Godot: Drawing a sprite with rotation

[MutantOctopus]

While I was browsing Reddit, I came across a post describing a "fake 3D" method in the game NIUM (thread here).

This seems like a really cool effect, and I was excited to experiment with it, but as I went into the Godot documentation I realized that there's absolutely no way to draw a sprite on the screen with a given rotation, barring manually manipulating the pixels yourself. While technically, you could achieve the same effect by stacking Sprite nodes as a child to the root node (which some people have suggested), this seems like it should be a remarkably inefficient process, as each node is receiving its own callbacks from the engine.

I'd like to request a simple, additional, optional parameter to the draw_texture function family which specifies an angle to rotate the sprite by when drawing it, much like Game Maker has in its draw_sprite_ext function.

For the record, when I was looking for a solution to this, I checked for, in order:

• A way to rotate the sprite when drawing it
• A way to make translations independent of rotation when drawing
• A way to rotate the ImageTexture/Texture before drawing it

None of these came out fruitfully, unless I completely missed something.

[vnen]

You can rotate (and translate and scale) if you call draw_set_transform or draw_set_transform_matrix before calling draw_texture().

[vnen]

BTW, using Sprite nodes is probably easier (since you can just set or animate the rotation) and I don't think it's inefficient. You can really add a lot of nodes before it starts taking a meaningful hit on performance. Sounds like premature optimization. Calling a lot of draw_ functions from GDScript is not the epitome of performance anyway.

[MutantOctopus]

Ah. I never noticed that function, I guess. Thanks, though, but incidentally - is there any way to tell when the object rotates without having to check its properties every process? I'm namely talking in-editor - I overrode just about every single rotation-related method on Node2D and superclasses with a print call and a superclass call, but nothing ever printed when I tried rotating the object in the editor.

[vnen]

No, I believe it's not possible to observe a property for changes. But a node doesn't rotate on its own, so you should be able to emit a custom signal when you change the rotation from code.

[MutantOctopus]

Ah, I was worried about that. I guess there's nothing to be done about the editor rotation, but actually now that I have the draw_set_transform detail I think this could go well. Thanks!

[vnen]

@MutantOctopus just found out it's actually possible to detect changes in the transform of a node (including rotation):

func _notification(what):
    if what == NOTIFICATION_TRANSFORM_CHANGED:
        # Do stuff when transform changed

Based on my test, this works even if you enable the Sync Scene Changes option and move or rotate the node in the editor.