Merge pull request #78624 from puchik/canvas-background-specular-ghosting

Clear specular buffer if sky mode is canvas and screen space effects are used

servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp

@@ -2028,6 +2028,16 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 		}
 	}
 
+	if (using_separate_specular && is_environment(p_render_data->environment) && (environment_get_background(p_render_data->environment) == RS::ENV_BG_CANVAS)) {
+		// Canvas background mode does not clear the color buffer, but copies over it. If screen-space specular effects are enabled and the background is blank,
+		// this results in ghosting due to the separate specular buffer copy. Need to explicitly clear the specular buffer once we're done with it to fix it.
+		RENDER_TIMESTAMP("Clear Separate Specular (Canvas Background Mode)");
+		Vector<Color> blank_clear_color;
+		blank_clear_color.push_back(Color(0.0, 0.0, 0.0));
+		RD::get_singleton()->draw_list_begin(rb_data->get_specular_only_fb(), RD::INITIAL_ACTION_CLEAR, RD::FINAL_ACTION_READ, RD::INITIAL_ACTION_DROP, RD::FINAL_ACTION_DISCARD, blank_clear_color);
+		RD::get_singleton()->draw_list_end();
+	}
+
 	if (scene_state.used_screen_texture) {
 		RENDER_TIMESTAMP("Copy Screen Texture");