func RenderArrow(pos, dir *Vec3) {
const tolerance = 0.0001
arrow := Get("arrow")
l := dir.Length()
d0 := dir.Unit()
zaxis := V3(0, 0, 1)
arrow.Mat = mat4.Scaling(V3(.1*l, .1*l, .5*l))
angle := zaxis.Angle(d0)
if angle > tolerance && math.Pi-angle > tolerance {
arrow.Mat = arrow.Mat.Mul(mat4.RotationAxis(zaxis.Add(d0).Unit(), math.Pi))
} else if math.Pi-angle <= tolerance {
arrow.Mat = arrow.Mat.Mul(mat4.Scaling(V3(1, 1, -1)))
}
arrow.Mat = arrow.Mat.Mul(mat4.Translation(pos.Add(dir.Muls(.5))))
arrow.Render()
}
func (t *Nurbs) DebugRender() {
t.Render()
m := model.Get("cube")
t.ForEachNode(func(n *Node) {
m.Mat = mat4.Scaling(V3(1, 1, 1).Muls(1.1))
m.Mat = m.Mat.Mul(mat4.Translation(n.P))
m.Render()
model.RenderArrow(n.P, n.Tu.Muls(1.0))
model.RenderArrow(n.P, n.Tv.Muls(1.0))
})
}