Normalizing a bvh::Triangle's normal... about bvh HOT 3 CLOSED

The normal stored in the triangle is here to speed up the intersection routine. It's just some precomputed data to solve the system of equations coming from the Möller-Trumbore method. It just so happens to be the cross product of two edges, which is the (not unit length) normal of the triangle. It is possible to recompute this all the time during intersections (just like it is possible to store the points on the triangle, instead of storing one vertex and two edges), but that is obviously going to incur a performance penalty. The layout chosen here is exactly the one used in Embree, for performance reasons. If you want to, you can create your own triangle primitive that only stores three points, and just recompute e1, e2, and n everytime, but I am not sure that this is less expensive than computing the real normal by normalizing n after BVH traversal.

from bvh.

Of course I would not want to recalculate everything every time.
I understand now that n is used internally by bvh::Triangle for performance reasons, and not supposed to be used externally for other purposes...

Thanks again for your quick reply...

from bvh.

No problem. Closing the issue then.

from bvh.