topic Re: Barycentric coordinates u v order in Intel® Embree Ray Tracing Kernels

Barycentric coordinates u v order

JeanBon1 — Sun, 12 Mar 2023 08:52:15 GMT

Hi, When intersecting with Embree, we get the u and v coordinates of the hit on the geometric shape (a triangle as far as i am concerned). Many sources will tell that the world coordinate is P1 = V0 * u + V1 * v + V2 * (1-u-v) and others P2 = V0 * (1-u-v) + V1 * u + V2 * v; In my scene, it is P2 that is correct and not P1. How to make sure which one I should use in Embree ? Is P1 always incorrect ? Thanks for the clarification,

Re: Barycentric coordinates u v order

SvenW_Intel — Mon, 13 Mar 2023 06:26:28 GMT

Embree always uses the second formula (V0 * (1-u-v) + V1 * u + V2 * v) for triangles. Please also see documentation section RTC_GEOMETRY_TYPE_TRIANGLE.

Re: Barycentric coordinates u v order

JeanBon1 — Mon, 13 Mar 2023 09:02:49 GMT

Thanks!

For some reasons I skipped the explanation in the doc.

My ray tracer works beautifully now. +1