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General Category => ASL Scripts => Topic started by: Claude on March 12, 2009, 02:56:21 pm

Title: Question about GetEdgeIndex() function.
Post by: Claude on March 12, 2009, 02:56:21 pm

GetEdgeIndex() returns the index of a particular edge in a face.  The value returned can be positive or negative.  If it is negative the edge is reversed when the face is viewed with the vertices in a clockwise orientation.

If you have 2 quads sharing 1 edge and the 2 quads are facing the same way,then the function should return different result for each quad for the shared edge.One should be positive the other negative.

I thought I could use this feature to define if 2 quads sharing an edge, were facing the same way,but I'm unable to obtain any negative result.
Is it because I misunderstand how it should work or the function doesn't
work properly?

Thanks
Claude

Title: Re: Question about GetEdgeIndex() function.
Post by: Steve on March 14, 2009, 06:46:53 pm

The documentation and the implementation don't agree.  GetEdgeIndex() currently returns a positive number for an edge, and a negative value if the face number or edge number is out of range.  It seems like it's better to return 0 for an error and positive/negative numbers as indicated.

But I want to hear from people before I decide if I should fix the function or the documentation.  I don't want to break too many existing scripts!

#097-028 - GetEdgeIndex() always returns a positive number.

Title: Re: Question about GetEdgeIndex() function.
Post by: Claude on March 15, 2009, 11:36:34 pm

If it could be used the way I described,to check the relative
orientation of faces,I think it should be implemented.It
would be a lot easier then calculating the normals and
testing their dot product.

I see your point about backward compatibility,but there's
2 mitigating factors:
-this function isn't normally used in export and primitive script,
 only in a limited number of command script;
-the correction seems to be easy enough:
abs(GetEdgeIndex())

Just a thought.
Hope it helps.
Claude

Title: Re: Question about GetEdgeIndex() function.
Post by: Kubajzz on March 16, 2009, 03:17:24 am

Quote from: Steve

But I want to hear from people before I decide if I should fix the function or the documentation.  I don't want to break too many existing scripts!

From my point of view it doesn't matter... If you change the function, I don't mind editing my older scripts the way Claude suggested. If you leave it as it is now, I don't mind either ;)