Fix GPUParticles2D ignoring AtlasTexture region

scene/2d/gpu_particles_2d.cpp

@@ -30,6 +30,7 @@
 
 #include "gpu_particles_2d.h"
 
+#include "core/core_string_names.h"
 #include "scene/resources/particle_process_material.h"
 
 #ifdef TOOLS_ENABLED
@@ -331,7 +332,15 @@ Rect2 GPUParticles2D::capture_rect() const {
 }
 
 void GPUParticles2D::set_texture(const Ref<Texture2D> &p_texture) {
+	if (texture.is_valid()) {
+		texture->disconnect(CoreStringNames::get_singleton()->changed, callable_mp(this, &GPUParticles2D::_texture_changed));
+	}
+
 	texture = p_texture;
+
+	if (texture.is_valid()) {
+		texture->connect(CoreStringNames::get_singleton()->changed, callable_mp(this, &GPUParticles2D::_texture_changed));
+	}
 	_update_collision_size();
 	update();
 }
@@ -363,6 +372,14 @@ void GPUParticles2D::_attach_sub_emitter() {
 	}
 }
 
+void GPUParticles2D::_texture_changed() {
+	// Changes to the texture need to trigger an update to make
+	// the editor redraw the sprite with the updated texture.
+	if (texture.is_valid()) {
+		update();
+	}
+}
+
 void GPUParticles2D::set_sub_emitter(const NodePath &p_path) {
 	if (is_inside_tree()) {
 		RS::get_singleton()->particles_set_subemitter(particles, RID());
@@ -480,12 +497,21 @@ void GPUParticles2D::_notification(int p_what) {
 					Vector2(-size.x / 2.0, size.y / 2.0)
 				};
 
-				Vector<Vector2> uvs = {
-					Vector2(0, 0),
-					Vector2(1, 0),
-					Vector2(1, 1),
-					Vector2(0, 1)
-				};
+				Vector<Vector2> uvs;
+				AtlasTexture *atlas_texure = Object::cast_to<AtlasTexture>(*texture);
+				if (atlas_texure && atlas_texure->get_atlas().is_valid()) {
+					Rect2 region_rect = atlas_texure->get_region();
+					Size2 atlas_size = atlas_texure->get_atlas()->get_size();
+					uvs.push_back(Vector2(region_rect.position.x / atlas_size.x, region_rect.position.y / atlas_size.y));
+					uvs.push_back(Vector2((region_rect.position.x + region_rect.size.x) / atlas_size.x, region_rect.position.y / atlas_size.y));
+					uvs.push_back(Vector2((region_rect.position.x + region_rect.size.x) / atlas_size.x, (region_rect.position.y + region_rect.size.y) / atlas_size.y));
+					uvs.push_back(Vector2(region_rect.position.x / atlas_size.x, (region_rect.position.y + region_rect.size.y) / atlas_size.y));
+				} else {
+					uvs.push_back(Vector2(0, 0));
+					uvs.push_back(Vector2(1, 0));
+					uvs.push_back(Vector2(1, 1));
+					uvs.push_back(Vector2(0, 1));
+				}
 
 				Vector<int> indices = { 0, 1, 2, 0, 2, 3 };
 

scene/2d/gpu_particles_2d.h

@@ -82,6 +82,8 @@ private:
 
 	void _attach_sub_emitter();
 
+	void _texture_changed();
+
 protected:
 	static void _bind_methods();
 	void _validate_property(PropertyInfo &p_property) const;