Good to hear! To clarify: The problem still occurs when executing in sequential mode? Or did you adapt the code somehow?
IndicatorTriangle2D
is what you want for a plain triangle shape in 2D. (The smooth versions project on [0,1] instead of {0,1} for use in the HLBM particle code)
However I suspect that you want to construct a triangle geometry in 3D? If so the recommended way is to load a STL file (which describes just such a triangle geometry) using the STL reader class. This is used in the aorta3d
example you are already familiar with.