func (r *Ray) checkDir(v0, v1, v2, norm vec.V3d) bool {
//answer
if v1.Sub(v0).Cross(v2.Sub(v0)).Dot(norm) < 0 {
return false
}
return true
}
func (r *Ray) Intersect(t *Tri) (hit bool, depth float64, intersect vec.V3d) {
var v1, v2, norm vec.V3d
var dot, dist float64
hit = false
depth = math.Inf(1)
//vectors from triangle base to edges
v1 = t.V1.Sub(t.V0)
v2 = t.V2.Sub(t.V1)
//triangle normal
norm = v1.Cross(v2)
//if dot is zero, line is parallel
dot = norm.X*r.V.X + norm.Y*r.V.Y + norm.Z*r.V.Z
if dot < 0 {
//find intersect distance on ray
dist = -(norm.X*(r.P.X-t.V0.X) + norm.Y*(r.P.Y-t.V0.Y) + norm.Z*(r.P.Z-t.V0.Z)) / dot
dist = -(norm.Dot(r.P.Sub(t.V0))) / dot
//if negative, line started after the triangle
if dist < 0 {
return
}
intersect = r.P.Add(r.V.Mul(dist))
if r.checkDir(t.V0, t.V1, intersect, norm) && r.checkDir(t.V1, t.V2, intersect, norm) && r.checkDir(t.V2, t.V0, intersect, norm) {
hit = true
depth = dist
}
}
return
}