[ quesa-Bugs-902592 ] TriMesh Colours go to the wrong faces

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Bugs item #902592, was opened at 2004-02-23 03:00
Message generated for change (Comment added) made by jwwalker
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Category: None
Group: None
>Status: Pending
>Resolution: Fixed
Priority: 5
Submitted By: Tom Sanham (tomsanham)
>Assigned to: James W. Walker (jwwalker)
Summary: TriMesh Colours go to the wrong faces

Initial Comment:
Quesa 1.6d18
OS used: Windows XP (not tested on Mac)

This bug affects cube shaped TriMeshes with 8 vertices 
which specify a colour attribute per face.

I believe that the described behaviour occurs because 
the model has >1 faces referencing the same vertex.


Behaviour:
The following strange behaviour was observed:

Setting Attribute 0 controls faces 0,4,5
Setting Attribute 1 controls face 1
Setting Attribute 2 controls faces 2,6,7,8,9,10
Setting Attribute 3 controls faces 3,11
Setting Attributes 4..11 has no visual effect

The same model renders correctly under QD3D - 
attribute n controls face n for 0<=n<12.


Workaround:
An effective workaround is to build the cube with 
duplicate vertices such that no vertex is shared by two 
faces.

Example trimesh included as a 3DMF.
Best viewed with kQ3InterpolationStyleNone

.triMeshAttributeSet = 0
.numTriangles = 12
.*triangles = 
    (4,6,2) ,
    (4,2,0) ,
    (1,3,7) ,
    (1,7,5) ,
    (5,7,6) ,
    (5,6,4) ,
    (0,2,3) ,
    (0,3,1) ,
    (2,6,3) ,
    (3,6,7) ,
    (4,0,1) ,
    (4,1,5) 
.numTriangleAttributeTypes = 1
.triangleAttributeTypes =
    .attributeType = kQ3AttributeTypeDiffuseColor
    .data =
    (1,0,0),
    (1,1,1),
    (1,1,1),
    remaining 9 faces (1,1,1)
.numEdges = 0
.edges = 0
.numEdgeAttributeTypes = 0
.*edgeAttributeTypes = 0
.numPoints = 8
.*points = 
    (0,0,0),
    (1,0,0),
    (0,1,0),
    (1,1,0),
    (0,0,1),
    (1,0,1),
    (0,1,1),
    (1,1,1)
.numVertexAttributeTypes =  0
.*vertexAttributeTypes = 0
.bBox = (0,0,0) , (10,10,10) , kQ3False

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>Comment By: James W. Walker (jwwalker)
Date: 2005-08-01 09:03

Message:
Logged In: YES 
user_id=433183

I believe this is now fixed in CVS for the interactive renderer.

----------------------------------------------------------------------

Comment By: James W. Walker (jwwalker)
Date: 2005-06-26 00:32

Message:
Logged In: YES 
user_id=433183

Quesa does not handle per-face colors correctly, it only uses them to infer 
vertex colors.  Therefore you get smooth color gradations when you 
expected sharp boundaries.

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