JPH06314317A - Stereoscopic diagram drawing method for cad data - Google Patents

Abstract

PURPOSE:To quickly draw a stereoscopic diagram of the sheet metal CAD data. CONSTITUTION:This drawing method includes a 1st step 101 where the original three-dimensional CAD data is turned to acquire the desired three-dimensional CAD data a prescribed point of view and the least distance of each of faces forming the turned desired three-dimensional CAD data are compared with each other through the projecting screen where those faces are projected to rearrange the faces in the order of smaller distances, a 2nd step 102 where the master-slave relation is acquired among the faces to the projecting screen and then the order rearranged in the step 101 is rearranged again, and a 3rd step 103 where the inner and outer lines are drawn for the projected graphics of the faces to the projecting screen in the order rearranged in the step 102 and then the inside of the outer line and the outside of the inner line of each projected graphic of the faces are painted out in a prescribed color and pattern based on the normal vector value of the face corresponding to the projected graphic and superscribed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drawing a three-dimensional drawing for CAD data for drawing a three-dimensional drawing with hidden surface processing based on three-dimensional CAD data created in a sheet metal CAD / CAM system. In particular, the present invention relates to a method of drawing a three-dimensional diagram for CAD data in a CAD / CAM system using a personal computer.

[0002]

2. Description of the Related Art Conventionally, a computer-aided design (CAD: Computer-Aided Design) is performed, and a computer is used based on the design result (CAM: Comp-Aided Design).
A CAD / CAM system for performing uter-Aided Manufacturing is known.

That is, CAD is drawing data (CAD data) on a display with the support of a computer.
Is created, and the created CAD data is output to a storage device or the like. Then, the CAM interlocks with the CAD, creates an NC tape for automatic machining with a numerical control (NC) machine tool based on the CAD data output by the CAD, or sends the machining data directly to the machine tool. Direct manufacturing. This C
AD is easier to correct than drawing by hand and the created CAD data can be stored in a storage device. Therefore, it can be taken out at any time and used effectively in the past. As compared with manual work, there is no need to be proficient in drawing tools, which has the advantage of being able to train workers in a short period of time.

By the way, CAD created by CAD
In the data creation process, first, a plane creation process for creating CAD data for one plane is performed, then a surface synthesis process for three-dimensionally synthesizing the created CAD data for a plurality of planes is performed, and finally the CAD data that is synthesized is created. A two-dimensional expansion process is performed and the final CAD data is output to the CAM. Then, this surface-synthesized CAD
While changing the viewpoint, the data was drawn on a three-dimensional view to check the shape.

Further, since the sheet metal CAD / CAM system is a relatively simple object to be handled, it is often processed by using a personal computer or the like.

For this reason, when drawing a three-dimensional diagram with different viewpoints and confirming the final CAD data shape, etc.,
Since it is a personal computer, its physical processing speed is slow, and wire-frame display in which the hidden line processing is not performed on a stereoscopic drawing to be drawn is common.

According to the wire frame display without the hidden line processing, if it is not possible to know whether or not a surface is actually surrounded by a line, or if the number of lines is large, There was a problem that it was difficult to know where the surface existed.

On the other hand, there is known a method of performing a hidden surface processing on three-dimensional CAD data to draw a stereoscopic drawing (Atsumi Imamiya, hidden surface removal algorithm, Journal of Information Processing Society, Vol.
24, No. 4, Apr. 1983. p539-546).

A typical example of this hidden surface removal processing is a depth sorting method in which all the target surfaces are sorted in the order of depth, and the depth coordinate is set to Z for all pixels forming the surface.
There is a Z-buffer method in which a buffer is used for processing.

In the former depth sorting method, the target C
When the number of surfaces of AD data is small, the hidden surface removal processing can be performed in a short processing time. However, as the number of surfaces increases, the sorting processing becomes complicated and time-consuming.

Further, in the latter Z buffer method, even if the number of surfaces of the target CAD data increases, the hidden surface erasing processing can be performed in a substantially constant processing time because the processing is performed in pixel units. However, there is a problem that a certain amount of processing time is required even if the number of surfaces is small, and that if the number of pixels is large, the memory amount of the Z buffer becomes enormous.

Regarding the latter hidden surface erasing processing by the Z buffer method, there are JP-A-60-128574, JP-A-60-198690, and JP-A-61-161.
No. 241882, JP-A No. 62-42280,
JP-A-62-42281, JP-A-63-2238
No. 86, No. 1-112472, No. 1
-140384, JP-A-1-207886, JP-A-1-223580, and JP-A-2-734.
79, JP-A-2-163886, and JP-A-2-307172.

On the other hand, the CAD by the former depth sorting method
There is nothing related to the hidden surface erasing process of data, and it has not been adopted particularly for a sheet metal CAD / CAM system using a personal computer whose object is relatively simple. When CAD data is created by this personal computer or the like, the Z buffer method that can perform hidden surface removal processing in a fixed processing time even if it takes some time is adopted as the processing time increases as the number of processing surfaces increases. This is because it is more advantageous than the depth sorting method, which requires a huge amount of.

As for the hidden line processing, for example, JP-A-1-106176 or JP-A-1-106176.
There is a Japanese Patent No. 136279.

In addition, sheet metal CAD / CAM system CA
As a method of drawing a three-dimensional diagram for D data, for example, Japanese Patent Application Laid-Open No. 55-116160 describes a three-dimensional figure processing method for a figure of a sheet metal construct drawn based on the two-dimensional three-angle method. There is. Furthermore, JP-A-6
Japanese Patent Laid-Open No. 3-165970 describes a method for creating a mold model. Also, JP-A-62-2105
Japanese Patent No. 80 describes a method for creating a surface model of a sheet metal part.

Further, Japanese Patent Laid-Open No. 2-103687 describes a method of drawing a three-dimensional figure by the B-Rep method (Boudary Representation).

[0017]

As described above, a final CA is drawn by drawing a three-dimensional view from a different viewpoint on CAD data created using a personal computer.
When checking the shape of D data, etc., the physical processing speed is slow because it is a personal computer.
The three-dimensional drawing to be drawn was generally a wireframe display without hidden line processing. For this reason, it is not possible to know whether or not a surface actually exists in the area surrounded by the line, and if the number of lines increases due to the increase of the surface, which surface actually exists. The problem was that it was difficult to know.

On the other hand, in the CAD / CAM system using a personal computer, a hidden surface erasing process is performed by the Z buffer method in the CAD data drawing method for CAD data to draw a CAD data stereoscopic drawing. it was thought.

However, since the hidden surface erasing process by the Z buffer method is performed on a pixel-by-pixel basis, the sheet metal CA is used.
There is a problem in that a fixed processing time is required even for a relatively simple figure such as D data, and rapid drawing processing of a stereoscopic drawing by CAD data cannot be performed.

Therefore, the present invention eliminates the above problems,
It is an object of the present invention to provide a stereoscopic drawing method for CAD data that can quickly draw a stereoscopic drawing of CAD data based on the depth sorting method.

[0021]

The present invention is a CAD / CA system.
Two-dimensional C composed of linear elements created by M system
In a CAD data three-dimensional drawing drawing method for drawing a three-dimensional CAD data three-dimensional drawing based on AD data and bending information, the three-dimensional CAD data is rotated to obtain desired three-dimensional CAD data from a predetermined viewpoint. , Comparing the minimum distance of each of the plurality of surfaces from a projection surface projecting the plurality of surfaces forming the desired three-dimensional CAD data after the rotation, and rearranging the plurality of surfaces in ascending order of the minimum distance. A first step, a second step of obtaining a vertical relationship of the plurality of surfaces with respect to the projection plane, and rearranging the order rearranged in the first step based on the vertical relationship, and a rearrangement by the second step. Drawing the inside and outside lines of the projection figure of the plurality of surfaces with respect to the projection plane, and the inside of the outside line of the projection figure and the outside of the inside line of the projection figure corresponding to the projection figure. Filled with a predetermined color and pattern on the basis of the value of the normal vector, characterized by comprising a third step of overwriting.

In the present invention, the second step is
The maximum distance is equal to or less than the minimum distance by comparing the maximum distance of the first surface from the predetermined projection surface of the plurality of surfaces and the minimum distance of the second surface from the predetermined projection surface. If the maximum distance is not less than or equal to the minimum distance in the first step, a line of intersection between the infinite plane of the first surface and the infinite plane of the second surface is determined. A second step of determining whether or not at least one of the projected figure of the first surface and the projected figure of the second surface is a one-sided projected figure that does not overlap the intersection line;
If there is a one-sided projected figure in the step, a third step of determining whether or not one one-sided projected figure and another projected figure including a case of another one-sided projected figure have a overlapping portion, When there is an overlapping portion in the third step, a point on the surface corresponding to the one-sided projected figure corresponding to the overlapping portion, a straight line passing through the point and parallel to the viewpoint direction, and the other projected figure Find the intersection with the surface corresponding to
A fourth step of comparing the distance from the predetermined projection plane to the point with the distance from the predetermined projection plane to the intersection, and determining whether or not the distance to the point is larger; If it is determined in one step that the maximum distance of the first surface is less than or equal to the minimum distance of the second surface, then the first
Is determined to be below the second surface, and when it is determined that the distance to the point is larger in the fourth step, the surface corresponding to the one one-side projected figure is the other surface. If it is determined that the distance to the point is not larger in the fourth step, the surface corresponding to the one one-sided projected figure is Fifth, which is determined to be below the plane corresponding to the projected figure of
And a step.

[0023]

According to the present invention, when a three-dimensional drawing of three-dimensional CAD data is drawn based on two-dimensional CAD data and bending information composed of linear elements created by the CAD / CAM system, first of all, in the first step, Desired 3 from a given viewpoint
The three-dimensional CAD data is rotated to be three-dimensional CAD data, and the respective minimum distances of the plurality of surfaces from the projection plane projecting the plurality of surfaces forming the desired three-dimensional CAD data after the rotation are compared. Then, the plurality of surfaces are rearranged in the ascending order of the minimum distance. Then, in the second step, the vertical relationship of the plurality of surfaces with respect to the projection plane is obtained, and the order rearranged in the first step is rearranged based on the vertical relationship. Finally, in a third step, the inner and outer lines of the projection figure of the plurality of surfaces with respect to the projection plane are drawn in the order rearranged in the second step, and the inside of the outer line of the projection figure and the projection figure are drawn. The outside of the internal line is filled with a predetermined color / pattern based on the value of the normal vector of the surface corresponding to the projected figure, and the overwriting process is performed to perform the desired three-dimensional CA.
Draw a stereoscopic view of D data.

As a result, a three-dimensional figure in which the hidden surface removal processing of the desired three-dimensional CAD data is performed and a three-dimensional figure having a three-dimensional effect can be drawn by painting, so that each surface constituting the three-dimensional CAD data can be drawn. The positional relationship of can be easily and quickly grasped.

Further, according to the present invention, the processing of the second step is processed in the following steps. First, in a first step, the maximum distance is determined by comparing a maximum distance of a first surface of the plurality of surfaces from a predetermined projection surface and a minimum distance of a second surface of the plurality of surfaces from the predetermined projection surface. It is determined whether the distance is less than the minimum distance. Next, in the second step, the first
If the maximum distance is not less than or equal to the minimum distance in step, the line of intersection between the infinite plane of the first surface and the infinite plane of the second surface is obtained, and the projected figure of the first surface and the second plane are obtained. It is determined whether or not at least one of the projected figures on the surface is a one-sided projected figure that does not overlap the intersection line. Next, the third
In the step, if there is a one-sided projected figure in the second step, it is determined whether or not one one-sided projected figure and another projected figure including a case of another one-sided projected figure have an overlapping portion. . Next, in the fourth step, when there is an overlapping portion in the third step, a point on the surface corresponding to the one-sided projected figure corresponding to the overlapping portion and a point passing through the point in the viewpoint direction The intersection of a parallel straight line and the surface corresponding to the other projected figure is obtained, and the distance from the predetermined projection surface to the point is compared with the distance from the predetermined projection surface to the intersection, and the point Determine if the distance to is greater. Finally, as a fifth step, if it is determined in the first step that the maximum distance of the first surface is less than or equal to the minimum distance of the second surface, the first surface is set to the second distance. If it is determined that the distance to the point is larger in the fourth step,
When it is determined that the surface corresponding to the one one-sided projected figure is above the surface corresponding to the other projected figure, and it is determined that the distance to the point is not larger in the fourth step, It is determined that the surface corresponding to the one projection graphic is below the surface corresponding to the other projection graphic.

By such determination processing, three-dimensional CAD
It is possible to always quickly determine the vertical relationship of the plurality of surfaces that form the data.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a sheet metal CA which is an embodiment of the present invention.
It is a figure which shows the structure of a D / CAM system.

In FIG. 2, the sheet metal CAD / CAM system comprises a CPU 1 for controlling the whole, a memory 2, a display unit 3, a keyboard 4, a mouse 5, a floppy disk device 6 and a hard disk device 7.

When performing sheet metal CAD / CAM processing, an application for sheet metal CAD / CAM processing stored in the hard disk device 7 is read into the memory 2 by a predetermined input instruction from the keyboard 4 or the mouse 5. Then, under the control of the CPU 1, this application is displayed on the display unit 3, and the process is executed by the user inputting an instruction from the keyboard 4 or the mouse 5 to the displayed application. Then, when the processing of the CAD data is completed, the processing result is output and stored in the hard disk device 7. After that, CAM processing is executed based on this CAD data, processed data is created, and the floppy disk device 6
The processed data created on the floppy disk will be stored.

In the sheet metal CAD / CAM system as described above, the CAD data creating process first performs a plane creating process for creating CAD data of one plane, and the created CAD data of a plurality of planes is three-dimensionally processed. The surface synthesizing process for synthesizing the CAD data is performed, the developing process for finally synthesizing the CAD data in two dimensions is performed, and the final CAD data is output. A three-dimensional CAD data stereoscopic drawing drawing method in this surface synthesis processing will be described below.

FIG. 1 is an overall flow chart showing a procedure for drawing a three-dimensional diagram which is an embodiment of the present invention.

Here, the object of the method for drawing a three-dimensional drawing according to the present invention relates to the sheet metal CAD / CAM, and the surface to be drawn is composed of only straight lines, and the straight lines such as arcs are previously set. It is converted by a group of minute lines.
Also, when drawing a three-dimensional diagram, XYZ coordinates are used, the XY coordinate plane is the projection plane of the target CAD data, and the viewpoint is + ∞ (infinity) of the Z coordinate. Further, basically, the drawing procedure of the stereoscopic diagram is performed based on the depth sorting method.

The symbols used at the time of explanation have the following meanings. That is, A: minimum value of Z coordinate of three-dimensional surface (S) B: maximum value of Z coordinate of three-dimensional surface (S) I: 3 when the three-dimensional surface (S) is considered as an infinite plane Dimensional surface M: Z component of the normal vector of the three-dimensional surface (S) P: Point on the three-dimensional surface (S) S: Three-dimensional surface T: Two-dimensional surface projected on the XY coordinate plane Surface Z: Z coordinate value of P a: attached to the above I to Z, meaning all of a plurality i: attached to the above I to Z, meaning one of a plurality j: I above It is attached to Z and means one of a plurality.

Now, in FIG. 1, the target surface (S
Sort with a) as the initial state (step 10)
1). That is, the surface Sa is sorted in the ascending order of the minimum value Aa based on the minimum value Aa of the Z coordinate values of the vertices forming the surface Sa.

Next, the surface S sorted in step 101
The order of the initial state of a is rearranged in the drawing order (step 102). That is, using the surface Sa as a unit, the vertical relationship of overlapping surfaces when viewed from the viewpoint is obtained, and the surface Sa is sorted in the order of increasing distance from the viewpoint based on the vertical relationship of the surfaces.

Finally, the surface Sa is drawn on the projection surface (XY surface) in the order sorted in step 102 (step 103).

Therefore, when each surface Sa is viewed from the viewpoint, if there is no overlapping surface, the drawing processing of step 103 is performed in the order of the initial state of step 101, and consequently the hidden surface removal processing is not performed. Then, when looking at each surface Sa from the viewpoint, if there is a set of overlapping surfaces, the sorting processing of step 102 is performed for each set of the surfaces, and the hidden surface removal processing is performed for each set of the surfaces. It will be.

Next, each step of FIG. 1 will be described in detail.

FIG. 3 is a detailed flowchart of the initial rearrangement process in step 101 of FIG.

In FIG. 3, first, three-dimensional CAD data is created from the target two-dimensional surface data and bending information (step 201). Then, since the viewpoint is + ∞ of the fixed Z coordinate, the rotation processing is performed so that the desired projection plane for this three-dimensional CAD data becomes the XY plane (step 202). A plurality of surface data forming the three-dimensional data after the rotation processing in step 202 is the surface S
is a. Then, processing for connecting the surface Sa to the chain is performed (step 203). The order of connecting the chains in step 203 is arbitrary and is not specified.

The initial values of the variables i and j are i =
1, j = 2 (step 204). Where i and
The value of j is also a value indicating the order of chains. Therefore,
The surface Si indicates the i-th surface S of the chain. Now, after that, it is judged whether or not the minimum value Zi of the Z coordinate of the surface Si is larger than the minimum value Zj of the Z coordinate of the surface Sj (step 20).
5) If it is larger, after changing the order of Si and Sj of the chain created in step 203 (step 20)
6) The procedure moves to step 207, and if not larger, the procedure moves directly to step 207.

In step 207, it is judged whether or not the processing for all i and j has been completed. If not completed, the values of i and j are updated (step 208), and step 2
The procedure shifts to 05 and the above processing is repeated. On the other hand, step 2
If the processing for all i and j is completed in 07,
This process ends.

In this way, the CAD data is rotated so that the surface forming the target CAD data becomes a stereoscopic view from the viewpoint of + ∞ of the Z coordinate, and the minimum value Aa of the Z coordinate for each surface Sa is calculated. Create a sorted initial chain.

Next, the processing of step 102 in FIG. 1 will be described in detail.

FIG. 4 is a detailed flowchart of the process of rearranging the drawing order in step 102 of FIG.

In FIG. 4, first, i and j are initialized to i =
1, j = 2 is set (step 301). Here, the values of i and j are values indicating the order of chains as described above.

Then, a process for checking the vertical relationship between the surfaces Si and Sj created in step 101 of FIG. 1 is performed (step 302). The details of the process of step 302 will be described later. Then, as a result of step 302, it is determined whether or not the surface Si is on the surface Sj (step 303), and when the surface Si is on the surface Sj, a process of exchanging the surface Si and the surface Sj is performed. After (Step 30
4) and shifts to step 305. On the other hand, when the surface Si is not on the surface Sj, the process directly proceeds to step 305.

Then, in step 305, it is determined whether or not the processing for all i and j is completed, and if all the processing is completed, i and j are updated (step 30
6) The procedure moves to step 302 and the above processing is repeated.
On the other hand, when the processing for all i and j is completed in step 305, this processing is completed.

In this way, the vertical relationship of the surfaces Sa is checked, and based on this vertical relationship, the final sorting in the drawing order is performed.

Next, the processing of step 103 in FIG. 1 will be described in detail.

FIG. 5 is a detailed flowchart of the stereoscopic drawing processing in step 103 of FIG.

In FIG. 5, first, the variable i is set to i as an initial value.
= 1 is set (step 401). Where the variable i
Is the order of the chains created in step 102. Next, the inner and outer lines of the two-dimensional surface Ti projected on the XY plane of the surface Si are drawn (step 402). After that, the outside of the internal line of the surface Ti and the inside of the external line of the surface Ti are filled with different colors based on the Z component Mi of the normal vector of the surface Si (step 403). That is, when viewed from the viewpoint, the surface that is the front surface side and the surface that is the back surface side of the three-dimensional shape of the target CAD data are filled with different colors.

Then, it is determined whether or not the next surface S exists based on the chain created in step 102 (step 404). If the next surface S exists, the variable i is set to i +
The value is set to 1 (step 405), the process proceeds to step 402, and the above process is repeated. On the other hand, in step 404, if the next surface S does not exist, this processing ends.

As a result, the projected figure of the surface Sa which constitutes the target CAD data is filled with a different color depending on whether it is the front side or the back side of the three-dimensional shape, and the three-dimensional drawing is overwritten sequentially from the surface far from the viewpoint. Will be drawn.
Then, the hidden surface removal processing is performed by this overwriting.

Next, the process of checking the vertical relationship of the surfaces in step 302 of FIG. 4 will be described in detail.

FIGS. 6 to 9 are detailed flowcharts of the processing for checking the vertical relationship of the surface S in step 302 of FIG.

Further, FIGS. 10 to 15 are views for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

First, in FIG. 6, it is determined whether or not the maximum value Bi of the Z coordinate of the surface Si is less than or equal to the minimum value Aj of the Z coordinate of the surface Sj (step 501). And the maximum value Bi
Is smaller than the minimum value Aj, it is determined that the surface Si is located below the surface Sj (step 502).

On the other hand, in step 501, the maximum value B
If i is not less than the minimum value Aj, it is further determined whether or not the surface Si and the surface Sj are parallel to each other (step 503). Then, when the surface Si and the surface Sj are parallel to each other, the process proceeds to step 521 in FIG.

In step 521, first, it is determined whether or not the two-dimensional surface Ti obtained by projecting the surface Si on the XY plane and the two-dimensional surface Tj obtained by projecting the surface Sj on the XY plane overlap. If they do not overlap, it is determined that the vertical relationship between the surface Si and the surface Sj is indefinite (step 524). On the other hand, in the case of overlapping (FIG. 10A), the intersection of a straight line L1 that passes through the point Pi on the surface Si and is parallel to the Z axis and the three-dimensional surface Ij when the surface Sj is considered to be an infinite plane. Pj is obtained (step 522, FIG. 10B). Therefore, the projections of the point Pi and the intersection point Pj on the XY plane are the plane Ti and the plane Tj.
It is located in the overlapping part of. The same applies to Pi and Pj described later.

The Z coordinate value Zi of the point Pi is Z of the point Pj.
It is determined whether or not the coordinate value is larger than Zj (step 52).
3). If it is determined that the coordinate value Zi is large, it is determined that the surface Si is located on the surface Sj (step 525). If it is determined that the coordinate value Zi is not large, the surface Si is the surface Sj of the surface Sj. It is determined to be located below (step 526).

Now, in step 503 of FIG. 6, when the surface Si and the surface Sj are not parallel, when the surface Si is considered as an infinite plane, and when the three-dimensional surface Ii and surface Sj are considered as infinite planes. A straight line L obtained by projecting a line of intersection with the three-dimensional surface Ij on the XY plane is obtained (step 504). And surface S
It is determined whether both the two-dimensional surface Ti obtained by projecting i on the XY plane and the two-dimensional surface Tj obtained by projecting the surface Sj on the XY plane are on one side of the straight line L, that is, do not overlap with the straight line L. However, if they do not overlap each other (step 505), it is further determined whether or not both the surface Ti and the surface Tj are on the same surface side of the surfaces separated by the straight line L (step 506). Then, when the surface Ti and the surface Tj are not on the same surface side, it is determined that the vertical relationship between the surface Si and the surface Sj is indefinite (step 507, FIG. 12), and the surface Ti and the surface Tj are the same surface. If it is on the side (FIG. 11A), the process further proceeds to step 531 of FIG.

In step 531 of FIG. 8, first, it is determined whether or not the surface Ti and the surface Tj overlap each other. If they do not overlap, it is determined that the vertical relationship between the surface Si and the surface Sj is indefinite ( Step 534). On the other hand, if they overlap (Fig. 11
(A)) Further, the intersection point Pj between the straight line L2 passing through the point Pi on the surface Si which is not on the straight line L and parallel to the Z axis and the three-dimensional surface Ij when the surface Sj is considered to be an infinite plane is obtained. (Step 53
2, FIG. 11 (b)).

Then, the Z coordinate value Zi of the point Pi is Z of the point Pj.
It is determined whether the coordinate value is larger than Zj (step 53).
3). If it is determined that the coordinate value Zi is large, it is determined that the surface Si is located on the surface Sj (step 535). If it is determined that the coordinate value Zi is not large, the surface Si is the surface Sj of the surface Sj. It is determined to be located below (step 536).

In step 505 of FIG. 6, if at least one of the surface Ti and the surface Tj overlaps the straight line L, it is further determined whether or not the surface Ti does not overlap the straight line L ( If the surface Ti does not overlap the straight line L (step 508) (FIG. 13A), as in the case where the surface Ti and the surface Tj are on the same surface side in step 506,
Processing for checking the vertical relationship is performed based on the flowchart of FIG. 8 (FIG. 13B).

That is, in step 531 of FIG. 8, it is determined whether or not the surface Ti and the surface Tj overlap. If they do not overlap, it is determined that the vertical relationship between the surface Si and the surface Sj is indeterminate ( Step 534). On the other hand, if they overlap (Fig. 1
3 (a) is the intersection point Pj between the straight line L3 passing through the point Pi on the surface Si that is not on the straight line L and parallel to the Z axis, and the three-dimensional surface Ij when the surface Sj is considered to be an infinite plane. Ask (Step 5)
32, FIG. 13B).

Then, the Z coordinate value Zi of the point Pi is Z of the point Pj.
It is determined whether the coordinate value is larger than Zj (step 53).
3). If it is determined that the coordinate value Zi is large, it is determined that the surface Si is located on the surface Sj (step 535). If it is determined that the coordinate value Zi is not large, the surface Si is the surface Sj of the surface Sj. It is determined to be located below (step 536).

On the other hand, when the surface Ti overlaps the straight line L in step 508 (FIG. 14A), it is further determined whether or not the surface Tj overlaps the straight line L (step 509). , If both of the surfaces Ti and Tj overlap the straight line L, the surface Si
Is determined to be indefinite (step 510, FIG. 15). On the other hand, when the surface Tj does not overlap the straight line L (FIG. 14A), step 54 in FIG.
Move to 1.

In step 541 of FIG. 9, first, it is determined whether or not the surface Ti and the surface Tj overlap. If they do not overlap, it is determined that the vertical relationship between the surface Si and the surface Sj is indeterminate ( Step 544). On the other hand, if they overlap (Fig.
(A)) Further, the intersection point Pi between the straight line L4 that passes through the point Pj on the surface Sj that is not on the straight line L and is parallel to the Z axis and the three-dimensional surface Ii when the surface Ti is considered as an infinite plane is obtained. (Step 54
2, FIG. 14 (b)).

Then, the Z coordinate value Zi of the point Pi is Z
It is determined whether or not the coordinate value is larger than Zj (step 54).
3). If it is determined that the coordinate value Zi is large, it is determined that the surface Si is located on the surface Sj (step 545). If it is determined that the coordinate value Zi is not large, the surface Si is the surface Sj of the surface Sj. It is determined to be located below (step 546).

In this way, the vertical relationship between the surfaces Si and Sj can be easily obtained.

Next, the entire processing will be described based on a specific example of CAD data.

FIG. 16 is a diagram showing concrete CAD data. Then, FIG. 16A shows step 20 of FIG.
1 is a diagram showing three-dimensional data created by the method shown in FIG.
6B is a diagram showing a two-dimensional projection view of the three-dimensional data after rotation, which is created in step 202 of FIG. 3, on the XY plane.

In FIG. 16 (a), the three-dimensional CAD data to be created includes bottom surface S1, front surface S2, right side surface S3,
It is composed of a rear surface S4 and a left side surface S5. And
The front surface S2 has a punched surface SI2 inside the surface, and the right side surface S3
Has a punched surface SI3 inside the surface, the rear surface S4 has a punched surface SI4 inside the surface, and the left side surface has a punched surface SI4 inside the surface.
Have five. Drawing of a stereoscopic view of three-dimensional CAD data composed of five surfaces without such an upper surface is processed as follows.

First, in step 202 of FIG. 3, the viewpoint of infinity in the Z direction is set as shown in FIG. 16A so as to correspond to the case where the three-dimensional CAD data is viewed from a desired direction. Fix and rotate 3D CAD data. As a result, the same processing as when the desired viewpoint is moved relatively is performed. And FIG. 16 (b) shows
This is a two-dimensional figure projected on the XY plane with respect to the three-dimensional CAD data that has been rotated as desired.

FIG. 17 is a diagram showing changes in the chain state.

First, FIG. 17A shows a chain of the surfaces S1 to S5 created in step 203, and the connecting order of this chain is arbitrary. Here, the surface S1
To S5 in this order.

Next, in FIG. 17B, steps 204 to 2 are executed.
8 shows the final chain state created by No. 08, and the surfaces are connected in ascending order of the minimum value A based on the minimum value A of the Z coordinates of the surfaces S1 to S5. Here, the surface S2
Is rearranged at the end of the chain because it is closest to the viewpoint. As a result, the initial chain in step 101 of FIG. 1 is created.

Next, FIG. 17C shows step 10 of FIG.
2 shows the chain state rearranged, and the rearrangement is performed based on the vertical relationship of the surfaces S1 to S5 examined in step 302 of FIG. For example, first, the vertical relationship between the surface S1 and the surface S3 is checked by FIG. 17B, the surface S1 is determined to be below the surface S3, and the chains are not replaced. Next, the vertical relationship between the surfaces S1 and S4 is examined, it is determined that the vertical relationship between the surfaces S1 and S4 is indefinite, and the chains are not replaced. In this way, when the chains are exchanged on the basis of the vertical relation of all the surfaces, the surface S3 and the surface S4 are finally exchanged into a chain state. The order of this chain is the order farther from the viewpoint when each surface overlaps, and this order is the order to draw.

Next, FIG. 18 is a diagram showing a drawing state of a three-dimensional drawing in step 103 of FIG.

In FIG. 18, first, the projection plane T1 of the first surface S1 of the chain of FIG. 17C onto the XY plane is taken out and the inner and outer lines are drawn. In this case, since there is no punched surface, only the outside line is used. Then, since the Z component M1 of the normal vector of the surface S1 is negative, it is painted in a color showing the inside. Here, it is filled with a pattern showing the inside.
Next, the projection plane T4 of the plane S4 onto the XY plane is taken out from the chain order of FIG. Also in this case, since the Z component M4 of the normal vector of the surface S4 is negative, it is filled with a pattern showing the inside. This fill is processed on the outside of the internal line and the inside of the external line. Next, the projection surface T3 of the surface S3 onto the XY plane is taken out and the inside and outside lines are drawn. In this case, since the Z component M3 of the normal vector of the surface S3 is positive, it is filled with a pattern showing the outside. And in this case, it is overwritten.
Similarly, the inner and outer lines of the projection plane T5 corresponding to the order of the chains are drawn and overwritten (FIG. 18D), and finally the inner and outer lines of the projection surface T2 are drawn and filled. , The overwritten solid view is drawn (FIG. 18 (e)).

As described above, in the present embodiment, the advantage of the depth sorting method that can perform a quick sorting process,
The three-dimensional view of the created CAD data (FIG. 18 (e)) is subjected to hidden surface removal processing, and whether the displayed surface is front or back is displayed by utilizing the characteristics of the sheet metal CAD data. Therefore, the created CAD data can be drawn as a stereoscopic view that is easy to understand. Especially, sheet metal C
In the case of AD data, since the punching surface exists, the inner surface can be seen from this punching surface, which makes it easier to visually grasp as a three-dimensional diagram. In addition, as described above, the simple depth sorting method that makes use of the characteristics of the sheet metal CAD data makes it possible to draw solid views from various viewpoints quickly and continuously.

[0084]

As described above, according to the present invention, CA
3D CA based on 2D CAD data and bending information composed of linear elements created by the D / CAM system
When drawing a stereoscopic view of D data, first, in the first step,
The three-dimensional CAD data is rotated so as to obtain the desired three-dimensional CAD data from a predetermined viewpoint, and the plurality of surfaces forming the desired three-dimensional CAD data after the rotation are projected from the projection surface to the plurality of surfaces. The respective minimum distances are compared and the plurality of surfaces are rearranged in the ascending order of the minimum distance. Then, in the second step, the vertical relationship of the plurality of surfaces with respect to the projection plane is obtained, and the order rearranged in the first step is rearranged based on the vertical relationship. Finally, in a third step, the inner and outer lines of the projection figure of the plurality of surfaces with respect to the projection plane are drawn in the order rearranged in the second step, and the inside of the outer line of the projection figure and the projection figure are drawn. The outside of the internal line is filled with a predetermined color / pattern based on the value of the normal vector of the surface corresponding to the projected figure, and an overwriting process is performed to draw the three-dimensional diagram of the desired three-dimensional CAD data.

Therefore, a three-dimensional figure in which the hidden surface removal processing of the desired three-dimensional CAD data is performed and a three-dimensional figure having a three-dimensional effect can be drawn by painting, and thus the three-dimensional figure can be drawn.
This has an advantage that the positional relationship between the surfaces forming the three-dimensional CAD data can be easily and quickly grasped.

Further, in the present invention, the processing of the second step is processed in the following steps. That is, first, in the first step, the maximum distance of the first surface of the plurality of surfaces from the predetermined projection surface is compared with the minimum distance of the second surface from the predetermined projection surface to determine the maximum distance. It is determined whether or not the distance is less than or equal to the minimum distance. Next, in the second step, if the maximum distance is not less than or equal to the minimum distance in the first step, an intersection line between the infinite plane of the first surface and the infinite plane of the second surface is obtained, and It is determined whether at least one of the projected figure of the first surface and the projected figure of the second surface is a one-sided projected figure that does not overlap the intersection line. Next, in the third step, if there is a one-sided projected figure in the second step, does one portion of the one-sided projected figure overlap with another projected figure including the case of another one-sided projected figure? Determine whether or not. Next, in the fourth step, if there is an overlapping part in the third step,
The point on the surface corresponding to the one-sided projected figure corresponding to the overlapping portion and the intersection point of the straight line passing through the point and parallel to the viewpoint direction and the surface corresponding to the other projected figure are obtained, and The distance from the predetermined projection plane to the point is compared with the distance from the predetermined projection plane to the intersection, and it is determined whether or not the distance to the point is larger. Finally, as a fifth step, if it is determined in the first step that the maximum distance of the first surface is less than or equal to the minimum distance of the second surface, the first surface is set to the second distance. Determined to be below the surface,
When it is determined that the distance to the point is larger in the fourth step, it is determined that the surface corresponding to the one projection graphic on one side is above the surface corresponding to the other projection graphic, When it is determined in the fourth step that the distance to the point is not larger, it is determined that the surface corresponding to the one one-sided projected figure is below the surface corresponding to the other projected figure.

Therefore, by using this determination processing, there is an advantage that it is possible to always quickly determine the vertical relationship of the plurality of surfaces forming the three-dimensional CAD data.

[Brief description of drawings]

FIG. 1 is an overall flowchart showing a drawing procedure of a stereoscopic diagram which is an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a sheet metal CAD / CAM system that is an embodiment of the present invention.

FIG. 3 is a flowchart showing detailed processing of step 101 in FIG.

FIG. 4 is a flowchart showing detailed processing of step 102 in FIG.

5 is a flowchart showing the detailed processing of step 103 in FIG.

FIG. 6 is a detailed flowchart of processing for checking the vertical relationship of the surface S in step 302 of FIG.

FIG. 7 is a detailed flowchart of processing for checking the vertical relationship of the surface S in step 302 of FIG.

FIG. 8 is a detailed flowchart of processing for checking the vertical relationship of the surface S in step 302 of FIG.

9 is a detailed flowchart of a process of checking the vertical relationship of the surface S in step 302 of FIG.

FIG. 10 is a diagram for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 11 is a diagram for explaining the process of checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 12 is a diagram for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 13 is a diagram for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 14 is a diagram for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 15 is a diagram for explaining the processing for checking the vertical relationship of the surfaces in step 302 of FIG.

FIG. 16 is a diagram showing specific CAD data.

FIG. 17 is a diagram showing a change in chain state.

FIG. 18 is a diagram showing a drawing state of a stereoscopic diagram in step 103 of FIG. 1;

[Explanation of symbols]

 1 CPU 2 Memory 3 Display 4 Keyboard 5 Mouse 6 Floppy Disk Device 7 Hard Disk Device B Bus

Claims (2)

[Claims] 1. A CAD data three-dimensional drawing method for drawing a three-dimensional CAD data three-dimensional drawing based on bending information and two-dimensional CAD data composed of linear elements created by a CAD / CAM system. Of the plurality of surfaces from the projection surface that rotates the three-dimensional CAD data so as to obtain the desired three-dimensional CAD data viewed from the viewpoint, and projects a plurality of surfaces forming the desired three-dimensional CAD data after the rotation. Comparing the respective minimum distances and rearranging the plurality of surfaces in ascending order of the minimum distances.
A step, a second step of obtaining a vertical relationship of the plurality of surfaces with respect to the projection surface, and rearranging the order rearranged in the first step based on the vertical relationship; and a rearrangement by the second step. In order, the inside and outside lines of the projection figure of the plurality of planes with respect to the projection plane are drawn, and the inside of the outside line of the projection figure and the outside of the extension line of the projection figure are the values of the normal vector of the plane corresponding to the projection figure. A CAD data three-dimensional drawing method, which comprises a third step of filling in a predetermined color and pattern based on the above and overwriting. 2. The second step compares a maximum distance of a first surface of the plurality of surfaces from a predetermined projection surface and a minimum distance of a second surface of the plurality of surfaces from the predetermined projection surface. A first step of determining whether the maximum distance is less than or equal to the minimum distance; and, if the maximum distance is not less than or equal to the minimum distance in the first step, an infinite plane of the first surface and the The line of intersection of the second surface with the infinite plane is determined, and whether or not at least one of the projected figure of the first surface and the projected figure of the second surface is a one-sided projected figure that does not overlap with the line of intersection is determined. Second to judge
When there is a one-sided projected figure in step 2 and the second step, it is determined whether or not one one-sided projected figure and another projected figure including the case of another one-sided projected figure have an overlapping portion. If there is a third step and a portion that overlaps in the third step, a point on the surface corresponding to the one-sided projected figure corresponding to the overlapping portion, and a straight line that passes through the point and is parallel to the viewpoint direction. And the intersection point with the surface corresponding to the other projected figure, and by comparing the distance from the predetermined projection surface to the point and the distance from the predetermined projection surface to the intersection point, the distance to the point Is larger than the second distance, and the maximum distance of the first surface is the second distance in the first step.
When it is determined that the distance is less than or equal to the minimum distance of the surface of the first surface, it is determined that the first surface is below the second surface, and it is determined that the distance to the point is larger in the fourth step. If it is determined that the surface corresponding to the one-sided projected figure is above the surface corresponding to the other projected figure, the fourth
If it is determined in step that the distance to the point is not larger, it is determined that the surface corresponding to the one one-side projected figure is below the surface corresponding to the other projected figure. The above-mentioned claim 1 characterized by comprising:
3D drawing method of CAD data described.