Refactor pixel snapping.

-Rename pixel_snap to snap_2d_to_vertices
-Added snap_2d_to_transforms which is more useful

Fixes #41814
Solves proposal https://github.com/godotengine/godot-proposals/issues/1666
Supersedes #35606, supersedes #41535, supersedes #41534

11 files changed, 66 insertions, 22 deletions

diff --git a/servers/rendering/rasterizer.h b/servers/rendering/rasterizer.h
index 88b92bd35d..b2b2b4977b 100644
--- a/servers/rendering/rasterizer.h
+++ b/servers/rendering/rasterizer.h
@@ -1322,7 +1322,7 @@ public:
 		}
 	};
 
-	virtual void canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat) = 0;
+	virtual void canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_vertices_to_pixel) = 0;
 	virtual void canvas_debug_viewport_shadows(Light *p_lights_with_shadow) = 0;
 
 	struct LightOccluderInstance {
diff --git a/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.cpp b/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.cpp
index b268db5989..da30291353 100644
--- a/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.cpp
+++ b/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.cpp
@@ -1194,7 +1194,7 @@ void RasterizerCanvasRD::_render_items(RID p_to_render_target, int p_item_count,
 	RD::get_singleton()->draw_list_end();
 }
 
-void RasterizerCanvasRD::canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat) {
+void RasterizerCanvasRD::canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_vertices_to_pixel) {
 	int item_count = 0;
 
 	//setup canvas state uniforms if needed
@@ -1229,6 +1229,8 @@ void RasterizerCanvasRD::canvas_render_items(RID p_to_render_target, Item *p_ite
 		state_buffer.screen_pixel_size[1] = 1.0 / render_target_size.y;
 
 		state_buffer.time = state.time;
+		state_buffer.use_pixel_snap = p_snap_2d_vertices_to_pixel;
+
 		RD::get_singleton()->buffer_update(state.canvas_state_buffer, 0, sizeof(State::Buffer), &state_buffer, true);
 	}
 
diff --git a/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.h b/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.h
index 4a79134c24..3412435367 100644
--- a/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.h
+++ b/servers/rendering/rasterizer_rd/rasterizer_canvas_rd.h
@@ -79,7 +79,6 @@ class RasterizerCanvasRD : public RasterizerCanvas {
 
 		FLAGS_NINEPACH_DRAW_CENTER = (1 << 12),
 		FLAGS_USING_PARTICLES = (1 << 13),
-		FLAGS_USE_PIXEL_SNAP = (1 << 14),
 
 		FLAGS_USE_SKELETON = (1 << 15),
 		FLAGS_NINEPATCH_H_MODE_SHIFT = 16,
@@ -334,7 +333,7 @@ class RasterizerCanvasRD : public RasterizerCanvas {
 			float canvas_modulate[4];
 			float screen_pixel_size[2];
 			float time;
-			float pad;
+			uint32_t use_pixel_snap;
 
 			//uint32_t light_count;
 			//uint32_t pad[3];
@@ -422,7 +421,7 @@ public:
 	void occluder_polygon_set_shape_as_lines(RID p_occluder, const Vector<Vector2> &p_lines);
 	void occluder_polygon_set_cull_mode(RID p_occluder, RS::CanvasOccluderPolygonCullMode p_mode);
 
-	void canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat);
+	void canvas_render_items(RID p_to_render_target, Item *p_item_list, const Color &p_modulate, Light *p_light_list, const Transform2D &p_canvas_transform, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_vertices_to_pixel);
 
 	void canvas_debug_viewport_shadows(Light *p_lights_with_shadow) {}
 
diff --git a/servers/rendering/rasterizer_rd/shaders/canvas.glsl b/servers/rendering/rasterizer_rd/shaders/canvas.glsl
index 04a37e501f..b382c0d85f 100644
--- a/servers/rendering/rasterizer_rd/shaders/canvas.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/canvas.glsl
@@ -144,7 +144,7 @@ VERTEX_SHADER_CODE
 
 	color_interp = color;
 
-	if (bool(draw_data.flags & FLAGS_USE_PIXEL_SNAP)) {
+	if (canvas_data.use_pixel_snap) {
 		vertex = floor(vertex + 0.5);
 		// precision issue on some hardware creates artifacts within texture
 		// offset uv by a small amount to avoid
diff --git a/servers/rendering/rasterizer_rd/shaders/canvas_uniforms_inc.glsl b/servers/rendering/rasterizer_rd/shaders/canvas_uniforms_inc.glsl
index e4dc326af6..1a226a87d3 100644
--- a/servers/rendering/rasterizer_rd/shaders/canvas_uniforms_inc.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/canvas_uniforms_inc.glsl
@@ -15,7 +15,6 @@
 #define FLAGS_USING_LIGHT_MASK (1 << 11)
 #define FLAGS_NINEPACH_DRAW_CENTER (1 << 12)
 #define FLAGS_USING_PARTICLES (1 << 13)
-#define FLAGS_USE_PIXEL_SNAP (1 << 14)
 
 #define FLAGS_NINEPATCH_H_MODE_SHIFT 16
 #define FLAGS_NINEPATCH_V_MODE_SHIFT 18
@@ -67,7 +66,8 @@ layout(set = 0, binding = 1, std140) uniform CanvasData {
 	vec4 canvas_modulation;
 	vec2 screen_pixel_size;
 	float time;
-	float time_pad;
+	bool use_pixel_snap;
+
 	//uint light_count;
 }
 canvas_data;
diff --git a/servers/rendering/rendering_server_canvas.cpp b/servers/rendering/rendering_server_canvas.cpp
index f06667a460..fd7c022d62 100644
--- a/servers/rendering/rendering_server_canvas.cpp
+++ b/servers/rendering/rendering_server_canvas.cpp
@@ -37,7 +37,7 @@
 
 static const int z_range = RS::CANVAS_ITEM_Z_MAX - RS::CANVAS_ITEM_Z_MIN + 1;
 
-void RenderingServerCanvas::_render_canvas_item_tree(RID p_to_render_target, Canvas::ChildItem *p_child_items, int p_child_item_count, Item *p_canvas_item, const Transform2D &p_transform, const Rect2 &p_clip_rect, const Color &p_modulate, RasterizerCanvas::Light *p_lights, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat) {
+void RenderingServerCanvas::_render_canvas_item_tree(RID p_to_render_target, Canvas::ChildItem *p_child_items, int p_child_item_count, Item *p_canvas_item, const Transform2D &p_transform, const Rect2 &p_clip_rect, const Color &p_modulate, RasterizerCanvas::Light *p_lights, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_vertices_to_pixel) {
 	RENDER_TIMESTAMP("Cull CanvasItem Tree");
 
 	memset(z_list, 0, z_range * sizeof(RasterizerCanvas::Item *));
@@ -68,7 +68,7 @@ void RenderingServerCanvas::_render_canvas_item_tree(RID p_to_render_target, Can
 
 	RENDER_TIMESTAMP("Render Canvas Items");
 
-	RSG::canvas_render->canvas_render_items(p_to_render_target, list, p_modulate, p_lights, p_transform, p_default_filter, p_default_repeat);
+	RSG::canvas_render->canvas_render_items(p_to_render_target, list, p_modulate, p_lights, p_transform, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 }
 
 void _collect_ysort_children(RenderingServerCanvas::Item *p_canvas_item, Transform2D p_transform, RenderingServerCanvas::Item *p_material_owner, RenderingServerCanvas::Item **r_items, int &r_index) {
@@ -113,7 +113,12 @@ void RenderingServerCanvas::_cull_canvas_item(Item *p_canvas_item, const Transfo
 	}
 
 	Rect2 rect = ci->get_rect();
-	Transform2D xform = p_transform * ci->xform;
+	Transform2D xform = ci->xform;
+	if (snapping_2d_transforms_to_pixel) {
+		xform.elements[2].floor();
+	}
+	xform = p_transform * xform;
+
 	Rect2 global_rect = xform.xform(rect);
 	global_rect.position += p_clip_rect.position;
 
@@ -314,9 +319,11 @@ void RenderingServerCanvas::_light_mask_canvas_items(int p_z, RasterizerCanvas::
 	}
 }
 
-void RenderingServerCanvas::render_canvas(RID p_render_target, Canvas *p_canvas, const Transform2D &p_transform, RasterizerCanvas::Light *p_lights, RasterizerCanvas::Light *p_masked_lights, const Rect2 &p_clip_rect, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat) {
+void RenderingServerCanvas::render_canvas(RID p_render_target, Canvas *p_canvas, const Transform2D &p_transform, RasterizerCanvas::Light *p_lights, RasterizerCanvas::Light *p_masked_lights, const Rect2 &p_clip_rect, RenderingServer::CanvasItemTextureFilter p_default_filter, RenderingServer::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_transforms_to_pixel, bool p_snap_2d_vertices_to_pixel) {
 	RENDER_TIMESTAMP(">Render Canvas");
 
+	snapping_2d_transforms_to_pixel = p_snap_2d_transforms_to_pixel;
+
 	if (p_canvas->children_order_dirty) {
 		p_canvas->child_items.sort();
 		p_canvas->children_order_dirty = false;
@@ -334,26 +341,26 @@ void RenderingServerCanvas::render_canvas(RID p_render_target, Canvas *p_canvas,
 	}
 
 	if (!has_mirror) {
-		_render_canvas_item_tree(p_render_target, ci, l, nullptr, p_transform, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat);
+		_render_canvas_item_tree(p_render_target, ci, l, nullptr, p_transform, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 
 	} else {
 		//used for parallaxlayer mirroring
 		for (int i = 0; i < l; i++) {
 			const Canvas::ChildItem &ci2 = p_canvas->child_items[i];
-			_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, p_transform, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat);
+			_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, p_transform, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 
 			//mirroring (useful for scrolling backgrounds)
 			if (ci2.mirror.x != 0) {
 				Transform2D xform2 = p_transform * Transform2D(0, Vector2(ci2.mirror.x, 0));
-				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat);
+				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 			}
 			if (ci2.mirror.y != 0) {
 				Transform2D xform2 = p_transform * Transform2D(0, Vector2(0, ci2.mirror.y));
-				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat);
+				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 			}
 			if (ci2.mirror.y != 0 && ci2.mirror.x != 0) {
 				Transform2D xform2 = p_transform * Transform2D(0, ci2.mirror);
-				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat);
+				_render_canvas_item_tree(p_render_target, nullptr, 0, ci2.item, xform2, p_clip_rect, p_canvas->modulate, p_lights, p_default_filter, p_default_repeat, p_snap_2d_vertices_to_pixel);
 			}
 		}
 	}
diff --git a/servers/rendering/rendering_server_canvas.h b/servers/rendering/rendering_server_canvas.h
index 8eed6e72d9..a9a81888aa 100644
--- a/servers/rendering/rendering_server_canvas.h
+++ b/servers/rendering/rendering_server_canvas.h
@@ -152,9 +152,10 @@ public:
 	RID_PtrOwner<RasterizerCanvas::Light> canvas_light_owner;
 
 	bool disable_scale;
+	bool snapping_2d_transforms_to_pixel = false;
 
 private:
-	void _render_canvas_item_tree(RID p_to_render_target, Canvas::ChildItem *p_child_items, int p_child_item_count, Item *p_canvas_item, const Transform2D &p_transform, const Rect2 &p_clip_rect, const Color &p_modulate, RasterizerCanvas::Light *p_lights, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat);
+	void _render_canvas_item_tree(RID p_to_render_target, Canvas::ChildItem *p_child_items, int p_child_item_count, Item *p_canvas_item, const Transform2D &p_transform, const Rect2 &p_clip_rect, const Color &p_modulate, RasterizerCanvas::Light *p_lights, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_vertices_to_pixel);
 	void _cull_canvas_item(Item *p_canvas_item, const Transform2D &p_transform, const Rect2 &p_clip_rect, const Color &p_modulate, int p_z, RasterizerCanvas::Item **z_list, RasterizerCanvas::Item **z_last_list, Item *p_canvas_clip, Item *p_material_owner);
 	void _light_mask_canvas_items(int p_z, RasterizerCanvas::Item *p_canvas_item, RasterizerCanvas::Light *p_masked_lights);
 
@@ -162,7 +163,7 @@ private:
 	RasterizerCanvas::Item **z_last_list;
 
 public:
-	void render_canvas(RID p_render_target, Canvas *p_canvas, const Transform2D &p_transform, RasterizerCanvas::Light *p_lights, RasterizerCanvas::Light *p_masked_lights, const Rect2 &p_clip_rect, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat);
+	void render_canvas(RID p_render_target, Canvas *p_canvas, const Transform2D &p_transform, RasterizerCanvas::Light *p_lights, RasterizerCanvas::Light *p_masked_lights, const Rect2 &p_clip_rect, RS::CanvasItemTextureFilter p_default_filter, RS::CanvasItemTextureRepeat p_default_repeat, bool p_snap_2d_transforms_to_pixel, bool p_snap_2d_vertices_to_pixel);
 
 	RID canvas_create();
 	void canvas_set_item_mirroring(RID p_canvas, RID p_item, const Point2 &p_mirroring);
diff --git a/servers/rendering/rendering_server_raster.h b/servers/rendering/rendering_server_raster.h
index 1c222a48c4..a89d4db1f8 100644
--- a/servers/rendering/rendering_server_raster.h
+++ b/servers/rendering/rendering_server_raster.h
@@ -528,6 +528,8 @@ public:
 	BIND2(viewport_remove_canvas, RID, RID)
 	BIND3(viewport_set_canvas_transform, RID, RID, const Transform2D &)
 	BIND2(viewport_set_transparent_background, RID, bool)
+	BIND2(viewport_set_snap_2d_transforms_to_pixel, RID, bool)
+	BIND2(viewport_set_snap_2d_vertices_to_pixel, RID, bool)
 
 	BIND2(viewport_set_default_canvas_item_texture_filter, RID, CanvasItemTextureFilter)
 	BIND2(viewport_set_default_canvas_item_texture_repeat, RID, CanvasItemTextureRepeat)
diff --git a/servers/rendering/rendering_server_viewport.cpp b/servers/rendering/rendering_server_viewport.cpp
index a8dbe1e254..b5d8f0da40 100644
--- a/servers/rendering/rendering_server_viewport.cpp
+++ b/servers/rendering/rendering_server_viewport.cpp
@@ -40,11 +40,21 @@ static Transform2D _canvas_get_transform(RenderingServerViewport::Viewport *p_vi
 
 	float scale = 1.0;
 	if (p_viewport->canvas_map.has(p_canvas->parent)) {
-		xf = xf * p_viewport->canvas_map[p_canvas->parent].transform;
+		Transform2D c_xform = p_viewport->canvas_map[p_canvas->parent].transform;
+		if (p_viewport->snap_2d_transforms_to_pixel) {
+			c_xform.elements[2] = c_xform.elements[2].floor();
+		}
+		xf = xf * c_xform;
 		scale = p_canvas->parent_scale;
 	}
 
-	xf = xf * p_canvas_data->transform;
+	Transform2D c_xform = p_canvas_data->transform;
+
+	if (p_viewport->snap_2d_transforms_to_pixel) {
+		c_xform.elements[2] = c_xform.elements[2].floor();
+	}
+
+	xf = xf * c_xform;
 
 	if (scale != 1.0 && !RSG::canvas->disable_scale) {
 		Vector2 pivot = p_vp_size * 0.5;
@@ -255,7 +265,7 @@ void RenderingServerViewport::_draw_viewport(Viewport *p_viewport, XRInterface::
 				ptr = ptr->filter_next_ptr;
 			}
 
-			RSG::canvas->render_canvas(p_viewport->render_target, canvas, xform, canvas_lights, lights_with_mask, clip_rect, p_viewport->texture_filter, p_viewport->texture_repeat);
+			RSG::canvas->render_canvas(p_viewport->render_target, canvas, xform, canvas_lights, lights_with_mask, clip_rect, p_viewport->texture_filter, p_viewport->texture_repeat, p_viewport->snap_2d_transforms_to_pixel, p_viewport->snap_2d_vertices_to_pixel);
 			i++;
 
 			if (scenario_draw_canvas_bg && E->key().get_layer() >= scenario_canvas_max_layer) {
@@ -774,6 +784,18 @@ float RenderingServerViewport::viewport_get_measured_render_time_gpu(RID p_viewp
 	return double((viewport->time_gpu_end - viewport->time_gpu_begin) / 1000) / 1000.0;
 }
 
+void RenderingServerViewport::viewport_set_snap_2d_transforms_to_pixel(RID p_viewport, bool p_enabled) {
+	Viewport *viewport = viewport_owner.getornull(p_viewport);
+	ERR_FAIL_COND(!viewport);
+	viewport->snap_2d_transforms_to_pixel = p_enabled;
+}
+
+void RenderingServerViewport::viewport_set_snap_2d_vertices_to_pixel(RID p_viewport, bool p_enabled) {
+	Viewport *viewport = viewport_owner.getornull(p_viewport);
+	ERR_FAIL_COND(!viewport);
+	viewport->snap_2d_vertices_to_pixel = p_enabled;
+}
+
 void RenderingServerViewport::viewport_set_default_canvas_item_texture_filter(RID p_viewport, RS::CanvasItemTextureFilter p_filter) {
 	ERR_FAIL_COND_MSG(p_filter == RS::CANVAS_ITEM_TEXTURE_FILTER_DEFAULT, "Viewport does not accept DEFAULT as texture filter (it's the topmost choice already).)");
 	Viewport *viewport = viewport_owner.getornull(p_viewport);
diff --git a/servers/rendering/rendering_server_viewport.h b/servers/rendering/rendering_server_viewport.h
index 161ae94fb0..d00a06c5ee 100644
--- a/servers/rendering/rendering_server_viewport.h
+++ b/servers/rendering/rendering_server_viewport.h
@@ -70,6 +70,9 @@ public:
 		bool disable_environment;
 		bool measure_render_time;
 
+		bool snap_2d_transforms_to_pixel;
+		bool snap_2d_vertices_to_pixel;
+
 		uint64_t time_cpu_begin;
 		uint64_t time_cpu_end;
 
@@ -136,6 +139,9 @@ public:
 			screen_space_aa = RS::VIEWPORT_SCREEN_SPACE_AA_DISABLED;
 			use_debanding = false;
 
+			snap_2d_transforms_to_pixel = false;
+			snap_2d_vertices_to_pixel = false;
+
 			for (int i = 0; i < RS::VIEWPORT_RENDER_INFO_MAX; i++) {
 				render_info[i] = 0;
 			}
@@ -220,6 +226,9 @@ public:
 	float viewport_get_measured_render_time_cpu(RID p_viewport) const;
 	float viewport_get_measured_render_time_gpu(RID p_viewport) const;
 
+	void viewport_set_snap_2d_transforms_to_pixel(RID p_viewport, bool p_enabled);
+	void viewport_set_snap_2d_vertices_to_pixel(RID p_viewport, bool p_enabled);
+
 	void viewport_set_default_canvas_item_texture_filter(RID p_viewport, RS::CanvasItemTextureFilter p_filter);
 	void viewport_set_default_canvas_item_texture_repeat(RID p_viewport, RS::CanvasItemTextureRepeat p_repeat);
 
diff --git a/servers/rendering/rendering_server_wrap_mt.h b/servers/rendering/rendering_server_wrap_mt.h
index 89fd713265..42f1b5bcc8 100644
--- a/servers/rendering/rendering_server_wrap_mt.h
+++ b/servers/rendering/rendering_server_wrap_mt.h
@@ -431,6 +431,8 @@ public:
 	FUNC2(viewport_remove_canvas, RID, RID)
 	FUNC3(viewport_set_canvas_transform, RID, RID, const Transform2D &)
 	FUNC2(viewport_set_transparent_background, RID, bool)
+	FUNC2(viewport_set_snap_2d_transforms_to_pixel, RID, bool)
+	FUNC2(viewport_set_snap_2d_vertices_to_pixel, RID, bool)
 
 	FUNC2(viewport_set_default_canvas_item_texture_filter, RID, CanvasItemTextureFilter)
 	FUNC2(viewport_set_default_canvas_item_texture_repeat, RID, CanvasItemTextureRepeat)