Exact multi-precision arithmetic

[hm]

I am currently working on some collision detection code, and numerical precision seems to be one of the major challenges. Given that pretty much all intersection and interpenetration tests can be reduced to sign of determinant comparisons, I was wondering if anyone in this forum has already implemented a suitable set of primitives, i.e. a set of functions that calculate the exact sign (no over/underflow etc.) of 2x2, 3x3 and 4x4 determinants of 15.16 fixed point input coordinates.

- HM

[Structure]

[Dan East]

[Tala]

[hm]

[hm]

[Dan East]

I used the determinant method at first to see if a point was inside a poly. I don't remember any precision related problems at all with that technique - it seemed to work perfectly for line-poly collision detection.

I ended up using (precalculated) edge planes perpendicular to the poly normal. That works much better for volumetric collision.

Dan East