Function ray_triangle_intersection 

fn ray_triangle_intersection(
    origin: Vec3,
    dir: Vec3,
    v0: Vec3,
    v1: Vec3,
    v2: Vec3,
) -> Option<f32>

Möller–Trumbore ray/triangle intersection. Double-sided (doesn’t consider winding order), since picking should hit a triangle regardless of which way it faces the camera.