Does the collada specification support texture seams in any way? I just glanced through the docs and didn’t see anything talking about it. It seems all the attributes are stored per vertex and there’s no option for per-face/vertex so one vertex can only have one UV coordinate. Does that mean the export implementation has to export a separate vertex for every edge or is there a different mechanism for handling texture seams?
There are two ways to do that.
first is to specify UV coordinates in the <source> <vertices>.
this is where data is attached per vertex, with at minimum the “POSITION” of course.
<vertices id="_1344-vertices">
<input semantic="POSITION" source="#my-positions" />
<input semantic="TEXCOORD" source="#my-uv" />
</vertices>
But I noticed that the in the does not have support for set attribute.
So probably you want to use the
element and use the same index for your UV than you have for your vertices
<triangles count="2" material="material-0">
<input offset="0" semantic="VERTEX" source="#my-vertices" />
<input offset="0" semantic="TEXCOORD" source="#my-uv0" set="0" />
...</p>
using the same offest for VERTEX and TEXCOORD, you’ll have to provide one UV set per vertex.