JPH06150015A - Creation method for file polygon - Google Patents

Abstract

PURPOSE:To enable high-speed painting-out (fill plotting) regardless of the shape of a polygon by creating fill plotting data inside a memory and exclusively ORing respective line segments concerning the respective fill plotting data. CONSTITUTION:A fill plot processing area including the polygon is decided, and the fill plotting data of an area held between the respective line segments constituting the polygon, two straight lines pulled out from both of terminals of the line segment in a specified direction and the outer edge of the processing area are created inside the memory. Then, the respective line segments are exclusively ORed concerning the respective fill plotting data. Namely, this processing is applied to a star-shaped polygon 2 (which apexes are shown by P1-P5) composed of a pentagon and five triangles and when creating a fill polygon 2', the fill polygon 2' is created by successively exclusively ORing fill plotting data 21-25 formed by respective line segments concerning the star- shaped polygon 2 created inside a fill plotting processing area 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for creating fill polygons (painted polygons) in computer graphic processing, and a method for creating fill polygons capable of high-speed painting (painting) regardless of the shape of the polygons. Regarding

[0002]

2. Description of the Related Art Conventionally, when a fill polygon having an arbitrary shape is created, a method of scanning the horizontal direction to obtain a paint area and sequentially shifting the area in pixel units in the vertical direction to paint the entire polygon has been adopted. ing. In this method, the drawn polygon is horizontally scanned in a predetermined area in pixel units in the vertical direction, the scan line is intersected with the polygon, and the odd-numbered intersections and even-numbered intersections counting from the smallest X coordinate are counted. Pixels existing at the intersections are painted along the scan line.

For example, as shown in FIG. 7, a polygon having an arbitrary shape (in this figure, a star-shaped polygon 6 having five triangles and vertices Pn1 to Pn5 and one pentagon).
, Is scanned by a horizontal line whose Y coordinate is Yn, the scan line L becomes a star polygon 6 and Pn1, Pn.
Since it intersects at 2, Pn3, Pn4, Pn1 to Pn
2, and Pn3 to Pn4 are painted. And
The star-shaped polygons 6 are formed by shifting the scanning of this horizontal line in the vertical direction pixel by pixel.
The inside of the prism is painted. Note that FIG. 7 shows a state in which painting is performed up to the height of Yn while scanning from the upper side to the lower side. Such a painting method is used in various kinds of software, and it is relatively easy to implement it as hardware (incorporating the painting function into a graphics processor).

However, the above painting method has the following drawbacks. (1) A memory area (table) for storing the intersection of the scan line L and the polygon 6 is required. Therefore, the scan line L of a certain Y coordinate and the line segments (P1-P2, P4-P5, P2-
X coordinate (Xn1, Xn) of the intersection with P3, P5-P1)
2, Xn3, Xn4) must be obtained and registered in the table. Therefore, the number of polygon lines that can be handled must be limited depending on the size of the table. (2) Since the number of calculations is large, the painting data of the area sandwiched between each line segment forming the polygon, two straight lines drawn from both ends of the line in a specific direction, and the outer edge of the painting processing area Is slow to create in memory. That is, the calculation for determining whether or not a certain Y coordinate includes a line segment forming the polygon 6, the calculation for the X coordinate of the intersection, the calculation for sorting the intersection in ascending or descending order of the X coordinate, etc. It is necessary to perform the same number of times as the number of pixels arranged in the Y direction in the processing area.

In contrast to such a method, a method in which a polygon having an arbitrary shape is decomposed into a large number of triangles and the inside of each triangle is painted is known, but this method requires a complicated algorithm. Therefore, there is a possibility that a bug will occur in the painting program.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for creating a fill polygon that enables high-speed painting (painting) regardless of the shape of the polygon.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, in a fill polygon creating method of the present invention, first, in a first step, a painting processing area including a polygon is defined. The shape of the painting processing area is usually a rectangle (including a square) whose side direction is the pixel arrangement direction (generally, the horizontal and vertical directions), but the shape is not necessarily limited to this. For example, even if the shape is circular, it is possible to create a fill polygon. The position and size of the painting processing area may be determined at the same time when the drawing of the polygon is completed. For example, when the shape data of the polygon created in advance exists in the memory, When painting, it is determined by designating a polygon.

In the second step, the painting data of the area sandwiched by each line segment forming the polygon, two straight lines drawn from both ends of the polygon in a specific direction, and the outer edge of the processing area are stored in the memory. To create.

Here, the specific direction is usually the direction in which the pixels are arranged (horizontal or vertical direction) for ease of processing. When the painting processing area is a rectangle having horizontal and vertical sides, the area (painting area) formed by each line segment forming a polygon and one side of the rectangle has the line segment as a hypotenuse, It becomes a right-angled trapezoid (a trapezoid in which one base angle is a right angle) with two straight lines drawn horizontally from both ends of the line segment as the upper base and the lower base. When the outer edge of the painting processing area is in contact with a line segment that constitutes a polygon, the painting area is a right angle with the line segment as a hypotenuse and a straight line drawn from one end of the line segment as the base. It becomes a triangle. Since the trapezoidal painted area is a combination of a triangle and a quadrangle, in this case, the painted area can be composed of only the triangle and the quadrangle. For triangles and quadrangles, a processor dedicated to painting is also provided, so that painting processing can be performed at higher speed.

In the third step, an exclusive OR is calculated for each drawing data for each line segment. In this calculation, it is arbitrary for which line segment the paint data is created first. For example, the line segment A having three polygons,
In the case of being composed of B and C, it is possible to first create the painting data for C and then for B, and take the exclusive OR of these, or the painting data for B first and then A. May be created and the exclusive OR of these may be taken.

The polygon is composed of straight lines, but a spline curve and the like can be made into a set of straight lines when viewed microscopically. Therefore, the present invention includes figures that are broadly constructed by curves. Further, the polygon may be a normal quadrangle, a pentagon, or a figure in which the line segments forming the polygon do not intersect, or may be a figure in which the line segments intersect, such as the numeral “8”. Good. Normally, three or more line segments are required for a polygon, but a figure (L-shaped) composed of two line segments is also included in the polygon of the present invention. In this case, the present invention is applied by considering the virtual line connecting the open ends of the line segments as the line segment forming the polygon. Furthermore, the present invention can be applied to a figure (for example, a U-shape, etc.) that is not completely closed even if it is composed of three or more line segments. The present invention is also applied to such an unclosed figure by regarding a virtual line that connects the tips of line segments that are not connected to any line segment as a line segment that constitutes a polygon.

In the present invention, the required memory area depends on the size of the polygon to be created, but the number of polygon line segments that can be handled is not limited. Therefore, it is possible to easily create a polygon having complicated spline curves. Further, according to the present invention, since it is not necessary to perform complicated calculation such as obtaining an intersection between a scan line and a line segment forming a polygon, a fill polygon can be created at high speed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The flow chart of FIG. 1 and the painting process chart of FIG.
The case of painting the polygon 1 shown in (3) will be described in detail. FIG. 6 shows an example of hardware used for implementing the fill polygon creating method of the present invention. In the figure, the bus 51 includes a CPU 52, a ROM 53, a RAM 54, an input device 55,
It is shown that the output device 56 is connected. CPU
Reference numeral 52 denotes RA from the ROM 53 or an auxiliary storage device (not shown).
It operates according to the program read in M54. This program receives data from an input device 55 such as a mouse, a tablet, a keyboard and performs calculations, transfers the data to an output device 56 such as a display device and a printer, RAM 54 and the auxiliary storage device. Write the calculation result to etc. In this embodiment,
The processes and judgments described below are performed by the program written in the ROM 53 or the RAM 54 by the CPU 52. Further, the coordinates of each vertex of the polygon are preliminarily input and stored in the RAM 54. Note that S1 to S6 described below show the flow of processing in the present invention, as shown in FIG.

(1) In S1, the painting processing area is first determined. This processing area can be determined by the coordinates of each vertex of the polygon stored in the RAM 54. In FIG. 2, for convenience of description, the painting processing area 10 is set to be slightly larger than the maximum value in the X and Y directions of the polygon 1 and slightly smaller than the minimum value in the X and Y directions. It is needless to say that the height can be determined in accordance with the maximum and minimum values in the X and Y directions. Note that here, the maximum values in the X and Y directions of the painting processing area 10 are respectively set to X.
max and Ymax, and the minimum values in the X and Y directions are Xmin and Ymin, respectively.

(2) In S2, it is judged whether or not there is a vector to be processed next. If the vector exists, the vector to be processed [(Xα, Yα),
(Xβ, Yβ)] (α, β = 1, 2, ..., α ≠ β)
Is performed. Here, the vector [(Xα,
Y [alpha]), (X [beta], Y [beta])] is a coordinate display of a line segment to be painted, and is represented by Table 1 in this embodiment.

[0015]

[Table 1] Line segment vectors P1-P2: [(X1, Y1), (X2, Y2)] P2-P3: [(X2, Y2), (X3, Y3)] -P1: [(X5, Y5), (X1, Y1)]

Since the process has just started, there is a "vector to be processed next". It is assumed that the vector to be currently processed is known from the beginning. Although there is no special rule in the order of processing, it is assumed here that the subsequent processing is performed in the order shown in Table 1 above. Therefore, first, [(X1,
Y1), (X2, Y2)] is the processing target.

(3) In S3, it is determined whether or not the Y coordinates of the vector to be processed are equal. If these coordinates are the same, the process is interrupted as will be described later, the process returns to S1, and if they are not the same, the process proceeds to the next process (S4). Here, since Y1 ≠ Y2, the process proceeds to S4.

(4) In S4, the vector [(Xα, Yα), (Xβ, Yβ)] to be processed and the coordinates (Xα, Yα), (Xβ, Yβ) at both ends of the vector are positively parallel to the X axis. Two lines drawn in the direction of the
The painting data formed in the area sandwiched between the right side parallel to the Y-axis and is stored in the memory (RAM 4). In this case, the vector to be painted is [(X1, Y1),
(X2, Y2)], the painting data is shown in FIG.
(A) As shown in the lower part (the paint data area is indicated by "1" and the non-painting data area is indicated by "0"). Then, the XOR of the paint data for this paint processing area 10 and the paint data that has already been created for the paint processing area (paint data that was created last time) is calculated. Here, "data already created" is
Since it does not exist, it is “0” for the entire painting processing area 10 (see the upper part of FIG. 3A). Therefore, in this case, the painting data after calculation is the same as the lower part of FIG. 3A as shown in the upper part of FIG.

The creation of the painting data means a painting process of a trapezoid (see the lower stage of FIG. 3A) on the memory. In this case, the trapezoidal painting may be performed by any method, or by scanning the horizontal lines by shifting them in pixel units in the vertical direction, or by separating the trapezoid into right-angled triangles and rectangles as described above. It may be drawn.

(5) Next, one column of pixels (one line) is erased or added from the upper or lower bottom of the painted trapezoidal data area (S6). In this embodiment, the XY coordinates are determined on the basis of the pixel (on the basis of the center of the pixel). Therefore, unless the erasure is performed, the entire painting process for the polygon 1 is completed. Unnecessary horizontal painting lines may appear in the non-painting area, or unwanted horizontal non-painting lines may appear in the painting area. In the present embodiment, in S5, it is determined whether Yα> Yβ, and the one column of pixels is erased or added from the upper bottom of the trapezoid. When the above relationship is established according to the case classification, the current painting data and the line segment (Xα, Yα)-(Xm
ax, Yα) is calculated with respect to the processing area where the painting is performed (S6a), and when the above relationship is not established, the current painting data and the line segment (Xβ, Yβ)-(Xmax, Yβ)
XOR with the processing area on which is painted is calculated (S6
b). After this, the processing shifts to S2. In this case, Y1
Since <Y2, the process moves to S6b, and the process shown in FIG.
The XOR of the painting data shown in the upper part and the line segment shown in the lower part of FIG. 3B is calculated, and the painting data shown in the upper part of FIG. 3C is created.

(6) Next, with respect to P2-P3, that is, the vector [(X2, Y2), (X3, Y3)], the same processing as described above is performed. That is, in S2, as shown in FIG.
As shown in (C), [(X2, Y2), (X3, Y
3)], the paint data is created (see the lower part), and the XOR between this and the paint data shown in the upper part is calculated.
As a result, the paint data is rewritten to data in which a line of "0" is formed between the two paint data, as shown in the upper part of FIG. According to the determination in S5, the process proceeds to S6a, and the painting data shown in the lower part of FIG.
XOR with the painting data shown in the upper part of FIG. 3D is calculated. As a result, as shown in the upper part of FIG. 3 (E), the line of "0" between the painting data is erased.

(7) Next, P2-P4, that is, S2 for the vector [(X3, Y3), (X4, Y4)]
The process of S3 is performed. Here, since Y3 = Y4, the vector [(X3, Y3),
The subsequent processing for (X4, Y4)] is not performed,
P4-P5, that is, the vector [(X4, Y4), (X
5, Y5)], the processing of S2, S3, S4 is performed. In S4, as shown in FIG. 3 (E), the paint data for the vector [(X4, Y4), (X5, Y5)] shown in the lower row and the already created paint data shown in the upper row are stored. XOR is calculated, and the painting data shown in the upper part of FIG.

As a result, the processing shifts from S5 to S6, and the painting data shown in the lower part of FIG. 3 (F) (the line corresponding to the upper base of the trapezoid in the lower part of FIG. 3 (E)) and the above-mentioned ( F) The XOR with the painting data shown in the upper part is calculated, and the painting data shown in FIG. 3G is created. (8) Furthermore, P4-P5, that is, the vector [(X4,
The processing of S2 is performed for Y4), (X5, Y5)]. In S2, [(X4, Y4), (X5, Y5)]
However, since it does not have the "vector vector to be processed next", the processing ends.

In FIG. 4, the processing described in (1) to (8) above is applied to a star polygon 2 (vertices are indicated by P1 to P5) composed of a pentagon and five triangles to fill a polygon. It is explanatory drawing at the time of creating 2 '. As shown in the figure, the star polygon 2 created in the painting processing area 20 is sequentially XORed with the painting data 21 to 25 formed by each line segment, and the fill polygon 2'is obtained. Created.

FIG. 5 is an explanatory diagram of a case where the processing described in the above (1) to (8) is applied to the white star polygon 3 to form the fill polygon 3 '. In the figure, the star-shaped polygon 3 created in the painting processing area 30.
The vertices (indicated by P1 to P10) are sequentially XORed with the paint data 31 to 40 formed by each line segment by a tournament method to create a fill polygon 3 '.

It is needless to say that the surface type for painting the fill polygons created as described above is not limited to so-called solid painting but also includes hatching such as striped patterns and satin finish.

[0027]

【The invention's effect】

(1) It is not necessary to perform complicated calculation such as obtaining an intersection between a scan line and a line segment that constitutes a polygon, and a fill polygon can be created at high speed with a calculation amount equivalent to that of drawing a line. (2) There is no limit to the number of polygon line segments that can be handled. Therefore, it is possible to create a polygon having a complicated spline curve. (3) Not only is it effective for graphic processing devices such as CAD because it uses a graphic processor and can be easily implemented as dedicated hardware, but it is also effective for graphic output devices such as laser printers that create outline fonts. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a processing flow of the present invention.

FIG. 2 is a diagram showing polygons exemplified for explaining an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention using the polygon of FIG.

FIG. 4 is an explanatory diagram of another embodiment of the present invention.

FIG. 5 is an explanatory diagram of still another embodiment of the present invention.

FIG. 6 is a diagram showing a hardware configuration used in the present invention.

FIG. 7 is a diagram showing a conventional polygon painting method.

[Procedure amendment]

[Submission date] December 6, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (2)

[Claims] 1. A method of painting an arbitrarily shaped polygon, comprising:
(1) a step of defining a painting processing area including the polygon, (2) each line segment forming the polygon, two straight lines drawn in a specific direction from both ends of the line segment, and an outer edge of the painting processing area. And a step of (3) calculating an exclusive OR of each painting data of each line segment in the memory, How to create. 2. A method of painting an arbitrarily shaped polygon, comprising:
(1) a step of defining a rectangular painting processing area including the polygon, (2) each line segment forming the polygon,
Creating in a memory the paint data of a trapezoidal or triangular area sandwiched between a specific side of the rectangle from both ends of the line segment and two straight lines drawn from the ends of the line segment to the side; ) A step of calculating an exclusive OR of each painting data of each line segment, and a method of creating a fill polygon.