JPH02239381A - Graphic processing system - Google Patents

Abstract

PURPOSE:To shorten a painting-out time by moving along the sides of a polygon, projecting the respective sides on X and Y axes, and deciding a convex polygon based on the number of times of changes in the moving direction on the axis. CONSTITUTION:A process move along a polygon 1 in the sequence of apexes P1, P2, P3,... PN, and P1, and the respective sides are projected on the X and Y axes. Next the number of times of changes in the moving direction of the sides projected on the X and Y axes is checked, when the number of times of the changes is, for example, <=2 for the both X axis and Y axis, the graphic is decided as the convex polygon in the painting-out processing. Thus by checking only the number of times of the changes in the side direction and deciding the convex polygon without executing a multiplying processing, the painting-out processing time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphic processing method using a computer, and more particularly to a graphic processing method for determining a convex polygon for fill-in processing from a predetermined polygon.

[Conventional technology]

Conventionally, in the filling process of a figure, convex polygons have been determined as preprocessing for the filling process in order to speed up the filling process. Figure 4 is the ninth diagram explaining how to determine this type of convex polygon. Conventionally, the cross product of vectors along the sides with P, P4, etc. If the signs of the z-axis direction components are the same until the end, it is determined to be a convex polygon, otherwise it is determined to be a concave polygon.

[Problem to be solved by the invention]

However, the conventional processing method described above calculates the outer product for the number of vertices of a polygon, so when the number of vertices of a polygon is large, the multiplication operation takes a long calculation time, which slows down the determination speed of convex polygons. There are a lot of drawbacks.

The present invention has been made to overcome these conventional drawbacks, and its purpose is to provide a graphic processing method capable of increasing the speed of determining convex polygons and significantly shortening the processing time.

[Means to solve the problem]

The present invention moves along the sides of a polygon, projects each side onto the X-axis and Y-axis, and determines a convex polygon in filling processing based on the number of changes in the movement direction on each axis. It has become.

[Effect]

Move along the sides of the polygon and project each side onto the t-X and Y axes. Next, the number of changes in the moving direction of the side projected on the X-axis and Y-axis is checked, and this number of changes is calculated as the X-axis. , and the Y axis are, for example, less than ``2'', the polygon is determined to be a convex polygon in the filling process.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIG. 1k.

FIG. 1 is the ninth diagram for explaining the graphic processing method of this embodiment, in which polygon 1 is transformed from vertex P to P2 * P3+...
・, PMIP, and each side P, P2,
The projection of P2P, ..., p7, onto the X and Y axes is shown. In this example, when projecting on the X and Y axes as described above, the movement of the projected sides The number of changes in direction is
It is calculated as required for each axis and Y axis.

Also, a change in the direction of movement is observed when moving from PM-2PN-1 to pN-;p, and a change in the direction of movement is observed when the number of changes is 2 times in total.

FIGS. 2(.) and 2(b) are diagrams each showing an example of a convex polygon in the filling process, and FIG. 2(C) is a diagram showing an example of a concave polygon. Note that Figure 2 (.) shows a geometrically convex polygon in which the sum of the interior angles is smaller than 180°, and Figure 2 (b) shows a geometrically convex polygon in which the sum of the interior angles is greater than 1800. Although it is a concave polygon, the intersection of the horizontal line H and the polygon is 12", so in this example, it is shown in Fig. 2 (b).
It is defined as a convex polygon in the filling process, including polygons such as .

As can be seen from Figures 2(a) and 1(b), the convex polygon in the filling process is such that the number of changes in the moving direction of each side projected onto the X and Y axes is @2' or less. There is. Therefore, it is possible to determine whether the polygon is a convex polygon based on the number of changes in the moving direction. In the example shown in Figure 1, the number of movements on the X-axis is "2" and the number of movements on the Y-axis is "1m," so polygon 1 is determined to be a convex polygon for filling processing. I can do it. Note that, compared to general polygon filling processing, if a convex polygon is determined, the filling processing can be performed faster.

FIG. 3 is a flowchart showing the flow of the convex polygon determination process in this embodiment, and below, based on this flowchart, how to determine a convex polygon in the filling process will be explained. In step S1 of FIG. 3, the number of changes in the moving direction CNT is initially set to @0'', and step S2
Now, initialize the side number to "1". Step S3
Now, perform projection on the X axis and write Pi+ in register WKI.
1-P1 is stored and P1+2-Pi+ is stored in register WK2.
, and in step S4 it is determined whether WKI and WK2 have the same sign. When the signs are the same, there is no change in the moving direction on the X axis, so proceed to step S5, step the side number 1 by @11, and in step S6 check whether the side number i is N or not, that is, move to the last side. Determine whether or not. If it has not moved to the last side, the process returns to step S3.

If WKI and WK2 do not have the same sign in step S4, a change in the movement direction has occurred on the The number of changes CNT is 12”
It is checked whether the polygon is greater than or equal to ゜21, and when it is greater than ゜21, the process proceeds to step S9, where it is determined that it is a concave polygon.
When the number is 21 or less, the process advances to step S5.

In this way, when it is determined in step 7'S6 that side number 1 is larger than N, it means that the number of changes CNT in the moving direction on the X axis is less than @2''. Then, the process proceeds to steps 810 to 818 to check the number of changes in the moving direction on the Y axis.

In step 810, the number of changes CNT is initialized to 101, and the number of nine sides lt-'''' is initialized to 11. Next, in step 811, the throw on the Y axis [- is performed, the register WKI Ic Pl+, -P, is stored, the register wK2 Pτ+2-P1'+, f is stored, and the step 7's is stored.
In step 12, it is determined whether WKI and WK2 have the same sign. When the signs are the same, there is no change in the movement direction on the Y axis, so proceed to step 7'S13 and change the side number 1 to @1#
In step 814, it is determined whether side number 1 is N or not, that is, whether or not the movement has only reached the last side. If it has not moved to the last side, step SllIII-
Back again.

If WKI and WK2 do not have the same sign in step 812, a change in the movement direction has occurred on the Y-axis, so the process proceeds to step S15, where the number of changes CNT is incremented by @1'. Next, in step S16, the number of changes CNT is “
It is checked whether the polygon is 2" or more, and when it is 2" or more, the process proceeds to step 817 and it is determined that it is a concave polygon.
When the value is ``2'' or less, the process proceeds to step 813.

In this way, in steps fs 1 4, the side number i
When it is determined that CNT is larger than N, it means that the number of changes CNT in the moving direction on the Y axis is also less than ""2", so it is determined in step 818 that it is a convex polygon. I can do it.

〔Effect of the invention〕

As explained above, in the present invention, the X-axis, Y-axis
Since a convex polygon in filling processing is determined only by the number of changes in the direction of the polygon's sides on the axis, the processing time can be significantly reduced compared to the conventional method.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining an example of the graphic processing method of the present invention, Figures 2 (a) and (b) are diagrams showing an example of a convex polygon in filling processing, and Figure 2 (c) is a diagram for explaining an example of a convex polygon in filling processing. FIG. 3 is a flowchart showing a process for determining a convex polygon, and FIG. 4 is a diagram illustrating a conventional graphic processing method. In the figure, 1 is a polygon, and P1 to PN are vertices of the polygon. Agent Patent Attorney Johei Yamashita

Claims (1)

[Claims] It moves along the sides of the polygon, projects each side onto the X and Y axes, and determines the convex polygon in the filling process based on the number of changes in the movement direction on each axis. A graphic processing method characterized by