JPH01155481A - Three-dimensional shape display device - Google Patents

Abstract

PURPOSE:To perform the animation display of the cut and eliminated image of a polyhedron even when a large number of ridge lines exist by suppressing a time required for a display processing by providing a means to decide whether or not the display processing and an erasing processing should be performed on each ridge line of the polyhedron, respectively. CONSTITUTION:A cross data generating means 103 decides a crossing state with the plane of each ridge line of the polyhedron, and outputs the state to a ridge line crossing state storage means 105. Also, the crossing state of the ridge line in the cut and eliminated image of one picture before is transferred to a ridge line old crossing state storage means 107 via a transfer means 106. A decision means 108 makes access to the storage means 105 and 107, and compares the present crossing state of every ridge line of the polyhedron with the crossing state of one picture before, and decides whether or not the erasing processing and a plotting processing on each ridge line is required. A shape display means 109 performs no erasing processing or plotting processing on an unrequired ridge line.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a three-dimensional graphic processing system that interactively creates a three-dimensional shape model, and is capable of rapidly displaying an image in which a polyhedral shape is cut and removed by a plane. The present invention relates to a three-dimensional shape display device.

(Prior Art) As a method for displaying an image in which a polyhedral shape is cut and removed by a plane, there is a method fully described in Japanese Patent Application No. 1988-014588 entitled "Graphic Display Device." FIG. 2 is a diagram explaining the operation of this system. The polyhedral shape is divided into the side that will be removed after cutting and the side that will remain after cutting.
All edges 201 of the polyhedron are edges 202 that can be removed.
They can be classified into remaining ridgelines 203 and ridgelines 204 that intersect with the plane. Then, the remaining edge lines 203 and the portions 205 belonging to the remaining side of each edge line that intersect with the plane are displayed on the screen, and the intersection lines 206 between the plane and each face of the polyhedron are also displayed on the screen. In this way, an image 207 in which the polyhedral shape has been cut and removed is completed on the screen.

(Problem to be solved by the invention) When the plane used for cutting is moved continuously, the displayed image of the polyhedron cut and removed also changes. In order to change the removed image, it is necessary to display the polyhedron cut and removed image at high speed.
It is also necessary to delete the image that was displayed just before.

However, in the above-described one-figure display device, it is necessary to display all of the remaining edges 203 of the polyhedron each time, and when the number of edges of the polyhedron becomes extremely large, the time required for display processing also increases. However, there was a problem in that the image could not be changed continuously in an animation style.

The purpose of the present invention is to solve these problems and to reduce the time required for display processing even when the number of edges of a polyhedron increases, and to display an animation of an image of a polyhedron cut and removed in accordance with the movement of the plane. An object of the present invention is to provide a three-dimensional shape display device that makes it possible to display a three-dimensional shape.

(Means for Solving the Problems) A three-dimensional shape display device of the present invention includes: a shape data storage means for storing shape data of a polyhedron; a plane parameter input means for inputting plane parameters of a plane cutting the polyhedron; intersection data generation means for generating intersection data between a polyhedral shape and a plane from the contents of the shape data storage means and the output of the plane parameter input means; an intersection data storage means for storing the output of the intersection data generation means; An edge line intersection state storage means for storing the intersection state of each edge of the polyhedron with a plane among the outputs of the intersection data generation means; a transfer means for saving and transferring contents; an old edge intersection state storage means for storing the intersection state of each polyhedron edge line transferred by the transfer means; the contents of the edge intersection state storage means; and the contents of the old edge intersection state storage means. a determining means for determining whether display processing and erasing processing are to be performed on each edge of the polyhedron by comparing them; It consists of a shape display means for displaying a line drawing of an image in which a polyhedral shape is cut and removed by a plane based on the content and the output of the determination means.

(effect) FIG. 1 is a block diagram showing the overall configuration of the present invention.

In FIG. 1, 101 is a shape data storage means, in which shape data of a polyhedron is stored.

Reference numeral 102 denotes a plane parameter input means, in which the plane parameters of the plane cutting the polyhedron are inputted one after another while changing little by little.

103 is an intersection data generation means, which inputs plane parameters from the plane parameter input means 102, accesses the polyhedral shape data in the shape data storage means 101,
Generate intersection data between a polyhedron and a plane. The intersection data can be composed of the intersection state of each edge line of the polyhedron and the coordinates of the intersection point, etc., which are necessary to display the cut and removed image of the polyhedron.

104 is an intersection data storage means, which stores the intersection data generated by the intersection data generation means 103.

Reference numeral 105 denotes an edge line intersection state storage means, which captures and stores the intersection state of each polyhedral edge line with a plane from among the intersection data generated by the intersection data generation means 103. The intersecting state is a distinction between whether the edge line is on the removal side, the remaining side, or intersects with the plane, with the plane as the boundary.

Reference numeral 106 denotes a transfer means for transferring the edge line crossing state, and each time new crossing state data is input to the edge line crossing state storage means 105, the old crossing state from one screen before is saved and transferred.

Reference numeral 107 is a ridgeline old intersection state storage means, and a transfer means 10
The intersection state of the edges transferred from 6 is stored.

Reference numeral 108 denotes a determining means for determining whether to perform edge line drawing or erasing processing; the edge line crossing state storage means 105 also takes in the current crossing state; the old edge crossing state storing means 106 takes in the crossing state one screen before; By comparing them, a determination signal is output as to whether to perform drawing processing or erasing processing.

109 is a shape display means, and shape data storage means 10
1 and the intersection data in the intersection data storage means 104, and based on the determination of whether or not to perform edge line drawing and erasure processing output from the determination means 108, each polyhedron in the previous screen is accessed. The edges are erased, each edge is drawn on the current screen, and the display of the polyhedron cut and removed image is updated.

When the plane used for cutting is continuously moved, the cut-and-removed image does not change suddenly each time.

For example, suppose that the image changes from FIG. 3(a) to FIG. 3(b). The changes in both are considered by dividing them into the intersection line between the plane and the three-dimensional surface, the edge line that is removed, the edge line that remains, and the edge line that intersects the plane. Edge 30 from the group of edges to be removed
1 will be removed, but the other ridge lines will not undergo any changes.

Edges 302 and 303 are added to the remaining edge group, but the other edges do not undergo any changes.
The group of edges intersecting the plane is edge 304 and edge 30.
5 is removed, ridgeline 306 is added, and other ridgelines 307
The position of the end point of the edge line 308 also changes. The group 309 of lines of intersection between the plane and the three-dimensional surface changes in number and position of end points to become a group 310 of lines of intersection.

Considering this example, of the line segments that make up the cut-and-remove image of a polyhedron, only the parts that are directly related to the plane to be cut, that is, the ridge lines and intersection lines that intersect with the plane, change; It can be seen that the ridgeline does not undergo any change. For example, in FIG. 3, portions of group 311 of residual edges remain unchanged.

In the configuration of the present invention, the intersection data generation means determines the intersection state of each edge of the polyhedron with a plane, that is, whether the edge intersects on the removal side or the remaining side, and outputs it to the edge intersection state storage means. Also, via transfer means,
The intersection state of the edges in the cut-and-removed image one screen before is transferred to the old edge intersection state storage means. The determination means accesses the edge crossing state storage means and the old edge crossing state storage means, and calculates the current crossing state and one for each edge of the polyhedron.
By comparing the intersection state in front of the screen, it is determined whether each edge line needs erasing processing and drawing processing. The shape display means does not perform erasing or drawing processing on unnecessary edges.

By adopting this configuration, the erasing and drawing processes that were conventionally performed for most of the ridge lines that do not change on the display can be omitted, so the time required to rewrite the image can be suppressed even when the number of ridge lines increases. This makes it possible to display animations of polyhedral cut and removed images.

(Embodiment) FIG. 4 is a circuit block diagram showing an embodiment of the present invention.

Reference numeral 401 denotes a plane parameter input circuit, which has a circuit configuration as described in, for example, Japanese Patent Application No. 185558/1982 "Plane Input Device", and repeatedly performs the process of inputting plane parameters from the outside and temporarily storing them. be exposed.

A shape data memory 402 stores data on vertices, edges, and faces in a polyhedral shape. Vertex ID, edge 1. D and surface ID.

403 is an edge line determination circuit which inputs the plane parameters sent from the plane parameter input circuit, accesses the shape data memory, and determines whether each edge line of the polyhedron is on the removed side of the plane, on the remaining side, or intersects. and outputs a numerical representation of the judgment result. If it intersects with Kira, the projected position data of the intersection is also output.

404 is a crossing edge matching circuit which calculates and stores all sets of crossing edges that share the same face of the polyhedron among the edges of the polyhedron.

Note that the shape data memory 402. The ridge line determination circuit 4o3° cross ridge line matching circuit 404 is based on Japanese Patent Application No. 62-01458.
This can be realized using the circuit configuration described in No. 8 1 Graphic Display Device J.

Reference numeral 405 is an edge line ID generation counter for edge line drawing, which generates all edge line IDs in order.

Reference numeral 406 is an edge line ID generation counter for transferring the crossing state, which generates all edge line IDs in order.

407 is an edge line crossing state memory, and the edge line determination circuit 40
The numerical value of the intersection state of the edges sent from 3 is stored for each edge ID. Kirani ridgeline ID generation counter 40
5 or input the edge line ID from the edge line ID generation counter 406 and output the value of the intersection state of the edge line.

408 is a data transfer circuit, and the edge line crossing state memory 4
The edge line intersection state value output from 07 is sent to the edge line old intersection state memory 409.

Reference numeral 409 denotes an edge line old intersection state memory, which stores the value of the edge line intersection state transferred from the data transfer circuit 408 according to the edge line ID inputted to the edge line ID counter 406 as well.

410 is a drawing determination circuit, and an edge line intersection state memory 40
7 and edge line old intersection state memory 409 Input the value of the current intersection state of the edge line and the value of the intersection state one screen ago, and select whether or not to delete each edge line from one screen ago as a remaining edge line on the current screen. The result of the 0 judgment that determines whether or not to draw a line segment that connects both ends of the edge line, or whether or not to draw a line segment that connects one end of the edge line and the intersection point as an intersecting edge line on the current screen,
Outputs an erase on/off signal, a residual edge drawing on/off signal, and an intersecting edge line on/off signal.

Reference numeral 411 denotes a remaining edge line drawing circuit, into which the edge line ID is input from the edge line ID generation counter 405, and the drawing judgment circuit 410
When a remaining edge line drawing ON signal is sent from , the shape data memory 402 is accessed to obtain the projected positions of the vertices at both ends of the edge line, and a line segment connecting them is drawn.

Reference numeral 412 denotes a crossing edge line drawing circuit, into which the edge line ID is input from the edge line ID generation counter 405, and the drawing judgment circuit 410
When an intersecting edge line drawing ON signal is sent from , the shape data memory 402 is accessed to obtain the projected position of the vertex on the remaining side of the edge line, and the edge line determination circuit 403 is further accessed to determine the projected position of the intersection point. and draw a line segment connecting the two.

Reference numeral 413 denotes an edge line drawing memory, which inputs the edge line ID from the edge line ID generation counter 405 and outputs the remaining edge line drawing circuit 411.
Then, the projected positions of both end points of the edge drawn in the intersecting edge drawing circuit 412 are inputted and stored for each edge ID.

414 is an edge line erasing circuit, and the edge line ID generation counter 4
When the edge line ID is input from 05 and an erase-on signal is sent from the drawing determination circuit 410, the edge drawing edge memory 413 is accessed and the projection position of both end points of the edge line that has already been drawn on the screen is calculated. and erase the edge from the screen.

415 is an intersection line drawing circuit, and intersection edge line matching circuit 4
The edge line determination means 403 is accessed based on the corresponding intersecting edge ID set data output from 04 to obtain the projected position of the intersection of each intersecting edge line, and a line segment connecting the two is drawn.

Reference numeral 416 denotes an intersection line drawing memory, which inputs and sequentially stores the projected positions of both end points of the intersection line drawn in the intersection line drawing circuit 415.

An intersection line erasing circuit 417 accesses the intersection line drawing memory 416 to obtain the projected positions of both end points of the intersection lines already drawn on the screen, and erases all the intersection lines from the screen.

418 is a remaining edge line drawing circuit 411. Intersecting edge drawing circuit 4
12. Edge line erasure circuit 414. Intersection line drawing circuit 415. This is a display screen that displays line segments that can be drawn or erased by the intersection line erasing circuit 417.

In the three-dimensional shape display device having the above-described similar configuration, the operation of updating and displaying a polyhedral-shaped cut-and-removed image will be described.

(1) All edges in order from the edge ID generation counter 406!
lID is generated, and the value of the edge crossing state in the edge crossing state memory 407 is transferred to the old edge crossing state memory 409 via the data transfer circuit 408.

This allows the edge line intersection state from one screen ago to be saved in the edge line old intersection state memory 409.

(2) New plane parameters are input into the plane parameter input circuit 401.

(3) The edge line determination circuit 403 calculates the intersection state of each edge line of the polyhedron by the new plane, and stores the intersection state in the edge line intersection state memory 4.
Output on 07. The projected position of the intersection is also calculated and stored.

(4) The intersecting edge matching circuit 404 calculates and stores a set of corresponding intersecting edges.

(5) Edge line IDs are generated in order from the edge line ID generation counter 405.

(6) Edge line intersection state memory 407 and edge line old intersection state memory 409 for the edge line with the edge ID that occurred in (5)
The values of the current intersecting state and the intersecting state of one screen before are sent to the drawing determination circuit 410.

(7) The drawing determination circuit 410 determines whether or not to perform erasure processing and drawing processing for the edge line based on data on the intersecting state of the edge line, and outputs an erasure on/off signal, a remaining edge drawing on/off signal, and an intersecting edge drawing on/off signal. Occur. Note that the determination process is implemented in a logic circuit according to the logic shown in the table below.

(8) When the drawing determination circuit 410 outputs an erase-on signal, the edge line erase circuit 414 selects the edge line ID.
Based on the edge line ID determined by the generation counter 405, the edge line drawing memory 413 is accessed to erase the corresponding edge line one screen before from the display screen 418.

(9) When the remaining edge drawing ON signal is output from the drawing determination circuit 410, the remaining edge drawing circuit 411 calculates the projected position of the vertices at both ends of the edge based on the edge ID by the edge ID generation counter 405. Input from shape data memory 402 and write to edge line drawing memory 413,
A line segment connecting them is drawn on the display screen 418.

(10) When the intersecting edge drawing ON signal is output from the drawing determination circuit 410, the intersecting edge drawing circuit 411 determines the projected position of the apex of one end of the ridgeline and the intersection point based on the ridgeline ID by the ridgeline ID generation counter 405. is input from the shape data memory 402 and the edge line determination circuit 403, written into the edge line drawing memory 413, and a line segment connecting them is drawn on the display screen 418.

(11) The intersection line erasing circuit 417 accesses the intersection line drawing memory 416 and erases all the intersection lines one screen before from the display screen 418.

(12) The intersecting line drawing circuit 415 is the intersecting edge line matching circuit 4
04, a set of edge line IDs of intersecting edges located at both ends of each intersection line between a plane and a polyhedral surface is input, and the edge line determining means 40
3 to obtain the intersection projection position which should be the end point of the intersection line, write it into the intersection line drawing memory 416, and draw the line segment connecting it on the display screen 418.

(Effects of the Invention) As is clear from the above description, according to the present invention, in the continuous display of images cut and removed by planes of a polyhedron,
Since the drawing and erasing processes are omitted for edges that do not change on display, it is possible to reduce the display time even when the number of edges of a polyhedron increases, and it is possible to create a cut-and-remove image in which the cut plane gradually moves. Animation display is possible. Furthermore, such a function makes it possible to continuously move and position the plane in three-dimensional space while viewing the cutting/removal display on the screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of the present invention, FIG. 2 is a diagram showing the concept of display performed by a conventional three-dimensional shape display device when cutting a polyhedral shape by a plane, and FIG. FIG. 4 is a diagram showing the concept of display performed in the present invention when the cutting plane changes, and is a circuit block diagram showing an embodiment of the present invention.

Claims (1)

[Scope of Claims] Shape data storage means for storing shape data of a polyhedron; Plane parameter input means for inputting plane parameters of a plane cutting the polyhedron; Contents of the shape data storage means and the plane parameter input means. Intersection data generation means for generating intersection data between a polyhedron shape and a plane from the output; intersection data storage means for storing the output of the intersection data generation means; and a plane of each polyhedron edge among the outputs of the intersection data generation means. ridgeline crossing state storage means for storing the crossing state of the ridgeline crossing state; transfer means for saving and transferring the contents of the ridgeline crossing state storage means each time new crossing state data is output from the crossing data generation means; an edge line old intersection state storage means for storing the intersection state of each edge line of the polyhedron; the contents of the edge line intersection state storage means and the contents of the edge line old intersection state storage means are compared to display and erase each edge line of the polyhedron; a determining means for determining whether or not to perform each of the processes; A three-dimensional shape display device comprising shape display means for displaying a line drawing of an image that has been cut and removed.