BTW, I tested the Moller / Trumbore Fast, Minimum Storage Ray/Triangle Intersection code in my other plugin and it suffers from similar rounding-error issues as the current point-in-tri code based on Dan Sunday's Intersections of Rays, Segments, Planes and Triangles in 3D code (which itself is based on the Moller / Trumbore code).  I haven't studied your implementation of the Moller / Trumbore code, so it's possible that you got it working fine, but I'm not sure it buys you anything over the current implementation (assuming the epsilon/tolerance values are set correctly in each).

The biggest distinction between the two is that the original Moller / Trumbore code doesn't require pre-computing/storing the tripoly 'plane' equations.

Without spending more time adjusting the Moller / Trumbore code, so far, my best results have come from the current Sunday-based implementation.

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