func (this *World) PortalTransform(pos1, pos2 mgl.Vec4) mgl.Mat4 {
portal := this.NearestPortal(pos1)
m := portal.View()
pos1 = m.Mul4x1(pos1)
pos2 = m.Mul4x1(pos2)
n := portal.Normal
a := n.Dot(pos1)
b := n.Dot(pos2)
var portalPassed bool
if a*b < 0 {
c := a / (a - b)
pos3 := pos1.Mul(c).Add(pos2.Mul(1 - c))
portalPassed = -1 < pos3[0] && pos3[0] < 1 && -1 < pos3[1] && pos3[1] < 1
} else {
portalPassed = false
}
if portalPassed {
return portal.Transform()
} else {
return mgl.Ident4()
}
}
func Homogen(v mgl.Vec4) mgl.Vec4 {
return v.Mul(1 / v[3])
}