JPH0567218A - Pixel coordinate computer and image forming device using the same - Google Patents

Abstract

PURPOSE:To provide an image forming device which solves a problem that a pixel coordinate calculation is inefficient in the case of a small polygon and which can realize a high speed processing. CONSTITUTION:A polygon selector 1 selects the small polygon capable of calculating the pixel coordinate in a first pixel coordinate computer 5 among the plural plotted polygons. The first pixel coordinate computer 5 consisting of a vertex coordinate converter 2, a pixel coordinate table 3 and a pixel coordinate converter 4 finds the pixel coordinate of the selected polygon, and a second pixel coordinate computer 6 as to the polygon which is not selected. A pixel data computing element 7 calculates the colors and luminance of the respective picture elements based on the coordinates, and the operated result is stored in a frame memory 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to calculation of pixel coordinates in computer graphics and an image generating apparatus using the same.

[0002]

2. Description of the Related Art In recent years, with the development of computer graphic technology, complex image processing has become possible. At times, many inventions have been made to improve the processing accuracy and processing speed. Conventional computer of this kind
When calculating the pixel coordinates of the inside and edges of a polygonal image given the vertex coordinates by graphic technology, the intersections of a straight line parallel to the X axis called a scan line and the edge are obtained, and these intersections are set. We have taken the method of finding the pixels on the enclosed scan line. These processing methods are described in detail, for example, in "Computer Graphics", translated by Atsumi Imamiya, Japan Computer Association (1984). Less than,
An example of the conventional pixel coordinate calculation will be described with reference to FIGS. 4 and 5.

FIG. 4 shows a configuration example of a conventional pixel coordinate calculation device. As shown in FIG. 4, the component 41 is an edge inclination calculator, which calculates the inclination of each edge from the coordinates of each vertex of the polygon. 42 is a pixel coordinate calculator on the edge, which calculates the pixel coordinate on the edge from each vertex of the polygon and the inclination of the edge. Reference numeral 43 denotes a pixel coordinate calculator inside the polygon, which calculates the pixel coordinates inside the polygon from the pixel coordinates on the edge. As an example, FIG. 5 shows a method for obtaining the internal pixel and the pixel coordinate on the edge from the vertex coordinates of the triangle.

First, the edge inclination calculator 41 is used to calculate the vertex 51.
The inclination of the edge 54 based on the coordinates of and the coordinates of the vertex 52, and the inclination of the edge 55 from the coordinates of the vertex 52 and the coordinates of the vertex 53
The inclination of the edge 56 is obtained from the coordinates of the vertex 53 and the coordinates of the vertex 51. An edge pixel coordinate calculator 42 obtains pixel coordinates on the edge 54 from the coordinates of the vertex 51 and the inclination of the edge 54, and pixel coordinates on the edge 56 from the coordinates of the vertex 51 and the inclination of the edge 56. The pixel coordinates on the edge 55 are obtained from the coordinates of the vertex 52 and the inclination of the edge 55.

Next, in the internal pixel coordinate calculator 43,
Pixel coordinates on a line segment that joins two points on the edge with the same y coordinate value are calculated. This line segment is called a scan line. The scan line 57 represents one of a plurality of scan lines that exist. Pixel 58 and pixel 59 are the intersections of scan line 57 and edge 54 and edge 56, respectively. Pixel 60 and pixel 61 are both scan line 5
It is a pixel on 7 and is a pixel inside a triangle. Pixel 5
From 8 and pixel 59, the coordinates of pixel 60 and pixel 61 are obtained. By performing this process for all scan lines, the pixel coordinates inside the triangle are obtained.

[0006]

However, in the above-mentioned structure, it takes a lot of multiplication and division operations to obtain the pixel coordinates on the edge regardless of the size of the polygon, so that the calculation is time-consuming, and especially for small polygons. In the case of (2), although the number of pixel coordinates to be obtained is small, a great amount of calculation time is spent, and there is a problem that efficiency is low.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image generation apparatus capable of efficiently calculating pixel coordinates on edges and inside polygons even for small polygons.

[0008]

In order to achieve the above object, a pixel coordinate calculating apparatus and an image processing apparatus using the same according to the present invention select one point from the vertices of a polygon as a reference point, and use this reference point. From the vertex coordinate converter that converts the vertex coordinates other than points to the relative coordinates from the reference point, and the relative pixel coordinates from the reference points that form the inside and edges of the polygon from the relative vertex coordinates output by this vertex coordinate converter. The pixel coordinate table for obtaining the pixel coordinate table and the pixel coordinate converter for converting the relative pixel coordinates into the absolute pixel coordinates are provided.

[0009]

The pixel coordinate calculation apparatus of the present invention having the above-described configuration and the image generation apparatus using the same are configured to calculate the pixel coordinates when drawing a small polygon, in order to obtain the vertex coordinates of the polygon and the edges and the internal pixel coordinates. By referring to the pixel coordinate table in which the correspondence is described, it is not necessary to perform calculations such as edge tilt and pixel coordinate calculation on the edge.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Calculation of pixel coordinates of a triangle according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an image generating apparatus according to an embodiment of the present invention. As shown in FIG. 1, as its constituent elements, 1 is a polygon selector for selecting the size of polygons, 2 is a vertex coordinate converter for converting one of the vertex coordinates into a relative coordinate, and 3 is a relative pixel coordinate. Pixel coordinate table, which is a correspondence table of edges and pixels inside the polygon, 4 is a pixel coordinate converter for converting relative pixel coordinates into absolute pixel coordinates, 5 is a first pixel coordinate calculation device, and 6 is a second pixel coordinate calculation. A device, 7 is a pixel data calculator for calculating the color and brightness of a pixel, and 8 is a frame memory. The operation of the image generating apparatus configured as described above will be described below.

First, the overall processing flow will be described. The polygon selector 1 selects a small polygon for which the pixel coordinate calculation can be performed by the first pixel coordinate calculation device from a plurality of polygons to be drawn. The vertex coordinate values of the polygons selected by the polygon selector 1 are input to the first pixel coordinate calculation device 5, and the vertex coordinate values of the unselected polygons are input to the second pixel coordinate calculation device 6. It The second pixel coordinate calculation device 6 is a device for calculating pixel coordinates by a conventional method. The pixel coordinate value output from the first pixel coordinate calculation device 5 or the second pixel coordinate calculation device 6 is input to the pixel data calculator 7 to calculate the color and brightness of each pixel, and the calculation result is stored in the frame memory. Store in 8.

Next, the first pixel coordinate calculation device 5 will be described. The first pixel coordinate calculation device 5 includes the vertex coordinate converter 2
And a pixel coordinate table 3 and a pixel coordinate converter 4. The vertex coordinate converter 2 selects one point from the vertex coordinates of the polygon as a reference point, and converts the other vertex coordinates into relative coordinates from the reference point. The pixel coordinate table 3 looks up the table from the coordinate values output by the vertex coordinate converter 2 to find the pixel coordinates of the polygon. Since the pixel coordinates obtained in the pixel coordinate table 3 are relative coordinates from the reference point, the pixel coordinate converter 4 converts the relative pixel coordinates into absolute pixel coordinates. FIG. 2 shows a pixel coordinate calculation process using concrete coordinate values of a triangle.
Shown in. In FIG. 2A, reference numeral 21 indicates the absolute vertex coordinates of the drawn triangle. If (2,3), which is one of the three coordinates, is selected as the reference point by the vertex coordinate converter 2,
The other vertex coordinates (6, 4) and (5, 6) are respectively shown in FIG.
Are converted into relative vertex coordinates (4,1) and (3,3) of the 22 triangles shown in FIG. Based on the relative vertex coordinates 22 of this triangle, the relative pixel coordinates (1,0), (0,1) of the inside and the edge of the triangle of the pixel coordinate tables 23 to 24 shown in FIG.
(2,1), (2,2), (3,1), (3,2) are obtained. This relative pixel coordinate 24 is calculated by the pixel coordinate converter 4 as shown in FIG.
25 absolute pixel coordinates (3.3), (2, 4) shown in (d),
Converted to (4,4), (4,5), (5,4), (5,5), respectively. In FIG. 2, the case where the pixel coordinates of the triangle are obtained has been described as an example, but the pixel coordinates are calculated in the same manner for polygons other than the triangle.

Next, a polygon selecting method in the polygon selector 1 will be described. In the polygon selector 1, one of the vertices of the polygon is selected as a reference point, and the polygons are classified according to whether or not the displacements of the reference point and the coordinates of any other vertices in x and y coordinates are both m or less. To do. m is a constant of a natural number. An example in the case of m = 3 is shown in FIG. In FIG. 3, ⊚ mark 31 represents a reference point, plural ∘ marks 32 represent pixels whose displacements in x and y coordinates from the reference point are all 3 or less, and 33 and 34 are selected by the polygon selector 1. Polygons are shown, and 35 is a polygon that is not selected by the polygon selector 1. That is, one vertex of the polygon is the reference point 3
When 1 is set, if any of the other vertices is any one of the pixels 32 indicated by a circle, the polygon is selected by the polygon selector 1.

The value of m is related to the size of the pixel coordinate table. For example, consider the size of the pixel coordinate table 3 when m = 3 is determined in the case of handling only triangles. In the case of a triangle having two vertices of the reference point and other pixels as the apex, the number is a combination in which two are selected from the 48 pixels 32, and therefore there are 1128 patterns including the case of a straight line.

[0015]

[Equation 1]

A value obtained by subtracting the number when three points are arranged on a straight line from this value corresponds to the number of entries of the pixel coordinate conversion table 3. Therefore, the number of entries is less than 1128.
Next, since the largest triangle has 15 pixels (excluding the reference point) forming one triangle, it is sufficient to prepare a size capable of storing 15 pixel coordinates per entry of the table. Moreover, since the total number of pixels is 49, 6 bits may be prepared to represent one pixel coordinate. Therefore, it is sufficient for the size of the pixel coordinate table 3 to be 12 Kbytes as calculated by (Equation 2).

[0017]

[Equation 2]

Table 1 shows the size of the coordinate conversion table 3 roughly estimated in the same manner as the above method for m = 3, 4, 5, and 6. If the size of m is determined in consideration of the size of the memory that can be secured in the pixel coordinate table, a feasible pixel coordinate device can be created.

[0019]

[Table 1]

As described above, according to this embodiment, by providing the pixel coordinate table, the pixel coordinates inside the polygon and the pixel coordinates of the edge can be obtained without performing complicated calculations.

[0021]

As is apparent from the above description, the pixel coordinate calculation device of the present invention and the image generation device using the same are:
By using the pixel coordinate table when calculating the pixel coordinates, the pixel coordinates of the inside and edges of the polygon can be calculated for a small polygon without performing complicated calculations, so that the pixel coordinate calculation can be performed efficiently. It is possible to realize image generation capable of high-speed image processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image generating apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of obtaining the pixel coordinates of a triangle by the first pixel coordinate calculation device in the embodiment.

FIG. 3 is an explanatory view showing an example of a polygon selecting method of a polygon selector in the embodiment.

FIG. 4 is a block diagram showing a configuration of a conventional pixel coordinate calculation device.

FIG. 5 is an explanatory diagram showing an example of obtaining pixel coordinates in the conventional pixel coordinate calculation device.

[Explanation of symbols]

 1 polygon selector 2 vertex coordinate converter 3 pixel coordinate table 4 pixel coordinate converter 5 first pixel coordinate calculation device 6 second pixel coordinate calculation device 7 pixel data calculator 8 frame memory

Claims (3)

[Claims] 1. A vertex coordinate converter for selecting one of the vertices of a polygon as a reference point and converting vertex coordinates other than the reference point into relative coordinates from the reference point, and the vertex coordinate converter outputs A pixel coordinate table for obtaining the relative coordinates from the reference point of the pixels forming the inside of the polygon and the edge from the relative vertex coordinates, and the pixel for converting the relative pixel coordinates obtained from the pixel coordinate table into absolute pixel coordinates. A pixel coordinate calculation device having a coordinate converter. 2. A pixel data calculator for calculating pixel data for a pixel having pixel coordinates obtained from the pixel coordinate calculator according to claim 1, and a frame memory for storing a calculation result of the pixel data calculator. An image generation device provided. 3. A polygon selector for selecting one of the vertices of a polygon as a reference point and selecting a polygon having a distance from the reference point to any vertex coordinate other than the reference point and having a fixed value or less. The pixel coordinate calculation device according to claim 1 for performing coordinate calculation for a polygon selected by the polygon selector, the second pixel coordinate calculation device for performing coordinate calculation for a polygon that is not selected, An image generation apparatus comprising: a pixel data calculator that calculates pixel data for pixels having pixel coordinates obtained from the first and second pixel coordinate calculators; and a frame memory that stores a calculation result of the pixel data calculator.