Add Transform.inverse()

[vtereshkov]

No description provided.

[skejeton]

I think it's something simple like this

result := {p: {-t.p.x, -t.p.y}, s: {1/t.s.x, 1/t.s.y}, r: -t.r, o: t.o}

[vtereshkov]

@skejeton Not that simple. You seem to ignore the order in which the translation, rotation and scaling are applied.

Even without rotations, the correct inverse is

result := {p: {-t.p.x / t.s.x, -t.p.y / t.s.y}, s: {1.0 / t.s.x, 1.0 / t.s.y}}

(notice that the p is also scaled).

[skejeton]

I need to experiment, I thought scaling was relative to the origin, but I'm also now not sure if the origin is relative to position.

[vtereshkov]

@skejeton The th.um documentation defines the following order:

scale
rotation
position

So the inverse should be

-position
-rotation
1 / scale

The origin parameter seems to be only used for rotations.