JP3872056B2 - Drawing method - Google Patents

Description

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

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

  That is, when generating a three-dimensional image with the image generating apparatus, the CPU does not directly access the frame buffer, but performs geometric processing such as coordinate conversion, clipping, and light source calculation, and performs various processes such as triangles and quadrangles. A three-dimensional shape is defined as a combination of polygons (polygons), a drawing command for drawing a three-dimensional image is generated, and the drawing command is transferred to the drawing device.

Specifically, for example, when generating an image of a three-dimensional object 200 as shown in FIG. 11, first, the CPU defines the object 200 as a combination of polygons P _201, P ₂₀₂ , and P ₂₀₃ .

Then, the CPU generates a drawing command 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 command to the drawing device.

  The drawing apparatus interprets the drawing command transferred from the CPU, and considers the color and Z value of all the pixels constituting the polygon from the vertex color data and the Z value indicating the depth, and stores the pixel data in the frame buffer. A rendering process is performed to write to the frame buffer, and a figure is drawn in the frame buffer.

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

That is, for example, when drawing the polygon P ₂₀₁ shown in FIG. 12 among the polygons P ₂₀₁ , P ₂₀₂ and P ₂₀₃ constituting the object 200, the drawing apparatus first interprets the drawing command from the CPU, thereby 13, Y coordinates y ₁ , y of the four vertices (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), (x ₄ , y ₄ ) of the polygon P _{201 2} , y ₃ , 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 lattice pattern, but the four vertices (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ ) of the polygon P ₂₀₁ are arranged. , Y ₃ ), (x ₄ , y ₄ ) do not necessarily match the lattice 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 to obtain horizontal pixel lines L _{H2 to} L _H17 that intersect with the polygon P _201. . Then, the drawing apparatus obtains intersections between the polygon P ₂₀₁ and the horizontal pixel lines L _{H2 to} L _H17 .

Next, the drawing apparatus performs a value truncation process on the value of the X coordinate of the intersection, and obtains the maximum value X _max and the minimum value X _min of the X coordinate of the pixel included in the polygon P ₂₀₁ .

Then, the drawing apparatus writes, in the horizontal pixel lines L _{H2 to} L _H17 , pixels included in the range of the X coordinate minimum value X _min to the maximum value X _max in 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, the boundary (edge) E of the polygon P ₂₀₁ is in a jagged state (hereinafter referred to as jagged) as shown in FIG. Say.)

  Therefore, in the above drawing apparatus, for example, a subpixel method, a background mixing method, or the like has been adopted as a method for removing the roughness.

  The sub-pixel method is a method for removing a roughness by drawing a polygon in a frame buffer at a higher resolution than the actual display resolution and finally applying a low-pass filter to lower the actual display resolution.

Specifically, first, FIG. 16A shows the frame buffer of the polygon P ₂₀₁ shown in FIG. 12 at a resolution twice as high as the display resolution in each of the horizontal (H) direction and the vertical (V) direction. It is the figure which showed the state drawn in. That is, one pixel (pixel) D _n of the frame buffer corresponds to 2 × 2 sub-pixels SD _{n1 to} SD _n4 . Therefore, the subpixels SD _{n1 to} SD _n4 include a plurality of colors. Therefore, for each pixel, an average value of a plurality of colors included in the subpixels SD _{n1 to} SD _n4 is obtained, and the average value is set as the color of the display pixel.

For example, as shown in FIG. 16A, when each color of the background B and the polygon P ₂₀₁ is one color, the average value of the plurality of colors included in the sub-pixels SD _{n1 to} SD _n4 is 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 P ₂₀₁ is drawn in the frame buffer by display pixels having five levels of colors.

  However, in the conventional drawing apparatus adopting the subpixel method as described above, it is necessary to perform drawing at a resolution higher than the actual display resolution, so it is necessary to provide a frame buffer having a resolution higher than the actual display resolution. . As a result, the hardware scale of the drawing apparatus has increased.

  On the other hand, in the background mixing method, when the true edge of a polygon intersects with a pixel, the ratio of the polygon's interior to the pixel is calculated, and the polygon color and background color are mixed at that ratio. This is a method for removing the gap.

Specifically, FIG. 17 is a diagram showing a state where the polygon P ₂₀₁ shown in FIG. 12 is drawn in the frame buffer after removing the gap by the background mixing method.

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 at the edge E1 of the polygon P ₂₀₁ is “green blue”. It becomes.

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 is “green red”, and the polygon P ₂₀₂ The color of the pixel of the edge E ₁₂ shared by ₂₀₁ and the polygon P ₂₀₂ is “green blue red” obtained by adding “red” to the color “green blue” of the pixel of the edge E 1.

Here, since the background B should not be visible at the edge E ₁₂ shared by the polygon P ₂₀₁ and the polygon P ₂₀₂ , the pixel color of the edge E ₁₂ should be “blue-red”. In addition, the color of the pixel at the edge E12 is “green blue red”, and the color of the background B appears.

  That is, in the conventional drawing apparatus employing the background mixing method as described above, the background color is blurred by being mixed with the edge color up to the background color that should not be seen.

  Accordingly, the present invention has been made in view of the above-described conventional situation 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 problems, 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, and is drawn in the frame memory. A line segment connecting vertices corresponding to the polygon outline portion is overwritten on the polygon outline portion.
For example, the drawing method of the present invention is a drawing method executed by a drawing device that draws an image including a polygon that is a polygon on a frame memory based on a drawing command from a CPU, and the drawing device includes: Based on the drawing command from the CPU, the first process of drawing the polygon on the frame memory and the line segment of the predetermined width connecting the vertices of the polygon are overwritten on the drawn outline of the polygon. In the first process, the polygons are drawn in order so that a plurality of the polygons are adjacent to each other, and those adjacent to each other share a vertex. When a part of the outline part of the polygon overlaps with the outline part of the adjacent polygon, the polygon drawn earlier is overwritten by the polygon drawn later. In the second process, the pixel value of the pixel on which the line segment of the predetermined width is drawn is determined based on the pixel value of the pixel on the two polygons adjacent to the pixel, and the determined value It is assumed that overwriting with the line segment is performed using a pixel value.
Alternatively, a drawing method executed by a drawing device that draws an image including a polygon that is a polygon on a frame memory based on a drawing command from the CPU, wherein the drawing device is based on the drawing command from the CPU. A first process of drawing a polygon on the frame memory, a second process of overwriting a line segment of a predetermined width connecting the vertices of the polygon with respect to the drawn outline portion of the polygon, In the first process, when a plurality of polygons are drawn in order in the first step, when a part of the drawn polygon overlaps with a part of the adjacent polygon, the polygon drawn later In the second process, the pixel value of the pixel on which the line segment having the predetermined width is drawn is changed to be overwritten. 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.
The drawing device of the present invention is 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, for example, and is based on the drawing command from the CPU. A first means for drawing a polygon on a frame memory; and a second means for overwriting a line segment having a predetermined width connecting the vertices of the polygon with respect to the contour portion of the drawn polygon. In the case where a plurality of the polygons are adjacent to each other and are drawn in order so that the adjacent polygons share a vertex, the first means includes the polygons whose contour portions are adjacent to each other. In the case where it overlaps with the contour portion, the polygon drawn earlier is overwritten by the polygon drawn later, and the second means 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. It can be assumed to be overwritten.
Alternatively, the drawing apparatus draws an image including a polygon, which is a polygon, on the frame memory based on a drawing command from the PU, and draws the polygon on the frame memory based on the drawing command from the CPU. First means and second means for overwriting a line segment having a predetermined width connecting the vertices of the polygons with respect to the contour portion of the drawn polygons. In the case where a plurality of polygons are drawn in order and a part of the drawn polygon overlaps with a part of the adjacent polygon, a part of the polygon drawn earlier by the polygon drawn later is 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 two polygon pixels adjacent to the pixel, and determines the determined pixel value. It is also possible to use the above-mentioned line segment for overwriting.
Since these perform the removal process after performing the drawing process without the removal of the gap, it is possible to prevent the appearance of a color that should not be visible such as the background color.

  The drawing apparatus sets the pixel value of the pixel on which the line segment of the predetermined width is drawn to an ideal point on the line segment connecting the pixel value of a pixel adjacent to the pixel and the vertices of the polygon. It may be determined based on the pixel value that should have been arranged.

  In the drawing method, the line segment having the predetermined width may be drawn by a pixel through which a line segment connecting the vertices of the polygon passes 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 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 segment connecting the vertices corresponding to the polygonal outline part is overwritten on the polygonal outline part drawn in the frame memory. As a result, the drawing method can easily remove the entire object composed of polygons, and can prevent the appearance of colors that should not be visible, such as the background color. Therefore, the drawing method can perform high-precision drawing with small-scale hardware.

  In the drawing method according to the present invention, the line segment is overwritten on the contour portion using a pixel value adjacent to the contour portion. Thereby, the drawing method can prevent background blur. Therefore, the drawing method can perform drawing with higher accuracy.

  In the drawing method according to the present invention, the pixel value obtained by mixing the pixel value of the background with the pixel value of the contour portion is overwritten on the contour portion overlapped by the adjacent polygon. As a result, the drawing method can remove the entire object composed of polygons even when pixels that are completely overwritten by adjacent polygons are generated. Therefore, the drawing method can perform drawing with higher accuracy.

  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 drawing method, even when adjacent polygons share the same pixel, different values are always taken. Therefore, since the drawing method can prevent background blurring, drawing with higher accuracy can be performed.

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

  The drawing method according to the present invention is implemented 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 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.

  For example, a drawing command from a CPU (not shown) is supplied to the pixel engine 101. 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 graphics (polygons) such as triangles and quadrangles 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. The arithmetic circuit 104 performs Z buffer processing, translucent processing, anti-aliasing processing, filtering processing, and the like when writing pixel data to the frame memory 106 via the cache memory 105.

  Further, the arithmetic circuit 104 reads out pixel data from the frame memory 106 via the cache memory 105, and performs a removal process on the read out 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 reads in advance the pixel data once stored in the FIFO memory 102, thereby recognizing in advance a data area required in the cache memory 105. Then, the cache memory control circuit 103 reads the pixel data corresponding to the data area from the frame memory 106 without crossing the word boundary and page boundary of the frame memory 106, and also corresponds to the data area. The cache memory 105 is controlled so that the pixel data is collectively written in the frame memory 106. As a result, the cache memory 105 accesses the frame memory 106 by shortening the access time, and performs access to the frame memory 106 with a small number of times.

  Although not shown, the frame memory 106 includes a Z buffer and a frame buffer. 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 based on 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 stored in the frame memory 106. The data is output to the arithmetic circuit 104 via the cache memory 105.

  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, or the like (not shown).

  As a result, 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 grind removal process performed by the arithmetic circuit 104 will be specifically described.

For example, when a three-dimensional model composed of _four polygons P _{1 to} P ₄ as shown in FIG. 2 is drawn in the frame memory 106, first, the arithmetic circuit 104 performs polygon P ₁ to P ₄ is drawn in the frame memory 106 via the 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 Are overlapped, and the edge E ₂₃ shared by the polygon P ₂ and the polygon P ₃ is a state in which the pixel of the edge of the polygon P ₂ and the pixel of the edge of the polygon P ₃ are adjacent without overlapping. That is, at the edge sharing the vertexes of the polygons, the polygons are arranged without gaps.

Therefore, when the polygons are 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. 3, the polygons are drawn later on the edges sharing the vertices of the polygons. Polygon pixels are written.

Next, the arithmetic circuit 104 connects the vertices constituting the edges of the polygons P _{1 to} P ₄ to the polygons P _{1 to} P ₄ drawn in the frame memory 106 without performing the removal processing.

That is, the arithmetic circuit 104 connects, for example, the vertices Q ₁ and Q ₂ constituting the edge of the portion where the polygon P ₁ and the polygon P ₄ are adjacent to each other. A line segment L ₁₂ obtained by connecting these vertices Q ₁ and 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.

Further, the arithmetic circuit 104 makes the line segment obtained by connecting the vertices constituting other edges the same as the line segment L ₁₂ obtained by connecting the vertices Q ₁ and Q ₂ as shown in FIG. 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 removal process, and then overwrites a smooth line segment obtained by connecting the vertices constituting the edge of the polygon, The above-mentioned polygonal burrs are removed.

  FIG. 5 is a flowchart specifically showing the jagged removal processing of the arithmetic circuit 104. Hereinafter, with reference to FIG. 5 described above, the grind removal processing of the arithmetic circuit 104 will be specifically described.

For example, when a smooth line segment obtained by connecting the vertices constituting the edge of a polygon is a line segment L _n close to the vertical as shown in FIG. 6 and the line segment L _n is drawn from the top to the bottom, 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 in the X coordinate between the start point (X1, Y1) and the end point (X2, Y2) and the difference dy in the Y coordinate are expressed as dx.
= X2−X1dy = Y2−Y1 is obtained by an arithmetic expression (step S1).

Next, using the difference dx, dy obtained in step S1, the slope S of the line segment L _n is obtained by an arithmetic expression of S = dx / dy (step S2).

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

Next, the ideal point (Fx, Fy) is converted into an integer (Nx, Ny), and Nx = [Fx]
Ny = [Fy]
It calculates | requires by the computing equation which becomes (step S4).

  In the arithmetic expression in step S4, “[]” indicates a Gaussian symbol.

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

  For example, when 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 to is obtained by the following equation: Col_L = (Fx−Nx) * Col1 + (1−Fx + Nx) * Col0.

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

  For example, when 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, the pixel value is written to (Nx + 1, Ny). The pixel value Col_R is obtained by the following equation: Col_R = (Fx−Nx) * Col0 + (1−Fx + Nx) * Col2.

Next, the next ideal point (Fx, Fy) is expressed as Fx = Fx + (dx / dy)
Fy = Fy + 1 is obtained by an arithmetic expression (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 Each process of step S4 to step S8 is performed.

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 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 It is determined depending on whether it is close to or vertical.

Therefore, as a result of the removal processing performed by the arithmetic circuit 104, the polygons P _{1 to} P ₄ shown in FIG. 3 have smooth edges at all the polygons P _{1 to} P ₄ as shown in FIG. The line is overwritten by the line segment.

That is, since the arithmetic circuit 104 draws two pixels perpendicular to the direction of the line segment at the position of each pixel drawn by the smooth line segment, for example, a smooth line in the polygon P ₄ 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, in the drawing apparatus 100, each edge of all polygons is overwritten with a smooth line segment. Therefore, the drawing apparatus 100 can easily remove the entire object composed of polygons. Can do.

  Further, since the rendering apparatus 100 performs the removal process shown in the flowchart of FIG. 5 after performing the rendering process without the removal of the roughness, the rendering apparatus 100 displays the appearance of a color that should not be visible such as the background color. Can be prevented.

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

  Note that in the greaking removal process 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 the line segment on which texture mapping has been performed, and can also be applied to the polygon on which texture mapping has been performed.

  In addition, in the removal processing shown in the flowchart of FIG. 5, when a smooth line segment is overwritten on the edge of the polygon, the pixel of the line segment interpolated with the pixel outside the polygon is overwritten by another polygon. In this case, smooth line segments 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 _The portion L ₅₆ that coincides with the edge E ₅ of the polygon P ₅ of the smooth line segment L ₆ for ₆ is overwritten by the smooth line segment L ₅ for the polygon P ₅ .

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

  In this case, the pixel color of the smooth line segment may be interpolated with the color of the background pixel. As a result, the drawing apparatus 100 can prevent blurring of the background when a pixel of a smooth line segment to be overwritten on an arbitrary polygon is overwritten with another polygon.

  In addition, in the removal processing shown in the flowchart of FIG. 5 above, for the pixel that is completely overwritten by the adjacent polygon, the color of the pixel obtained by mixing the color of the pixel and the color of the background pixel. And a smooth line segment may be overwritten on pixels other than those 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 to say, in the above-described jaggedness removal processing, smooth line segments are overwritten only on horizontal edges.

  Further, when the smooth line segment is overwritten in the jagged removal process shown in the flowchart of FIG. 5, 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, each pixel D (x, y) on the smooth line segment L _n is weighted by the intersection area of the line segment L _n , and the pixel D (x, y) When the crossing area is “0.5” or more, it 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 color weight of the line segment, even if adjacent polygons share the same pixel, it always takes different values, so background blurring Can be prevented.

It is a block diagram which shows the structure of the drawing apparatus to which the drawing method which concerns on this invention is applied. It is a figure for demonstrating the state where edge duplication existed in the polygon which is going to draw. It is a figure for demonstrating the polygon drawn without performing a burrow removal process. It is a figure for demonstrating the state which tied the vertex which comprises an edge in the said removal processing. It is a flowchart for demonstrating the said removal process. It is a figure for demonstrating the case where a line segment near perpendicular | vertical is drawn by the said removal process. It is a figure for demonstrating the state by which the polygon was drawn by the said clearance removal process. It is a figure for demonstrating the jaggedness removal process in case the smooth line segment outside a polygon is overwritten by another polygon. It is a figure for demonstrating the jaggedness removal process in case the smooth line segment inside a polygon is overwritten by another polygon. It is a figure for demonstrating the case where the pixel to interpolate is changed with an intersection area. It is a figure for demonstrating the three-dimensional shape comprised from a polygon. It is a figure for demonstrating the said polygon. It is a figure for demonstrating the process which calculates | requires the maximum value and minimum value of the Y coordinate of each vertex of the said polygon. It is a figure for demonstrating the process which calculates | requires the intersection of the said polygon and a horizontal pixel line. It is a figure for demonstrating the state where a jaggedness exists as a result of drawing the said polygon. It is a figure for demonstrating the subpixel method for removing the said roughness. It is a figure for demonstrating the background mixing method for removing the said roughness. It is a figure for demonstrating the case where the removal of a gap is performed with respect to two adjacent polygons by the said background mixing method.

Explanation of symbols

100 drawing device, 101 pixel engine, 102 FIFO buffer, 103 cache memory control circuit, 104 arithmetic circuit, 105 cache memory, 106 frame memory

Claims (8)

A drawing method executed by a drawing apparatus that draws an image including a polygon that is a polygon on a frame memory based on a drawing command from a CPU,
The drawing device is
A first process of drawing a polygon on a frame memory based on a drawing command from the CPU;
A second step of overwriting a line segment having a predetermined width connecting the vertices of the polygon with respect to the drawn outline portion of the polygon;
Is to execute
In the first process, when a plurality of polygons are adjacent to each other and are drawn in order so that those adjacent to each other share a vertex, a part of the polygon outline part is adjacent to the polygon outline When it overlaps with the part, the polygon drawn earlier 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 Overwrite with the line segment using
Drawing method. The drawing apparatus sets the pixel value of the pixel on which the line segment of the predetermined width is drawn to an ideal point on the line segment connecting the pixel value of a pixel adjacent to the pixel and the vertices of the polygon. Decide based on the pixel values that should have been placed,
The drawing method according to claim 1. The drawing apparatus draws the line segment having the predetermined width by 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 device weights the pixel value of each pixel on the line segment, and selects a pixel 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 apparatus that draws an image including a polygon that is a polygon on a frame memory based on a drawing command from a CPU,
The drawing device is
A first process of drawing a polygon on a frame memory based on a drawing command from the CPU;
A second step of overwriting a line segment having a predetermined width connecting the vertices of the polygon with respect to the drawn outline portion of the polygon;
Is to execute
In the first step, when 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, a part of the drawn polygon is a part of the adjacent polygon Draw at least two of the polygons so that they line up without any gaps ,
In the second step, the pixel value of the pixel on which the line segment having the predetermined width is drawn, which is located in an adjacent portion of the two polygons arranged without gaps , is set to two adjacent pixels. It is determined based on the pixel value of the pixel of the polygon, and overwriting with the line segment is performed using the determined pixel value.
Drawing method. 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 CPU,
A first means for drawing a polygon on a frame memory based on a drawing command from the CPU;
A second means for overwriting a line segment of a predetermined width connecting the vertices of the polygon with respect to the drawn outline portion of the polygon;
With
In the case where a plurality of the polygons are adjacent to each other and the adjacent ones are drawn in order so that the adjacent ones share a vertex, the first means includes a polygon outline in which a part of the polygon outline part is adjacent. When it overlaps with the part, the polygon drawn earlier is overwritten by the polygon drawn later,
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 the determined pixel value Overwrite with the line segment using
Drawing device. 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 CPU,
A first means for drawing a polygon on a frame memory based on a drawing command from the CPU;
A second means for overwriting a line segment of a predetermined width connecting the vertices of the polygon with respect to the drawn outline portion of the polygon;
With
The first means is that when a plurality of the polygons are adjacent to each other and the adjacent polygons are sequentially drawn so that they share a vertex, a part of the polygon to be drawn is a part of the adjacent polygon And draw at least two of the polygons so that they line up without any gaps ,
The second means calculates a pixel value of a pixel on which the line segment having the predetermined width , which is located in an adjacent portion of the two polygons arranged without gaps , is adjacent to the pixel. It is determined based on the pixel value of the pixel of the polygon, and the line segment is overwritten using the determined pixel value.
Drawing device. The drawing device weights the pixel value of each pixel on the line segment, and selects a pixel to be interpolated with the pixel value on the line segment according to the weight.
The drawing method according to claim 5.

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