JP2806185B2 - Polygon filling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for filling the inside of a polygon in the field of computer DallaFix.

[0002]

2. Description of the Related Art Conventionally, many algorithms have been proposed as a method for filling the inside of a polygon. One of the very simple methods is the edge fill algorithm. Hereinafter, a method of filling the inside of a polygon by the edge fill algorithm will be described with reference to the drawings.

FIG. 7 is a block diagram showing the configuration of a conventional internal painting method, and FIG. 8 is a processing flowchart of FIG. In FIG. 7, 1 is a vertex coordinate table, 2 is a trapezoidal coordinate generating means,
Reference numeral 6 denotes a data inversion writing means, and reference numeral 7 denotes an image memory composed of 1 bit / pixel.

The image memory 7 is a memory composed of 1 bit / pixel, and stores image data in a bit image. The vertex coordinate table 1 stores the coordinates of the vertices of the polygon, and it is assumed that each coordinate is stored in order according to the connection of each side. The trapezoidal coordinate generation means 2
The coordinates of two vertices constituting each side are sequentially extracted from the vertex coordinate table 1, and a horizontal line is drawn from the two vertices to a straight line parallel to the Y-direction coordinate axis defined near the polygon. The coordinates of the points are calculated sequentially.

In this processing, first, coordinates of points on a side specified by two vertexes are sequentially generated. For this coordinate generation,
(Digital Differential Ana
(lyzer) algorithm.
Since the DDA algorithm is a known fact, refer to "Practical Computer Graphics" (Nikkan Kogyo Shimbun) or the like. Next, coordinates of points on a straight line drawn horizontally from a point on the generated side to a straight line parallel to the Y-direction coordinate axis are sequentially generated. This series of processing is repeated for all points on the side. The data inversion writing means 6 inverts data in the image memory 7 corresponding to the coordinates generated by the coordinate generation means 2 in the trapezoid.

These are processed according to the flowchart of FIG. In the figure, steps 12, 13, 31, and
The processes of 32, 22, and 23 are processes performed by the trapezoid-in-coordinate generation unit 2, and the process of step 33 is a process performed by the data inversion writing unit 6.

Here, a case where the inside of a star-shaped polygon P1P2P3P4P5 as shown in FIG. 9 is painted will be described. The coordinates of the vertices P1P2P3P4P5 of the polygon are stored in the vertex coordinate table 1 in order, and the coordinates P1 (X1, Y1), P2 (X2,
Y2),..., P5 (X5, Y5). Further, a straight line L parallel to the Y coordinate axis is defined near the polygon, and the X coordinate of this straight line is X0.

First, initialization is performed in step 11, and all the areas required for this processing in the image memory 7 are initialized to "0". In this case, since a pentagonal figure is handled, N
= 5, and the variable for counting the vertices is n = 1.

Next, at step 12, the vertex coordinate table 1
, Two coordinates P1 (X1, Y1), P2 (X
2, Y2). In step 13, the Y coordinate of the two coordinates taken out is compared. Step 2 if Y1 = Y2
3 and the following processing is performed if Y1 = Y2 is not satisfied. In step 31, points on the straight line P1P2 are sequentially generated one by one. As described above, the DDA algorithm is used for this generation. This point is defined as Pm (Xm, Ym) (see FIG. 4A).

After initializing X to X0 in the next step 32, in a step 33, a point P (X, Y
Invert the data of m). In the next step 22, the processing of step 33 is repeated while incrementing X while X ≦ Xm. As a result, the point on the horizontal line drawn from Pm to the straight line 1 is inverted.

Further, by sequentially performing the processing of steps 31 to 33 and 22 for all points on the straight line P1P2, all the points inside the trapezoid formed by drawing a horizontal line from the respective P1 and P2 to the straight line L are inverted. Is done.

In step 23, n is incremented and n
By repeating the processing of steps 12 to 22 until = N, these processings are performed for all sides of the polygon. Here, when n = N, n + 1 = 6. Therefore, in this case, n + 1 is treated as 1.

FIGS. 9A to 9F show changes in data in the image memory 7 due to the above processing. As can be seen from this figure, when the points inside the trapezoid formed by the corners and the straight line L are reversed, the result finally becomes as shown in FIG. 9 (f). In actual filling, the inside of the polygon can be filled by performing the drawing processing of the filling pattern only for the region of “1” based on the present data.

[0014]

As shown in FIGS. 10 (a) and 10 (b), the above-mentioned method for filling the inside of a polygon includes two fillings, an even-odd rule and a non-zero winding rule. There is a way. The fill by the edge fill algorithm described with reference to FIG. 9 is a fill that implements the even-odd rule. However, if there is a closed space inside the polygon, it cannot be filled.

In recent years, outline font processing for generating a character by defining a character with outline data and filling the inside of the character, X-Window, Postscript, etc.
In computer graphics processing such as t
Filling with both the even-odd / non-zero winding rules is defined as being used and needs to be achieved.

The above-described edge fill algorithm is known as a very simple method, but cannot be applied to a non-zero winding rule. Therefore, it cannot be used in recent computer graphics processing.

It is an object of the present invention to resist the internal polygon filling device which makes use of the simple processing of the edge fill algorithm to realize a non-zero winding rule.

[0018]

The polygon filling device of the present invention comprises an image memory composed of n bits / pixel (n is a natural number), and vertex coordinates for storing vertex coordinates of the polygon to be filled. Table, direction vector determining means for determining a direction vector of each side of the polygon according to the vertex coordinate table, and one vertex of the polygon
Coordinate generating means for generating coordinates of points inside a trapezoid obtained by drawing a horizontal line from two vertex coordinates constituting each side of the polygon to the straight line and defining a Y-direction coordinate axis passing through as one straight line And arithmetic operation writing means for performing an arithmetic operation on a point inside the trapezoid generated by the coordinate generation means in the trapezoid in accordance with the result of judgment by the direction vector judgment means and writing the result in the image memory. .

[0019]

DETAILED DESCRIPTION FIG. 1 is filled-polygon instrumentation relevant to the present invention
Block diagram showing the configuration of a location, FIG. 2 is a flowchart describing the processing of FIG. In the drawing, one vertex coordinate table, 2 a trapezoidal coordinate generating means, 3 a direction vector judging means, 4 an arithmetic operation writing means, and 5 an image memory composed of n bits / pixel. The vertex coordinate table 1 and the trapezoidal coordinate generating means 2 have the same configuration as in FIG.

The image memory 5 is a memory composed of n bits / pixel (n is a natural number), and can store image data as a bit image as n-bit multi-value data for one pixel. Direction vector determination means 3
Determines the Y-direction vector of each side of the polygon from the two vertex coordinates from the vertex coordinate table 1.

The arithmetic operation writing means 4 performs the following processing on the data in the image memory 5 corresponding to the coordinates generated by the coordinate generating means 2 in the trapezoid, based on the result of determination by the direction vector determining means 3. If the Y direction vector is a positive side, the data in the image memory 5 for the point inside the trapezoid generated based on that side is incremented by "+1". When the Y direction vector is a negative side, the data in the image memory 5 for the point inside the trapezoid generated based on the side is set to "-1".

Here, a case where the inside of a star-shaped polygon P1P2P3P4P5 as shown in FIG. 3 is painted will be described. Also, the vertex coordinate table 1 contains the vertex P1P of the polygon.
The coordinates of 2P3P4P5 are stored in order, and the respective coordinates are P1 (X1, Y1), P2 (X2, Y2),
.. P5 (X5, Y5), a straight line L parallel to the Y coordinate axis is defined near this polygon, and the X coordinate of this straight line is X0.

First, the initialization in step 11 of FIG. 2 and the steps 12 to 1 performed by the trapezoidal coordinate generation means 2
The processing by 5, 17, 18 is the same as that of the prior art. The difference is that the processing of steps 14 to 16 by the direction vector determination means 3 is inserted between steps 13 and 17, and the processing of step 33 is changed to the processing of steps 19 to 21 by the arithmetic operation writing means 4. . Here, the direction vector determining means 3 and the arithmetic operation writing means 4
Will be described in detail.

The processing up to step 13 is performed in the same manner as in the conventional explanation. In the next step 14, the coordinates Pn (Xn, Yn) and Pn + 1 of the two vertices extracted in step 12
For (Xn + 1, Yn + 1), Yn-Yn + 1 is calculated, and it is determined whether the result is positive or negative. If the result is positive, the Y direction vector of the side formed by PnPn + 1 is negative, and the process proceeds to step S15. If the result is negative, the Y direction vector of the side formed by PnPn + 1 is positive, and the process proceeds to step S16.

In step 15, "-1" is substituted for the variable data for storing the Y direction vector, and in step 16, "+1" is substituted. Steps 17 and 18 are processed in the same manner as in the prior art.

In step 19, the value of the variable data is determined. If this data is +1 the process proceeds to step 20; if the data is -1 then step 21
Transfer processing to In step 20, the data corresponding to the point P (X, Ym) on the image memory 7 is incremented by one, and
At 1, the data corresponding to the point P (X, Ym) on the image memory 7 is decremented by 1.

Thereafter, the processing of steps 19 to 21 is repeated while incrementing X in step 22 while X ≦ Xm. As a result, all points on the horizontal line drawn from Pm to the straight line L are incremented by +1 or -1. Steps 17 to 22
The above process is sequentially performed on all points on the straight line PnPn + 1, so that all points in the trapezoid formed by drawing a horizontal line from each of the points Pn and Pn + 1 to the straight line L are incremented by +1 or -1.

Further, the processing of steps 12 to 23 is
These processes can be performed for all sides of the polygon by repeating the same process as in the related art.

FIGS. 3A to 3F show changes in data on the image memory 5 due to the above processing. As can be seen from this figure, a point inside the trapezoid formed by each side and the straight line L is determined as '+1' based on the determination result of the direction vector determining means 3.
Or, when the arithmetic operation is performed with '-1', finally, FIG.
(F). In actual painting, the inside of the polygon can be painted by drawing a painting pattern only for an area other than '0' based on this data.

FIG. 4 is a flowchart for explaining the process of Kazumi施例of the present invention, FIG 5 is a coordinate diagram for explaining the processing of the trapezoid in the coordinate generating means 2 in FIG. 4, FIG. 6 illustrates the process of FIG. 4 It is a coordinate diagram. The configuration of the present embodiment is the same as that of the block of FIG. 1 except for the processing of the trapezoidal coordinate generating means 2.

FIG. 5 (a) shows the processing of the trapezoidal coordinate generating means 2 of this embodiment. This processing is performed in step 17
The straight line PnPn + 1 must always be on the right side of the straight line L (on the positive side in the X-direction coordinate axis).

In the processing of the trapezoidal coordinate generation means 2, steps 24 and 25 are added between steps 20 and 21 and step 22, as shown in the figure. As a result, in step 24, the magnitudes of Xm and Xo are compared, and
If o ≦ Xm, X is incremented in step 22 as in the first embodiment, and if Xo> Xm, X is incremented in step 25.
Is decremented. If Xo> Xm, steps 19 to 25 are repeated while X ≧ Xm. As a result, even when the straight line PnPn + 1 and the straight line L intersect as shown in FIG. 4B, coordinates between the straight lines can be generated.

Here, as in the case of FIG. 1 , consider the case where the inside of the star-shaped polygon P1P2P3P4P5 is painted. Here, a straight line L parallel to the Y-direction coordinate axis is defined inside the polygon as shown in FIG. As described above, the trapezoid-in-coordinate generation unit 2 can perform processing even when the straight line L intersects with each side of the polygon, and thus such a definition is possible. FIGS. 6A to 6F show how the polygon is processed in accordance with the flowchart of FIG. 4, and FIG. 6F shows the final result. As in the case of FIG. 1, the inside of the polygon can be actually filled by performing a drawing process of a fill pattern only for an area other than “0” based on the present data.

According to the present embodiment, compared with the case of FIG. 1, it is possible to reduce the unnecessary write processing for the polygon outside, therefore, it is possible to increase the speed of processing than the case of FIG. 1 .

[0035]

As described above, according to the present invention, it is possible to realize the filling by the non-zero winding rule without impairing the feature of the simplicity of the processing of the edge fill algorithm. In particular, this method can be easily realized in a device provided with a drawing means by arithmetic operation and a frame memory corresponding to a multi-valued image, and the non-zero winding rule, which was impossible with the edge fill algorithm, can be used. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration of a polygon filling device related to the present invention.
Block diagram showing the.

FIG. 2 is a flowchart showing a process of the apparatus of FIG. 1;

FIG. 3 is a coordinate diagram for sequentially explaining graphic processing in the apparatus of FIG. 1;

FIG. 4 is a flowchart that describes the process of Kazumi施例of the present invention.

FIG. 5 is a coordinate diagram showing processing of a trapezoidal coordinate generating means 2 in the embodiment of FIG. 4;

FIG. 6 is a coordinate diagram for sequentially explaining graphic processing in the embodiment of FIG. 4;

FIG. 7 is a block diagram showing components of a conventional polygon filling method.

FIG. 8 is a flowchart for explaining FIG. 7;

FIG. 9 is a coordinate diagram for sequentially explaining the graphic processing in FIG. 7;

FIG. 10 is a coordinate diagram showing an example of filling a polygon by both conventional even-odd rules and non-zero winding rules.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertex coordinate table 2 In-trapezoid coordinate generation means 3 Direction vector determination means 4 Arithmetic operation writing means 5 Image memory (n bits / pixel) 6 Data inversion writing means 7 Image memory (1 bit / pixel) 11-25, 31- 33 processing steps

Claims (1)

(57) [Claims] 1. An image memory composed of n bits / pixel (n is a natural number), a vertex coordinate table for storing vertex coordinates of a polygon to be filled, and each side of the polygon according to the vertex coordinate table. Direction vector determining means for determining a direction vector, and one vertex of the polygon
And trapezoidal in the coordinate generating means for generating a trapezoidal internal point coordinates obtained by subtracting a horizontal line from the two vertex coordinates the Y-direction coordinate axis is defined as one straight line constituting the sides of the polygon to the straight line passing through Arithmetic write means for performing an arithmetic operation on a point inside the trapezoid generated by the coordinate generating means in the trapezoid according to the result of the determination by the direction vector determining means and writing the result into the image memory. Square filling device.