Merge pull request #75181 from dalexeev/fix-light-only-mode

Fix "Light Only" mode of `CanvasItemMaterial`

drivers/gles3/rasterizer_canvas_gles3.cpp

@@ -175,7 +175,7 @@ void RasterizerCanvasGLES3::canvas_render_items(RID p_to_render_target, Item *p_
 				state.light_uniforms[index].color[i] = l->color[i];
 			}
 
-			state.light_uniforms[index].color[3] = l->energy; //use alpha for energy, so base color can go separate
+			state.light_uniforms[index].color[3] *= l->energy; //use alpha for energy, so base color can go separate
 
 			if (state.shadow_fb != 0) {
 				state.light_uniforms[index].shadow_pixel_size = (1.0 / state.shadow_texture_size) * (1.0 + l->shadow_smooth);
@@ -238,7 +238,7 @@ void RasterizerCanvasGLES3::canvas_render_items(RID p_to_render_target, Item *p_
 				state.light_uniforms[index].color[i] = l->color[i];
 			}
 
-			state.light_uniforms[index].color[3] = l->energy; //use alpha for energy, so base color can go separate
+			state.light_uniforms[index].color[3] *= l->energy; //use alpha for energy, so base color can go separate
 
 			if (state.shadow_fb != 0) {
 				state.light_uniforms[index].shadow_pixel_size = (1.0 / state.shadow_texture_size) * (1.0 + l->shadow_smooth);

drivers/gles3/shaders/canvas.glsl

@@ -648,7 +648,7 @@ void main() {
 	vec4 base_color = color;
 
 #ifdef MODE_LIGHT_ONLY
-	color = vec4(0.0);
+	float light_only_alpha = 0.0;
 #elif !defined(MODE_UNSHADED)
 	color *= canvas_modulation;
 #endif
@@ -691,6 +691,9 @@ void main() {
 		}
 
 		light_blend_compute(light_base, light_color, color.rgb);
+#ifdef MODE_LIGHT_ONLY
+		light_only_alpha += light_color.a;
+#endif
 	}
 
 	// Positional Lights
@@ -788,8 +791,15 @@ void main() {
 		}
 
 		light_blend_compute(light_base, light_color, color.rgb);
+#ifdef MODE_LIGHT_ONLY
+		light_only_alpha += light_color.a;
+#endif
 	}
 #endif
 
+#ifdef MODE_LIGHT_ONLY
+	color.a *= light_only_alpha;
+#endif
+
 	frag_color = color;
 }

servers/rendering/renderer_rd/renderer_canvas_render_rd.cpp

@@ -1202,7 +1202,7 @@ void RendererCanvasRenderRD::canvas_render_items(RID p_to_render_target, Item *p
 				state.light_uniforms[index].color[i] = l->color[i];
 			}
 
-			state.light_uniforms[index].color[3] = l->energy; //use alpha for energy, so base color can go separate
+			state.light_uniforms[index].color[3] *= l->energy; //use alpha for energy, so base color can go separate
 
 			if (state.shadow_fb.is_valid()) {
 				state.light_uniforms[index].shadow_pixel_size = (1.0 / state.shadow_texture_size) * (1.0 + l->shadow_smooth);
@@ -1264,7 +1264,7 @@ void RendererCanvasRenderRD::canvas_render_items(RID p_to_render_target, Item *p
 				state.light_uniforms[index].color[i] = l->color[i];
 			}
 
-			state.light_uniforms[index].color[3] = l->energy; //use alpha for energy, so base color can go separate
+			state.light_uniforms[index].color[3] *= l->energy; //use alpha for energy, so base color can go separate
 
 			if (state.shadow_fb.is_valid()) {
 				state.light_uniforms[index].shadow_pixel_size = (1.0 / state.shadow_texture_size) * (1.0 + l->shadow_smooth);

servers/rendering/renderer_rd/shaders/canvas.glsl

@@ -568,7 +568,7 @@ void main() {
 	}
 
 #ifdef MODE_LIGHT_ONLY
-	color = vec4(0.0);
+	float light_only_alpha = 0.0;
 #elif !defined(MODE_UNSHADED)
 	color *= canvas_data.canvas_modulation;
 #endif
@@ -611,6 +611,9 @@ void main() {
 		}
 
 		light_blend_compute(light_base, light_color, color.rgb);
+#ifdef MODE_LIGHT_ONLY
+		light_only_alpha += light_color.a;
+#endif
 	}
 
 	// Positional Lights
@@ -695,8 +698,15 @@ void main() {
 		}
 
 		light_blend_compute(light_base, light_color, color.rgb);
+#ifdef MODE_LIGHT_ONLY
+		light_only_alpha += light_color.a;
+#endif
 	}
 #endif
 
+#ifdef MODE_LIGHT_ONLY
+	color.a *= light_only_alpha;
+#endif
+
 	frag_color = color;
 }