Scaled centred sprites are skewed with pixel snap

[jusw85]

Godot version

3.4.4

System information

Arch Linux

Issue description

Related #42985

quality/2d/use_pixel_snap=true
2d/snapping/use_gpu_pixel_snap=true

Import a 1x1 sprite
centred=true
scale=(1, 1)

As expected.

centred=true
scale=(32,32)

Is this intended behaviour? The sprite origin is on the bottom right of the sprite instead of the centre of the scaled sprite. I expected the 32x32 sprite to be centred, with sprite origin at it's centre i.e. the sprite should be centred after being scaled.

This issue does not happen with textures with even dimensions.

Steps to reproduce

N.A.

Minimal reproduction project

TestPixelSnap2.zip

[lawnjelly]

Have limited time today, but this seems to have been the behaviour back to at least 3.2, possibly since GPU snap was first added.

I was kind of guessing that possibly the snap was being done before the scale was applied, but that doesn't seem to be the case in the shader (I may be missing something though). Anyone else that wants to look into this is welcome BTW.

EDIT: Ah there is also a snap in the CPU code it looks like from #42985 . Maybe this issue should be closed as a duplicate?

[jusw85]

Maybe this issue should be closed as a duplicate?

Yes, I see this issue as more of the root cause, while #42985 is a bug caused by this. Perhaps #42985 could be closed while this issue is used as the tracking issue.

[kleonc]

I think this shouldn't be there at all:

godot/scene/2d/sprite.cpp

Lines 102 to 104 in 3ba9803

	if (Engine::get_singleton()->get_use_gpu_pixel_snap()) {
	dest_offset = dest_offset.floor();
	}

GPU pixel snapping should be applied after all transformations are applied (so in the shader), there's no point to apply it locally (r_dst_rect in Sprite::_get_rects is local). Transforms are applied later when drawing (by the VisualServer based on the CanvasItem passed to Texture::draw_rect_region):

godot/scene/2d/sprite.cpp

Lines 118 to 133 in 3ba9803

	case NOTIFICATION_DRAW: {
	if (texture.is_null()) {
	return;
	}
	RID ci = get_canvas_item();
	/*
	texture->draw(ci,Point2());
	break;
	*/
	Rect2 src_rect, dst_rect;
	bool filter_clip;
	_get_rects(src_rect, dst_rect, filter_clip);
	texture->draw_rect_region(ci, dst_rect, src_rect, Color(1, 1, 1), false, normal_map, filter_clip);