y of the four vertices (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ) and (x ₄ , y ₄ ) of the polygon P _{201 2} , y ₃ and y ₄ are obtained, and the maximum value Y _max (= y ₃ ) and the minimum value Y _min (= y ₁ ) of the Y coordinate are obtained.

Here, as shown in FIG. 14, the pixels Dn in the frame buffer 300 are arranged in a grid, but the four vertices (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ ) of the polygon P ₂₀₁ , Y ₃ ), (x ₄ , y ₄ ) do not always match the grid points.

Therefore, the drawing apparatus performs a value truncation process and a round-up process on the minimum value Y _min and the maximum value Y _max of the Y coordinate, and obtains horizontal pixel lines L _{H2 to} L _H17 that intersect the polygon P _201. . The drawing device obtains an intersection of the polygon P ₂₀₁ and the horizontal pixel line L _H2 ~L _H17.

The rendering device, for values of X-coordinate of the intersection point, performs truncation processing of the values, the maximum value X _max and minimum value X _min of the X coordinates of pixels included in the polygon P _201.

Then, the drawing apparatus writes pixels included in the range of the minimum value X _min to the maximum value X _max of the X coordinate in the horizontal pixel lines L _{H2 to} L _H17 into the frame buffer for each horizontal pixel line.

However, as a result of the polygon P ₂₀₁ being drawn in the frame buffer by the conventional drawing apparatus as described above, as shown in FIG. 15, the boundary (edge) E of the polygon P ₂₀₁ is in a jagged state (hereinafter referred to as a jagged state). .)

Therefore, in the above-described drawing apparatus, for example, a sub-pixel method, a background mixing method, or the like is employed as a method for removing the jaggedness.

The sub-pixel method is a method of drawing polygons in a frame buffer at a resolution higher than the actual display resolution, and finally applying a low-pass filter to reduce the actual display resolution, thereby removing jaggies.

More specifically, FIG. 16A shows that the polygon P ₂₀₁ shown in FIG. 12 is frame buffered at twice the display resolution in each of the horizontal (H) direction and the vertical (V) direction. FIG. 7 is a diagram showing a state where the image is drawn. That one pixel (pixel) D _n of the frame buffer corresponds to 2 × 2 sub-pixel SD _n1 to SD _n4 pixels. Therefore, a plurality of colors are included in the sub-pixels SD _{n1 to} SD _n4 . Therefore, an average value of a plurality of colors included in the sub-pixels SD _{n1 to} SD _n4 is obtained for each pixel, and the average value is used as the color of the display pixel.

For example, as shown in FIG. 16 (a), when the color of the background B and the polygon P ₂₀₁ are each one color, the average value of a plurality of colors included in the sub-pixels SD _n1 to SD _n4 is sub pixels SD _n1 to SD _n4 color of all the background B, the sub-pixels SD _n1 to SD 1 only subpixel polygon P ₂₀₁ colors out of _n4, 2 only subpixel polygon P ₂₀₁ of the sub-pixels SD _n1 to SD _n4 color, either 3 colors only subpixels polygon P _201, and the sub-pixels SD _n1 to SD _n4 all of the color out of 5 obtained from the color of the polygon P ₂₀₁ of the sub-pixels SD _n1 to SD _n4 Take.

Therefore, as shown in FIG. 16B, the polygon _P201 is drawn on the frame buffer by display pixels having five levels of colors.

However, in the conventional drawing apparatus employing the above-described sub-pixel method, it is necessary to perform drawing at a resolution higher than the actual display resolution, and thus it is necessary to provide a frame buffer having a higher resolution than the actual display resolution. . As a result, the hardware scale of the drawing apparatus has been increased.

On the other hand, when the true edge of a polygon intersects a pixel, the background mixing method determines the ratio of the inside of the polygon to the pixel, and mixes the polygon color and the background color at that ratio. , Is a method of removing jaggedness.

Specifically, first, FIG. 17 is a diagram showing a state in which drawing the polygon P ₂₀₁ shown in FIG. 12 by removing the jaggies by the background mixing method in the frame buffer.

For example, as shown in FIG. 17, when the color of the background B is “green” and the color of the polygon P ₂₀₁ is “blue”, the color of the pixel of the edge E1 of the polygon P ₂₀₁ is “green”. It becomes.

Further, as shown in FIG. 18, when the “red” polygon P ₂₀₂ is drawn adjacent to the polygon P ₂₀₁ , the color of the pixel of the edge E ₂ of the polygon P ₂₀₂ becomes “green-red” and the polygon P ₂₀₂ the color of the pixel of the edge E _{12 to 201} and the polygon P ₂₀₂ is shared, the addition of "red" color of a pixel of the edge E1 "patina""patinared".

Here, the edge E ₁₂ polygon P ₂₀₁ and the polygon P ₂₀₂ share, because the background B should not be seen, but the color of the pixel of the edge E ₁₂ should be "blue red", as described above In addition, the color of the pixel at the edge E12 becomes "green, blue and red", and the color of the background B appears.

In other words, in the conventional drawing apparatus that employs the background mixing method as described above, the background color is blurred because the background color that cannot be seen is mixed with the edge color.

Therefore, the present invention has been made in view of the above-described conventional circumstances, and has the following objects.

That is, an object of the present invention is to provide a drawing method capable of performing high-precision drawing with small-scale hardware.

In order to solve the above-described problem, a drawing method according to the present invention is a drawing method for drawing shape data composed of polygons generated by computer graphics on a frame memory, wherein the drawing data is drawn on the frame memory. A line segment connecting vertices corresponding to the polygonal contour portion is overwritten on the polygonal contour portion.
For example, the drawing method according to the present invention is a drawing method executed by a drawing device that draws an image including a polygon, which is a polygon, on a frame memory based on a drawing command from a CPU. A first process of drawing a polygon on a frame memory based on a drawing command from a CPU, and overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting vertices of the polygon. And in the first step, in the first step, a plurality of the polygons are adjacent to each other, and are drawn in order so that those adjacent to each other share a vertex, When a part of the outline of these polygons overlaps the outline of an adjacent polygon, the polygon drawn earlier is overwritten by the polygon drawn later. In both cases, in the second step, a pixel value of a pixel on which the line segment having the predetermined width is drawn is determined based on pixel values of pixels on two polygons adjacent to the pixel, and the determined pixel value is determined. It is assumed that the line segment is overwritten using the pixel value.
Alternatively, a drawing method executed by a drawing device that draws an image including a polygon, which is a polygon, on a frame memory based on a drawing command from the CPU, wherein the drawing device performs A first step of drawing a polygon on a frame memory, a second step of overwriting a drawn line of the polygon with a line segment having a predetermined width connecting the vertices of the polygon, When a plurality of polygons are sequentially drawn in the first step, when a part of the polygon to be drawn overlaps a part of an adjacent polygon, a polygon to be drawn later is used. In the second step, the pixel value of the pixel on which the line segment having the predetermined width is drawn is set in the second step. It determined based on the pixel values of the pixels of two polygons that are adjacent to the element, overwriting by the line segment using the determined its pixel value may be a thing.
Further, the drawing apparatus of the present invention is a drawing apparatus that draws an image including polygons on a frame memory based on a drawing command from a CPU, for example, based on a drawing command from the CPU. A first means for drawing a polygon on a frame memory, and a second means for overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting vertices of the polygon. The first means may include, when the plurality of polygons are adjacent to each other, and are drawn in order so that adjacent ones share vertices, when the outline portions of the polygons are adjacent polygons. When overlapping with the outline portion, the polygon drawn earlier is overwritten by the polygon drawn later, and the second means is A pixel value of a pixel on which the line segment having the predetermined width is drawn is determined based on pixel values of pixels on two polygons adjacent to the pixel, and the determined pixel value is used to determine the pixel value of the line segment. Overwriting can be performed.
Alternatively, a drawing device for drawing an image including a polygon, which is a polygon, on a frame memory based on a drawing command from a PU, and drawing the polygon on the frame memory based on a drawing command from the CPU. First means, and second means for overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting the vertices of the polygon, wherein the first means When part of the polygon to be drawn overlaps with part of an adjacent polygon when a plurality of polygons are drawn in order, a part of the polygon drawn first by the polygon drawn later is While both are overwritten,
The second means determines a pixel value of a pixel on which the line segment having the predetermined width is drawn based on pixel values of pixels of two polygons adjacent to the pixel, and determines the determined pixel value. Overwriting with the line segment.
In these methods, the drawing processing without the jagged removal is performed, and then the jagged removal processing is performed. Therefore, it is possible to prevent the appearance of colors that should not be seen, such as the background color.

The drawing device sets the pixel value of the pixel on which the line segment having the predetermined width is drawn to a pixel value of a pixel adjacent to the pixel and an ideal point on a line segment connecting the vertexes of the polygon. The determination may be made based on the pixel value that should have been allocated.

In the drawing method, the line segment having the predetermined width may be drawn by a pixel passing through a line segment connecting the vertices of the polygon and a pixel adjacent thereto.

In the drawing method, the pixel value of each pixel on the line segment may be weighted, and a pixel value to be interpolated with the pixel value on the line segment may be selected according to the weight.

In the drawing method according to the present invention, the line connecting the vertices corresponding to the outline of the polygon is overwritten on the outline of the polygon drawn in the frame memory. Thus, the drawing method can easily remove the jaggedness of the entire polygonal object, and can prevent the appearance of colors that should not be seen, such as the background color. Therefore, the above-described drawing method can perform high-precision drawing with small-scale hardware.

In addition, in the drawing method according to the present invention, the line segment is overwritten on the outline portion using a pixel value adjacent to the outline portion. Thus, the drawing method can prevent background bleeding. Therefore, the above-described drawing method can perform higher-precision drawing.

In the drawing method according to the present invention, a pixel value obtained by mixing a pixel value of the background with a pixel value of the outline portion is overwritten on the outline portion overlapped by the adjacent polygon. Thus, the above-described drawing method can remove the jaggedness of the whole object constituted by polygons even when pixels which are completely overwritten by adjacent polygons occur. Therefore, the above-described drawing method can perform higher-precision drawing.

In the drawing method according to the present invention, each pixel value on the line segment is weighted, and a pixel value to be interpolated with the pixel value on the line segment is selected according to the weight. Thus, in the above-described drawing method, different values are always taken even when adjacent polygons share the same pixel. Therefore, the above-described drawing method can prevent the background from bleeding, and can perform drawing with higher precision.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

描画 The drawing method according to the present invention is performed by a drawing apparatus 100 as shown in FIG.

The drawing apparatus 100 includes a pixel engine 101, a FIFO (First in First out) buffer 102 to which an output of the pixel engine 101 is supplied, an arithmetic circuit 104 and a cache memory control circuit 103 to which an output of the FIFO buffer 102 is supplied. , A cache memory 105 to which respective outputs of the arithmetic circuit 104 and the cache memory control circuit 103 are supplied, and a frame memory 106 connected to the cache memory 105.

First, a series of operations of the drawing apparatus 100 will be described.

描画 The pixel engine 101 is supplied with a drawing command from, for example, a CPU (not shown). This drawing command is a command corresponding to each polygon for drawing a three-dimensional image by defining a three-dimensional model as a combination of basic unit figures (polygons) such as a triangle and a quadrangle and line segments.

Therefore, the pixel engine 101 interprets the drawing command from the CPU and temporarily stores the pixel data to be drawn in the FIFO buffer 102. The pixel data is, for example, data including a pixel writing position, a Z value, and a color value.

The arithmetic circuit 104 reads out the pixel data from the FIFO buffer 102 and takes the pixel data read out from the FIFO buffer 102 into the frame memory 106 via the cache memory 105 in consideration of the colors and Z values of all the pixels constituting the polygon. Write. When writing pixel data to the frame memory 106 via the cache memory 105, the arithmetic circuit 104 performs a Z-buffer process, a translucent process, an anti-aliasing process, a filtering process, and the like.

{Circle around (4)} The arithmetic circuit 104 reads pixel data from the frame memory 106 via the cache memory 105 and performs a jagged removal process on the read pixel data.

A detailed description of the jaggedness removal processing performed by the arithmetic circuit 104 will be described later.

At this time, the cache memory control circuit 103 that controls the cache memory 105 previously recognizes the data area required in the cache memory 105 by reading out the pixel data once stored in the FIFO memory 102 in advance. Then, the cache memory control circuit 103 reads the pixel data corresponding to the data area from the frame memory 106 collectively without straddling the word boundary and the page boundary of the frame memory 106, and corresponds to the data area. The cache memory 105 is controlled so that pixel data is collectively written to the frame memory 106. As a result, the cache memory 105 accesses the frame memory 106 by shortening the access time, and accesses the frame memory 106 a small number of times.

The frame memory 106 includes a Z buffer and a frame buffer (not shown). The Z buffer is a buffer that stores a Z value included in pixel data, and the frame buffer is a buffer that stores a color value included in pixel data.

Therefore, the frame memory 106 is accessed from the cache memory 105 under the control of the cache memory control circuit 103, so that the pixel data is written from the arithmetic circuit 104 via the cache memory 105, and the written pixel data is Output to the arithmetic circuit 104 via the cache memory 105.

{Circle around (4)} The frame memory 106 supplies the written pixel data, that is, the drawn pixel data, as a video signal to a television receiver, a monitor receiver, and the like (not shown).

Thereby, the television receiver, the monitor receiver, and the like display and output an image based on the pixel data from the frame memory 106.

Next, the jaggedness removal processing performed by the arithmetic circuit 104 will be specifically described.

For example, when drawing a three-dimensional model composed of four polygon P ₁ to P ₄ as shown in FIG. 2 in the frame memory 106, first, the arithmetic circuit 104, the polygon P ₁ ~ without removing jaggies the P ₄ is drawn in the frame memory 106 via cache memory 105.

Here, the frame polygon P ₁ to P ₄ which is drawn in the memory 106, for example, the edge E ₃₄ polygon P ₃ and a polygon P ₄ share an edge pixel and the edge of the pixel of the polygon P ₄ of the polygon P ₃ There duplicate, the edge E ₂₃ polygons P ₂ and the polygon P ₃ share a state in which the edge pixels of the edge pixel and polygon P ₃ of the polygon P ₂ are adjacent without overlap. That is, the polygons are arranged without gaps at the edges sharing the vertices of the polygons.

Therefore, when each polygon is drawn in the frame memory 106 in the order of the polygons P ₁ , P ₂ , P ₃ , and P ₄ , as shown in FIG. The pixel of the polygon is written.

Next, the arithmetic circuit 104, to the polygon P1~P4 drawn in the frame memory 106 without removing jaggies, connecting vertexes constituting each edge of the polygon P ₁ to P _4.

That is, the arithmetic circuit 104 connects, for example, the vertices Q ₁ and Q ₂ forming the edge of the portion where the polygon P ₁ and the polygon P ₄ are adjacent to each other. These vertices Q _1, a line segment L ₁₂ obtained by connecting the Q ₂ is a smooth line segment having a width of one pixel.

Then, the arithmetic circuit 104, the line segment L _12, the frame memory 106 via cache memory 105 as a smooth line segment interpolated by the distance of the nearest two pixel line segment L ₁₂ to the line segment L ₁₂ draw.

The arithmetic circuit 104, for the line segments obtained by connecting the vertices of the other edge, in the same manner as the line segment L ₁₂ obtained by connecting the apexes Q _1, Q _2, as shown in FIG. 4 Then, the image is drawn in the frame memory 106 via the cache memory 105.

As described above, the arithmetic circuit 104 draws a polygon in the frame memory 106 without performing the jaggedness removal processing, and then overwrites a smooth line segment obtained by connecting the vertices constituting the edge of the polygon. The jaggedness of the polygon is removed.

FIG. 5 is a flowchart specifically showing the knurling process of the arithmetic circuit 104. Hereinafter, the jaggedness removal processing of the arithmetic circuit 104 will be specifically described with reference to FIG.

For example, a smooth line segment obtained by connecting the vertices composing the polygon edges are nearly vertical line L _n as shown in FIG. 6, when drawing down the line segment L _n from the top, first, as shown in FIG. 6, the starting point of the line segment L _n and (X1, Y1), to the end point as (X2, Y2). Then, the difference dx at the X coordinate and the difference dy at the Y coordinate between the start point (X1, Y1) and the end point (X2, Y2) are represented by dx
= X2-X1dy = Y2-Y1 (step S1).

Then, the difference dx obtained in step S1, with reference to dy, the slope S of the line segment L _n, determined by S = dx / dy become operational expression (Step S2).

Next, the initial values of the ideal points (Fx, Fy) are set to Fx = X1, Fy = Y1 (step S3).

Next, (Nx, Ny) obtained by converting the ideal point (Fx, Fy) into an integer is represented by Nx = [Fx]
Ny = [Fy]
It is obtained by the following arithmetic expression (step S4).

In the arithmetic expression of step S4, "[]" indicates a Gaussian symbol.

Next, the value of the pixel to be written in (Nx, Ny) obtained in step S4 is obtained, and the obtained pixel value is written in (Nx, Ny) (step S5).

For example, if the pixel value of (Nx−1, Ny) next to (Nx, Ny) is Col1, and the pixel value of the ideal point (Fx, Fy) on the line segment Ln is Col0, (Nx, Ny) The pixel value Col_L to be written in is calculated by the following formula: Col_L = (Fx−Nx) * Col1 + (1−Fx + Nx) * Col0.

Next, the value of the pixel to be written in (Nx + 1, Ny) next to (Nx, Ny) is obtained, and the obtained pixel value is written in (Nx + 1, Ny) (step S6).

For example, if the pixel value of (Nx + 2, Ny) next to (Nx + 1, Ny) is Col2 and the pixel value of the ideal point (Fx, Fy) on the line segment Ln is Col0, write to (Nx + 1, Ny). The pixel value Col_R is obtained by an arithmetic expression of Col_R = (Fx-Nx) * Col0 + (1-Fx + Nx) * Col2.

Next, the next ideal point (Fx, Fy) is calculated as Fx = Fx + (dx / dy)
It is obtained by an arithmetic expression of Fy = Fy + 1 (step S7).

Then, the obtained value of "Fy" in step S7, it is determined whether or not less than the value of the Y coordinate of the end point of the line segment _{L n (X2, Y2) (} = Y2). That is, it is determined whether to exit the writing process of the pixel with respect to the end point of the line segment L _n (X2, Y2) each ideal point to (Fx, Fy) (step S8).

In step S8, if the end point of the line segment L _n (X2, Y2) each ideal point to (Fx, Fy) writing process of pixels to have been determined not to be finished, the process returns to step S4 , And perform the processes of steps S4 to S8.

On the other hand, in step S8, if it is determined the end point of the line segment L _n (X2, Y2) each ideal point to (Fx, Fy) writing process of pixels to have been completed, and terminates the processing of this routine .

As described above, in the arithmetic circuit 104, an ideal point perpendicular to the direction of the line segment Ln (Fx, Fy) closest to 2 pixels (= (Nx, Ny), (Nx + 1, Ny)) and the line segment L _n The drawing is performed at the upper ideal point (Fx, Fy).

Further, the arithmetic circuit 104, two pixels to be drawn in ideal point (Fx, Fy) (= ( Nx, Ny), (Nx + 1, Ny)) is the method of using the two pixels as the direction of the line segment L _n horizontal Or near vertical.

Thus, as a result of removing jaggies processing in the arithmetic circuit 104, the polygon P ₁ to P ₄ shown in FIG. 3, as shown in FIG. 7, each edge of all the polygons P ₁ to P ₄ is smooth The line is overwritten.

That is, the arithmetic circuit 104, the position of each pixel to be drawn in a smooth line segments, because it is drawn using the vertical two pixels in the direction of the line segment, for example, in the polygon P _4, smooth lines the position of an arbitrary pixel D _4n drawn in minutes L _4n is drawn using the two pixels directions perpendicular line segment L _4n d _1, d _2.

As described above, since the drawing apparatus 100 overwrites each edge of all polygons with smooth line segments, the drawing apparatus 100 can easily remove the jaggedness of the entire object composed of polygons. Can be.

Further, in the drawing apparatus 100, after performing the drawing processing without jagged removal, the jagged removal processing shown in the flowchart of FIG. 5 is performed. Can be prevented.

Therefore, the drawing apparatus 100 can perform high-precision drawing without increasing the hardware scale.

In the jaggedness removal processing shown in the flowchart of FIG. 5, the color of each pixel on the smooth line segment to be overwritten may be a common color for the entire line segment, or may be a different color for each pixel. . Accordingly, the above-described jaggedness removal processing can be applied to a line segment on which texture mapping has been performed, and can also be applied to a polygon on which texture mapping has been performed.

In addition, in the jaggedness removal processing shown in the flowchart of FIG. 5, when a smooth line segment is overwritten on the edge of a polygon, a pixel of a line segment that is interpolated with pixels outside the polygon is overwritten with another polygon. In this case, a smooth line segment may be overwritten for each polygon.

Specifically, for example, as shown in FIG. 8, when drawing a two polygons P _5, P _6, since the edge E ₆ of the edge E ₅ and the polygon P ₆ of the polygon P ₅ matches, polygon P portions L ₅₆ consistent with edge E ₅ of the polygon P ₅ smooth line segment L ₆ for _6, is overwritten by the smooth line segment L ₅ for polygon P _5.

In such a case, in the above-described jaggedness removal processing, smooth line segments L ₅ and L ₆ are overwritten for each of the polygons P ₅ and P ₆ . Thereby, the drawing apparatus 100 can prevent the background from bleeding.

In this case, the color of the pixel of the smooth line segment may be interpolated with the color of the pixel of the background. Thus, the drawing apparatus 100 can prevent the background from bleeding when pixels of a smooth line segment to be overwritten on an arbitrary polygon are overwritten by another polygon.

Also, in the jaggedness removal processing shown in the flowchart of FIG. 5, for a pixel completely overwritten by an adjacent polygon, the color of the pixel obtained by mixing the color of the pixel with the color of the background pixel May be written, and smooth line segment overwriting may be performed on pixels other than pixels completely overwritten by adjacent polygons.

Specifically, for example, as shown in FIG. 9, when drawing a two polygons P _7, P _8, since the edge E ₈ of the edge E ₇ and the polygon P ₈ of the polygon P ₇ overlap, the polygon P portions L ₇₈ and duplicate edge E ₇ of the polygon P ₇ a smooth line segment L ₈ for _8, would be completely overwritten by the polygon P _7.

In this case, in the above removing jaggies, for portions L _78, writing the color of the pixels obtained by mixing the color pixels of the color and the background pixel portions L _78, other than the portion L ₇₈ for pixels, to perform the overwriting of smooth line segments L _8. That is, in the above-described jaggedness removal processing, smooth line segments are overwritten only on horizontal edges.

In the jaggedness removal processing shown in the flowchart of FIG. 5, when overwriting a smooth line segment, the color of the line segment and the color of the pixel to be interpolated may be selected as follows.

For example, as shown in FIG. 10, the pixel D (x, y) of the smooth line segment L _n with respect to each weighted by the intersection area of the line segment L _n, the pixel D (x, y) of If the intersection area is “0.5” or more, the pixel is interpolated with the pixel D (x−1, y) adjacent to the pixel D (x, y).

In this way, by selecting pixels to be interpolated according to the weight of the color of the line segment, even if adjacent polygons share the same pixel, they always take different values, so that background bleeding occurs. Can be prevented.

1 is a block diagram illustrating a configuration of a drawing apparatus to which a drawing method according to the present invention is applied. FIG. 7 is a diagram for explaining a state in which edge overlap exists in a polygon to be drawn. It is a figure for explaining a polygon drawn without performing jaggedness removal processing. It is a figure for explaining the state where the vertices which constitute an edge were connected in the above-mentioned jaggedness removal processing. It is a flowchart for demonstrating the said jaggedness removal processing. It is a figure for explaining the case where a near perpendicular line is drawn by the above-mentioned jaggedness removal processing. It is a figure for explaining the state where a polygon was drawn by the above-mentioned jaggedness removal processing. FIG. 14 is a diagram for explaining a jaggedness removal process when a smooth line segment outside a polygon is overwritten by another polygon. FIG. 9 is a diagram for explaining a jaggedness removal process when a smooth line segment inside a polygon is overwritten by another polygon. FIG. 9 is a diagram for explaining a case where a pixel to be interpolated is changed depending on an intersection area. FIG. 3 is a diagram for explaining a three-dimensional shape formed by polygons. It is a figure for explaining the above-mentioned polygon. It is a figure for explaining processing which calculates the maximum value and the minimum value of the Y coordinate of each vertex of the above-mentioned polygon. FIG. 4 is a diagram for describing a process of obtaining an intersection between the polygon and a horizontal pixel line. FIG. 9 is a diagram for explaining a state in which a jagged edge exists as a result of drawing the polygon. FIG. 4 is a diagram for explaining a sub-pixel method for removing the jaggedness. It is a figure for explaining the background mixing method for removing the above-mentioned jaggedness. FIG. 7 is a diagram for explaining a case where jaggedness is removed from two adjacent polygons by the background mixing method.

Explanation of reference numerals

Reference Signs List 100 drawing apparatus, 101 pixel engine, 102 FIFO buffer, 103 cache memory control circuit, 104 arithmetic circuit, 105 cache memory, 106 frame memory

Claims (7)

A drawing method executed by a drawing device that draws an image including polygons on a frame memory based on a drawing command from a CPU,
The drawing device,
A first step of drawing a polygon on a frame memory based on a drawing command from the CPU;
A second step of overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting the vertices of the polygon,
And execute
In the first step, when a plurality of polygons are drawn adjacent to each other and the adjacent polygons are sequentially drawn so as to share vertices, a part of a contour portion of the polygon is a contour of an adjacent polygon. When overlapping with a part, the polygon drawn first is overwritten by the polygon drawn later,
In the second step, a pixel value of a pixel on which the line segment having the predetermined width is drawn is determined based on pixel values of pixels on two polygons adjacent to the pixel, and the determined pixel value is determined. Performing overwriting by the line segment using
Drawing method. The drawing device sets the pixel value of the pixel on which the line segment having the predetermined width is drawn to a pixel value of a pixel adjacent to the pixel and an ideal point on a line segment connecting the vertexes of the polygon. Determined based on the pixel value that was supposed to be allocated,
The drawing method according to claim 1. The drawing device draws the line segment having the predetermined width by using a pixel through which a line segment connecting the vertices of the polygon passes and a pixel adjacent thereto.
The drawing method according to claim 1. The drawing apparatus weights the pixel value of each pixel on the line segment, and selects a pixel value to be interpolated with the pixel value on the line segment according to the weight.
The drawing method according to claim 1. A drawing method executed by a drawing device that draws an image including polygons on a frame memory based on a drawing command from a CPU,
The drawing device,
A first step of drawing a polygon on a frame memory based on a drawing command from the CPU;
A second step of overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting the vertices of the polygon,
And execute
In the first process, when a plurality of polygons are sequentially drawn, when a part of the polygon to be drawn overlaps a part of an adjacent polygon, the polygon is drawn first by a polygon drawn later. While overwriting a part of the polygon,
In the second step, a pixel value of a pixel on which the line segment having the predetermined width is drawn is determined based on pixel values of pixels of two polygons adjacent to the pixel, and the determined pixel value is determined. Performing overwriting by the line segment using
Drawing method. A drawing device that draws an image including a polygon, which is a polygon, on a frame memory based on a drawing command from a CPU,
First means for drawing a polygon on a frame memory based on a drawing command from the CPU;
Second means for overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting the vertices of the polygon,
Equipped with
The first means is that, when the plurality of polygons are sequentially drawn so as to be adjacent to each other and the mutually adjacent ones share vertices, a part of the outline portion of the polygon is adjacent to the outline of the adjacent polygon. When overlapping with a part, the polygon drawn later overwrites the polygon drawn earlier,
The second means determines a pixel value of a pixel on which the line segment having the predetermined width is drawn based on pixel values of pixels on two polygons adjacent to the pixel, and determines the determined pixel value. Is used to overwrite with the line segment,
Drawing device. A drawing device that draws an image including a polygon, which is a polygon, on a frame memory based on a drawing command from a CPU,
First means for drawing a polygon on a frame memory based on a drawing command from the CPU;
Second means for overwriting a contour portion of the drawn polygon with a line segment having a predetermined width connecting the vertices of the polygon,
Equipped with
The first means is configured such that, when a plurality of polygons are sequentially drawn, when a part of a drawn polygon overlaps a part of an adjacent polygon, the polygon is drawn first by a polygon drawn later. While part of the polygon is overwritten,
The second means determines a pixel value of a pixel on which the line segment having the predetermined width is drawn based on pixel values of pixels of two polygons adjacent to the pixel, and determines the determined pixel value. Using the line segment to overwrite,
Drawing device.

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