[brlcad-tracker] [ brlcad-Bugs-3013742 ] pipe with min bend radius crashes mged

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Bugs item #3013742, was opened at 2010-06-09 09:35
Message generated for change (Comment added) made by johnranderson
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Category: Geometry Conversion
Group: serious bug / workaround
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: Richard Uschold (gilliganu)
>Assigned to: John Anderson (johnranderson)
Summary: pipe with min bend radius crashes mged

Initial Comment:
A pipe with the bend radius set to exactly one half of the outside diameter causes the ev(aluate) command to crash mged.

pipe3.s crashes:
pipe3.s:  pipe with 3 points
	0 	bend radius = 0.1  od=0.2
	  at=(0, 0.3, 0.5)
	1 	bend radius = 0.1  od=0.2
	  at=(0, 0, 0.5)
	2 	bend radius = 0.1  od=0.2
	  at=(0, 0, 0)

for a work around, I made the bend radius to a bit larger:

pipe3a.s:  pipe with 3 points
	0 	bend radius = 0.1  od=0.2
	  at=(0, 0.3, 0.5)
	1 	bend radius = 0.100001  od=0.2
	  at=(0, 0, 0.5)
	2 	bend radius = 0.1  od=0.2
	  at=(0, 0, 0)

No doubt, this is a round off error where the bend radius becomes less than half of the od. This will cause the torus to intersect itself.

Gilligan

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>Comment By: John Anderson (johnranderson)
Date: 2010-06-20 17:30

Message:
tessellate_pipe_bend() was not able to handle cases where the bend radius
equals the outer radius of the pipe. The problem was that such a
situation
produces degenerate faces. The fix was to add a vertex tree and a vertex
array to help in identifying and skipping the degenerate faces.


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Comment By: John Anderson (johnranderson)
Date: 2010-06-20 17:30

Message:
This issue has been resolved in the latest (unreleased) version of the
source code. Thank you for bringing the issue to our attention!  You're
welcome and encouraged to test and make sure this issue is resolved after
the next source release of BRL-CAD.


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