A analogy to barycentric coordinates: if alpha, beta, or gamma are less than 0 (negative), then the point of interest lies outside the triangle. Here, if t is negative, then we are looking "behind" the ray's origin.
A analogy to barycentric coordinates: if alpha, beta, or gamma are less than 0 (negative), then the point of interest lies outside the triangle. Here, if t is negative, then we are looking "behind" the ray's origin.