JP4515877B2 - Outline enhancement drawing device - Google Patents

Description

  The present invention relates to a contour emphasis drawing apparatus that emphasizes primitives constituting a model when three-dimensional computer graphics are displayed.

A conventional contour-enhanced drawing apparatus is implemented for a scan line method in which polygon filling is performed in the scan line direction as disclosed in Japanese Patent Laid-Open No. 4-205484.
This is a method for filling a polygon by creating edges on the left and right sides of the polygon as shown in FIG. 2 and generating pixels between the left and right edges as shown in FIG. By using this edge generation method for contour drawing, the contour of a pixel can be generated.

  As another method of painting, a method of painting in a tiling form is used instead of painting in the scan line direction. This is a method taken in order to perform texture reading efficiently when performing texture mapping. In this method, as shown in FIG. 3, for example, an area on a 2 × 2 tile is considered, and each 2 × 2 pixel is filled while determining whether or not each pixel is inside a primitive triangle. Unlike the scan line method, this method does not include a method for generating an edge. Therefore, when emphasizing an outline, it is necessary to draw using a normal straight line drawing method.

JP-A-4-205484

  Since the conventional tiling method fill method does not generate an edge, it is necessary to perform normal straight line drawing when performing contour emphasis on a painted primitive. Since the method for generating primitive edges by the tiling method and the method for generating primitive edges by the straight line drawing method are different, the same edge is not always generated. In some cases, a contour is generated outside the primitive, or a gap is opened between the contour and the primitive.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and contour-enhanced drawing capable of creating contour enhancement without exceeding the size of the primitive in contour emphasis of the drawing primitive even in the tiling method. Device.

The contour emphasizing drawing device of the present invention is a device for drawing a primitive in 3D graphics by a tiling method, and determines whether or not the center of a pixel including each vertex coordinate of the primitive is inside the primitive. When the pixel is inside, when it is not inside the primitive, the vertex center for straight line is selected to select the adjacent pixel closest to the pixel whose center is inside the primitive and each vertex coordinate of the primitive is included Each pixel selected by the straight line vertex coordinate generation means is used as each vertex data, and a straight line drawing means for drawing a straight line using each vertex data is provided.

  By using the vertex coordinate generation means for straight lines to find the vertex coordinates inside the primitive closest to this vertex data from the vertex data specifying the polygon, the start and end points of the line are inside the primitive. It is possible to draw a straight line inside.

Embodiment 1 FIG.
FIG. 1 is an example of a three-dimensional graphics system used in a personal computer, a PDA (Personal Digital Assistants), or a mobile phone that includes an outline emphasis drawing apparatus according to Embodiment 1 of the present invention. In FIG. 1, a CPU (Central Processing Unit) 11 controls the entire apparatus as a host processor and transfers three-dimensional object data to be drawn to the geometry engine 12. The geometry engine 12 performs coordinate conversion such as rotation, enlargement / reduction, translation, etc. on the drawing primitives such as triangles and straight lines, color calculation by lighting calculation, and clip processing, and renders coordinates and colors in the screen coordinate system to the rendering controller 13. Set to. The rendering controller 13 develops the set drawing primitives such as triangles and straight lines into pixels on the display, and sets the color information in the frame memory 14 and the depth information in the depth memory 15.

In the three-dimensional graphics system configured as shown in FIG. 1, the rendering controller 13 that draws primitives fills the inside of the triangle from the three vertices of the set triangle. When the tiling method is used as the filling method, a minimum rectangular area including a triangle is generated, whether each pixel of this rectangular area exists inside the triangle, and if it is inside, the filling process is performed. If it is outside, the fill process is not performed.
The determination of whether or not the pixel is inside is generally determined by whether or not the center of the pixel is inside the triangle. For example, if there is a triangle shown in FIG. 4, a pixel including vertex 1, vertex 2, and vertex 3 is not drawn because the center of the pixel is not inside the triangle. According to the rule of painting only those whose pixel centers are inside the triangle, the pixels indicated by ◯ in FIG. 4 are painted.

  In order to perform contour emphasis of this primitive, if line drawing is performed using the three vertices of the triangle primitive, pixels including the three vertices are filled, so that a line for contour emphasis is drawn outside the primitive as shown in FIG. . For this reason, the present invention solves this problem by providing the rendering controller 13 with a contour-enhanced straight line drawing device that combines the vertex coordinate generating means for straight lines, the straight line drawing means, and the memory shown in FIG.

  7, 71 is a means for holding the data of the first vertex of the triangle, 72 is a means for holding the data of the second vertex of the triangle, 73 is a means of holding the data of the third vertex of the triangle, 74 is 71, The straight line vertex coordinate generating means for generating straight line drawing vertexes for contour enhancement from the respective vertex data held by 72 and 73 is also used in the calculation unit of the rendering controller 13. 75 is a means for holding the data for the first vertex for straight lines corresponding to the first triangle vertex data holding means 71, and 76 is for holding the data for the second vertex for straight lines corresponding to the second triangle vertex data holding means 72. Means 77 is means for holding the data of the third vertex for straight line corresponding to the triangle third vertex data holding means 73; 78 is a straight line based on the vertex coordinates of each of the vertex data holding means 75, 76 and 77; It is a straight line drawing means for drawing.

  FIG. 8 shows a flow for generating straight-line vertices from the three vertices designated by the triangle primitive. In the first step, the straight line vertex coordinate generation means 74 checks whether or not the center of the pixel in which each vertex coordinate is included is included within the triangle. As a result, if the center of each pixel including each vertex coordinate is inside the triangle, the vertex coordinate generating means 74 for straight line converts each vertex data to the nth vertex for straight line 75, 76, 77 in FIG. Transfer to data holding means. If the center of each pixel including each vertex coordinate is not inside the triangle, the vertex coordinate generator 74 for straight lines selects the surrounding 8 pixels surrounding the pixel including this vertex coordinate in step 2. Next, in step 3, the straight vertex coordinate generating means 74 selects the pixel within the triangle from the selected 8 pixels and having the shortest distance between the vertex pixel and the center of the selected pixel. In step 4, the pixel selected in step 3 is copied to the data holding means for the nth vertex for straight lines 75, 76 and 77 in FIG.

  In the straight line vertex coordinate generation means 74, each vertex data for straight lines is generated according to the flow of FIG. 8, stored in the holding means, and then the straight line drawing means 78 draws a straight line using each vertex data. By doing so, since each vertex of the straight line is inside the triangle as shown in FIG. 6, it is possible to draw a straight line inside the triangle primitive.

  The calculation by the straight vertex coordinate generation means 74 can be performed by the calculation unit of the geometry engine 12 of FIG. 1 in addition to the calculation by the calculation unit of the rendering controller 13 of FIG.

  Further, the calculation of the straight vertex coordinate generation means 74 can be performed by the CPU 11 of FIG.

Embodiment 2. FIG.
FIG. 9 shows an outline-enhanced straight line drawing apparatus according to Embodiment 2 of the present invention. In the second embodiment, depth offset means is added to the contour-enhanced straight line drawing apparatus of the first embodiment shown in FIG. The depth offset unit 98 performs an offset process on the Z value that is the depth component of the straight line coordinate generated by the straight line vertex coordinate generation unit 74. In general, the Z value increases as the front is zero and the depth increases. For this reason, the depth offset means 98 shifts to the front by the offset value. As a result, the Z value conflict caused by the difference in the Z value generation method between the polygon and the straight line can avoid the situation where the straight line is drawn like a dotted line on the polygon and is not drawn cleanly. The outline can be drawn.

Embodiment 3 FIG.
In the third embodiment, the straight line drawing means 78 in the first embodiment is provided with a determination means and a correction means. Each time a pixel is generated by the straight line drawing means 78, the relation between the pixel and the triangle primitive is checked by the determining means. If the center of the generated pixel is not inside the triangle primitive, the same scan line is used for the adjacent pixels. The correction means replaces the pixel whose upper center is located inside the triangle primitive.

This is because the pixels other than the start point and end point of the line are outside the triangle primitive due to the difference between the triangle rasterization method and the line rasterization method , even though the start point and end point are pixels inside the triangle primitive as shown in FIG. This is to avoid getting out. That is, as shown in FIG. 10, the pixels generated by the triangle rasterizing method are the pixels on the left outermost black side on the same scan line in FIG. 10 by the straight lines forming the triangle primitives. The pixel generated by the above is a pixel generated based on the straight line drawn by the straight line drawing means 78, and is a blackened pixel located one right of the pixel. In this embodiment, all the pixels generated by the triangle rasterization method are not located inside the triangle primitive, and pixels generated by the straight line rasterization method may or may not be located inside the triangle primitive. is there.

A processing flow for this is shown in FIG. In step 1, the pixel generated by the straight line drawing unit 78 is determined by the determining unit whether the center is inside the triangle primitive. As a result, if it is inside the triangle primitive, the pixel is drawn in step 3. If it is determined that it is not inside the triangle primitive, the pixel whose center is inside the triangle primitive among the adjacent pixels on the same scan line in step 2 is selected by the correcting means, and the pixel is drawn in step 3.
In this way, all pixels other than the start point and the end point can be included in the triangle primitive.

  It can be applied to 3D graphics systems mounted on personal computers, mobile phones, mobile terminals, etc., and the mounted devices can be enhanced in functionality and functionality.

1 is a configuration diagram of a three-dimensional graphics system including an outline emphasis drawing device according to Embodiment 1 of the present invention. It is explanatory drawing of the polygon filling method by a scan line system. It is explanatory drawing of the polygon filling method by a tiling system. It is explanatory drawing of the pixel filling method of the triangle primitive by this invention. It is explanatory drawing of the straight line drawing method by three vertices of a triangle primitive. It is explanatory drawing of the straight line drawing method of the triangle primitive by this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the outline emphasis straight line drawing apparatus in Embodiment 1 of this invention. It is a flowchart which produces | generates the vertex for straight lines from the triangle primitive 3 vertex. It is a block diagram of the outline emphasis straight line drawing apparatus of Embodiment 2 by this invention. It is explanatory drawing in which pixels other than the starting point and the end point of a straight line become outside a triangle. FIG. 11 is an operation flowchart of straight line drawing means in the third embodiment.

Explanation of symbols

  11 CPU, 12 Geometry engine, 13 Rendering controller, 14 Frame memory, 15 Depth memory, 71 Triangle first vertex data holding means, 72 Triangle second vertex data holding means, 73 Triangle third vertex data holding means, 74 Straight line vertex Coordinate generating means, 75 straight first vertex data holding means, 76 straight second vertex data holding means, 77 straight third vertex data holding means, 78 straight line drawing means, 98 depth offset means.

Claims (2)

In a device that draws primitives in 3D graphics using the tiling method, it is determined whether or not the center of the pixel including each vertex coordinate of the primitive is inside the primitive. When not inside the primitive, the vertex coordinates generating means for straight line selecting the adjacent pixel closest to the pixel whose center is inside the primitive and each vertex coordinate of the primitive is included, and generating the vertex coordinates for the line An outline-enhanced drawing apparatus including straight line drawing means for setting each pixel selected by the means as each vertex data and drawing a straight line using each vertex data . The primitive has a triangular shape, and the straight line drawing means determines whether or not the center of each pixel generated based on the straight line drawn by the straight line drawing means is located inside the triangle primitive; 2. The contour emphasizing drawing apparatus according to claim 1, further comprising means for correcting the pixel to an adjacent pixel whose center is located within the triangle primitive when the center of the pixel is not located within the triangle primitive .

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