JPS63133276A - Divided display system for concave polygon - Google Patents

Abstract

PURPOSE:To perform high-speed processing with a divided display system for concave polygon with reduction of the display processing value, by integrating plural truncatable triangles into a convex polygon when a division is carried out to convert the concave apexes of the concave polygon into convex apexes. CONSTITUTION:An apex convex/concave deciding part I1 decides whether a certain apex is equal to a convex or concave apes for a concave polygon described as a string of given coordinate values. At the same time, an apex convex/concave deciding part II2 decodes whether a 2nd apex adjacent to a certain apex is equal to a convex or concave apex. An enclosure deciding part 3 decides whether other apexes are included or not in a triangle formed by a 3rd apex adjacent to the 2nd apex and this 2nd apex. A concave polygon is not immediately divided by a dividing part 6 although a division deciding part 4 decides a dividable state. Thus the dividing operation is held. An integrating part 5 decides the conditions to end said holding state. Then the integrated plural triangles are divided by the part 6 in the form of a single convex polygon when said holding state is through.

Description

[Detailed Description of the Invention] [Summary] In image processing, when displaying a polygon given as a sequence of coordinate values of vertices as a figure, it is relatively easy to display it if it is a convex polygon. Although this is possible, in the case of a concave polygon, it is difficult to directly display it, so a method is used in which a triangle is cut out from a portion having concave vertices. When displaying a concave polygon using this method, if the target concave polygon has a complex shape, the number of divisions will increase, the amount of processing required to display it will increase, and the processing speed will be slow. There was a problem.

In order to solve these conventional problems, the present invention integrates triangles to generate a convex polygon and then displays it, thereby reducing the amount of processing involved in display and achieving high-speed processing. This paper discloses a method for displaying concave polygons that has been made possible.

[Industrial Field of Application] The present invention relates to the control of graphic display devices, and particularly to a control method that can efficiently display concave polygons.

[Prior Art] In graphic display devices, directly displaying concave polygons requires an enormous amount of processing, so it is often divided into convex polygons that can be displayed relatively easily before displaying them. ing. At this time, since an increase in the number of divisions leads to an increase in the amount of subsequent processing, it is desirable to keep the number of divisions as small as possible.

FIG. 4 is a block diagram illustrating a conventional concave polygon division method, in which reference numeral 51 denotes a vertex unevenness determination unit (■), 52 a vertex unevenness determination unit (■), 53 an inclusion determination unit, 54 a division determination unit, and 55 represents a dividing part.

In FIG. 4, for a concave polygon described as a sequence of given coordinate values, a vertex unevenness determining unit I51 determines whether a certain vertex is a concave vertex or a convex vertex, and the vertex unevenness determining unit [In 52, it is determined whether the second vertex adjacent to the vertex is a concave vertex or a convex vertex.

The inclusion determining unit 53 further determines whether or not another vertex is included within the triangle formed by the third vertex adjacent to the second vertex and the two vertices.

The inclusion determination unit 54 determines that the vertex is determined to be a concave vertex by the vertex unevenness determination unit 151, the vertex is convex by the determination by the vertex irregularity determination unit I[52, and furthermore, the inclusion determination unit 53 determines that the vertex does not include other vertices. The above-mentioned operation in which the division unit 55 determines that the polygon is divisible and cuts out the corresponding triangle from the original polygon will be further explained using an actual concave polygon as shown in FIG. 5 as an example. In the same figure, P1 to P8 indicate the respective vertices, and if we are currently paying attention to the vertex P1t, the vertex P unevenness determination unit 51 identifies that the vertex P1 is a concave vertex, and determines the vertex unevenness. In the section 1152, the vertex P2
Identify that is a convex vertex.

Furthermore, the inclusion determining unit 53 determines whether or not another vertex is included within the triangle having vertices Pl, P2, and P3. (In this example, no other vertices are included)
Based on the above conditions, the division determination unit 54 determines the vertices Pi, P2. P
3 is determined to be divisible, and the dividing unit 55 cuts out the triangle.

The above process is repeated until concave vertices become convex vertices as a result of division, and when all vertices become convex vertices, the process ends.

[Problems to be solved by the invention] In the conventional concave polygon division method as described above,
The unit of cutting to change one concave vertex to a convex vertex is a triangle with the least number of angles in a polygon, so division efficiency is poor, and in the case of a concave polygon with a complex shape, it is divided into many triangles. As a result, the amount of processing involved in displaying increases, resulting in a problem that the display speed is slow.

In view of such conventional problems, the present invention provides a graphic display device that can display even complex-shaped concave polygons.
It is an object of the present invention to provide a concave polygon division display method that can display efficiently and quickly.

[Means for Solving the Problems] According to the present invention, the above-mentioned object is as described in the claims. The method includes a vertex unevenness determination unit I that determines whether a certain vertex is a concave vertex or a convex vertex, and a vertex irregularity determination unit I that determines whether a second vertex adjacent to the vertex is a concave vertex or a convex vertex. A vertex unevenness determination unit (2) determines whether the vertex is a point, and another vertex is included inside the triangle formed by the three vertices, the third vertex adjacent to the second vertex and the above two vertices. an inclusion determination unit that determines whether or not each vertex is uneven;
and a division determination unit that determines whether the triangle is separable based on the determination by the inclusion determination unit, and whether or not a plurality of separable triangles can be integrated to form a convex polygon. This is achieved by a concave polygon division display method characterized by comprising a merging section that determines the combinable triangles and a means for integrating combinable triangles and displaying them as a convex polygon.

[Function] FIG. 1 is a principle block diagram of the concave-line rectangular division method of the present invention, in which 1 is the apex unevenness determination section I, 2 is the apex unevenness determination section 1
, 3 represents an inclusion determination unit, 4 represents a division determination unit, 5 represents an integration unit, and 6 represents a division unit.

In Fig. 1, for a concave polygon described as a sequence of given coordinate values, the vertex unevenness determination unit ■1 determines whether a certain vertex is a concave vertex or a convex point, and determines whether the vertex is uneven. The determination unit (2) determines whether the second vertex adjacent to the vertex is a concave vertex or a convex point.

The inclusion determining unit 3 further determines whether another vertex is included within the triangle formed by the third vertex adjacent to the second vertex and the two vertices.

The division determination unit 4 determines that the vertex unevenness determination unit 11 determines that the vertex is a concave point, the vertex unevenness determination unit 2 determines that it is a convex point, and the inclusion determination unit 3 determines that it does not include other vertices. When this happens, the corresponding triangle is determined to be divisible.

In the present invention, even if the division determination section 4 determines that "division is possible", the division section 6 does not immediately perform division, but suspends the division. The conditions for terminating the reservation are determined by the integrating unit 5. When the retention is completed, the plurality of integrated triangles are divided into one convex polygon by the dividing unit 6.

[Embodiment] FIG. 2 is a block diagram of an embodiment of the present invention, and shows 1 to 1.
Reference numeral 6 is the same as in the case of FIG.
11 is a frame buffer, and 12 is a display tube (abbreviated as CRT in the figure).

In FIG. 2, for a concave polygon described as a sequence of given coordinate values, the vertex concave/convex determining unit 11 determines whether a certain vertex is a concave vertex or a convex point, and If it is a vertex, it outputs "1", and the vertex unevenness determining unit (2) determines whether the second vertex adjacent to the vertex is a concave vertex or a convex point, and determines whether it is a convex point. If so, output "1".

The inclusion determining unit 3 further determines whether another vertex is included in the triangle formed by the third vertex adjacent to the second vertex and the two vertices, and determines whether it is a cup. If it is not included, "1" is output.

In division determination @4, when the outputs of the above-mentioned parts are all "1", it is determined that the triangle can be divided and outputs "1'°".

The integrating section 5 is a section that integrates these triangles, and is constructed as shown in FIG. 3.

In FIG. 3, reference numeral 13 denotes a temporary dividing section, which sets a temporary dividing line for dividing the triangle when the division determining section 4 determines that the triangle is "divided".

Reference numeral 14 denotes a vertex unevenness determination unit (2) that determines the unevenness of the third vertex. Note that if the division determination unit 4 determines that the vertex is not divided, and if the apex unevenness determination unit m determines that it is concave, the suspension of division is terminated and the process proceeds to the integration determination unit. Convex”
If it is determined that this is the case, the suspension is continued and the process of making the first vertex a convex vertex is proceeded.

Reference numeral 15 denotes an integration determination unit which checks whether the sum of the interior angles between the first vertices of the temporarily divided triangle is an acute angle or an obtuse angle. If it is an acute angle, the plurality of subdivided triangles are sent to the dividing section 6 as one convex polygon. If it is an obtuse angle, a differential dividing line that is an acute angle is searched, and the triangles before and after the dividing line are sent to the dividing unit 6 as convex polygons.

The dividing unit 6 cuts out the convex polygon sent from the integrated determining unit 15 from the original concave polygon, returns the process to the vertex unevenness determining unit (2), and proceeds to convert the first vertex into five vertices.

The convex polygon cut out by the dividing section 6 is registered in the segment buffer 7 as a graphic element.

The coordinate transformation/clipping section 8 performs coordinate transformation on the figure, and as a result, the portions that protrude from the display area are cropped.

The fill section 9 and the DDAIO section give brightness to the points inside the polygon through their interaction, and the frame buffer l
'Write to l.

CRT 12 displays the contents of frame buffer 11.

[Effects of the Invention] As explained above, according to the method of the present invention, when dividing a concave polygon to change its concave vertices to convex vertices, a plurality of cuttable triangles are integrated to form a convex polygon. Since the processing amount for display is smaller than that of the conventional method, it is possible to display concave polygons at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of the integrating section.
FIG. 4 is a diagram explaining a conventional concave polygon division method, and FIG. 5 is a diagram showing an example of concave polygons. 1... Vertex unevenness determination unit 1.2... Vertex unevenness determination unit ■, 3... Inclusion determination unit, 4...
...Division determination section, 5... Integration section, 6...
・Dividing section, 7... Segment buffer, 8.
...Coordinate transformation/clip part, 9... Surface painting part, 10... Digital differential analyzer, 11.
... Frame buffer, 12 ... Display tube, 13 ... Differential division section, 14 ... Vertex unevenness determination section ■, 15 ...... Integrated Judgment Unit 6'-N Agent Patent Attorney Sada Igata Figure 3 Diagram showing the purchase of each part of the filtration Figure 3 Conventional concave polygon separation method Figure and 3 Diagram showing 7 rows of concave polygon Figure 5

Claims (1)

[Claims] A method for displaying a polygon as an image based on image data of the polygon given as a sequence of coordinate values of vertices, the method comprising: determining whether a certain vertex is a concave vertex or a convex vertex; a vertex unevenness determination unit I (1) that determines whether a second vertex adjacent to the vertex is a concave vertex or a convex vertex; an inclusion determination unit (3) that determines whether or not another vertex is included within a triangle formed by the three vertices that are the third vertex adjacent to the vertex and the two vertices; Unevenness determination unit I (1), apex irregularity determination unit II (
2), and a division determination unit (3) that determines whether the triangle is separable based on the determination of the inclusion determination unit (3).
4), an integrating unit (5) that determines whether a plurality of separable triangles can be integrated to form a convex polygon, and means for integrating the integrable triangles and displaying them as a convex polygon. A concave polygon division display method characterized by comprising: