This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
vtkPolygon::IntersectPolygonWithPolygon() incorrectly return false that two triangles are intersecting when two triangles are intersecting each other exactly at their edges...
The fix for this is in vtkTriangle::PointInTriangle(). At the moment vtkTriangle::PointInTriangle returns true if a point is inside but not on the edge of the triangle. So line 958 of vtkTriangle.cxx should change to:
if ( (vtkMath::Dot(n1,n2) >= 0.0) && (vtkMath::Dot(n2,n3) >= 0.0) )
to include the edges.