#312 analyze doesn't show NO PLANE for an improper rpp

open
nobody
Analysis (10)
5
2012-01-18
2012-01-18
Tom Browder
No

The attached g file has an rpp with one edge shortened to create a non-planar face. When analyze is run on it, the result is as if all faces were planar. the output follows:

rpp_skew.s: ARB8
1 (9, 0, 0)
2 (10, 10, 0)
3 (10, 10, 10)
4 (10, 0, 10)
5 (0, 0, 0)
6 (0, 10, 0)
7 (0, 10, 10)
8 (0, 0, 10)

------------------------------------------------------------------------------
| FACE | ROT FB | PLANE EQUATION | SURFACE AREA |
|------|---------------|----------------------------------|------------------|
| 1234 | 354.28940686 0.00000000 | 0.99503719 -0.09950372 0.00000000 8.95533471 | 100.49875621 |
| 5678 | 180.00000000 -0.00000000 | -1.00000000 -0.00000000 -0.00000000 -0.00000000 | 100.00000000 |
| 1584 | 270.00000000 -0.00000000 | -0.00000000 -1.00000000 -0.00000000 -0.00000000 | 95.00000000 |
| 2376 | 90.00000000 -0.00000000 | -0.00000000 1.00000000 -0.00000000 10.00000000 | 100.00000000 |
| 1265 | 0.00000000 -90.00000000 | -0.00000000 0.00000000 -1.00000000 -0.00000000 | 95.00000000 |
| 4378 | 0.00000000 90.00000000 | 0.00000000 -0.00000000 1.00000000 10.00000000 | 100.00000000 |
------------------------------------------------------------------------------
| EDGE LEN | EDGE LEN | EDGE LEN | EDGE LEN |
|----------------|----------------|----------------|----------------|
| 12 10.04987562 | 23 10.00000000 | 34 10.00000000 | 14 10.04987562 |
| 15 9.00000000 | 56 10.00000000 | 26 10.00000000 | 67 10.00000000 |
| 78 10.00000000 | 58 10.00000000 | 48 10.00000000 | 37 10.00000000 |
---------------------------------------------------------------------
| Volume = 966.66666667 Surface Area = 590.49875621 |
| 0.00025537 gal |
-----------------------------------------------------------------

Looking at the code it seems that only 3 face points are used to check for planarity, thus the test should never fail (unless 2 points are coincident). If the intent is to be robust, the code I guess is fine, but the man page should state that.

Discussion

  • Tom Browder

    Tom Browder - 2012-01-18

    g file with a non-planar rpp

     
  • John

    John - 2012-12-20

    For GCI effects, I managed to reproduce this bug with the same commands in
    the VM from BRL-CAD.

     

Log in to post a comment.