func (p Sphere) Intersect(ray, origin glm.Vec3) (b bool, raylen float64, normal glm.Vec3) {
normal = glm.Vec3{}
line := *p.Pos.Subtract(&origin)
// Solve using cosine law for scalar coefficient of ray.
raylens := quadraticRoots(ray.Dot(&ray), 2*line.Dot(&ray), line.Dot(&line)-p.Rad*p.Rad)
switch len(raylens) {
case 0:
return false, 0, normal
case 1:
return ray_epsilon_check(-raylens[0], ray, line)
case 2:
if raylens[0] > raylens[1] { // NOTE: negative inversion
tmp := raylens[0]
raylens[0] = raylens[1]
raylens[1] = tmp
}
if b, raylen, normal = ray_epsilon_check(-raylens[1], ray, line); b {
return b, raylen, normal
} else {
return ray_epsilon_check(-raylens[0], ray, line)
}
}
return false, 0, normal
}
