Add AT_LIGHT_PASS builtin to canvas shaders

This one allows for complex shaders paired with a simple lighting shader to skip code that would otherwise be pointlessly (and wastefully) run during the light pass.

Depending on your game (number of items and lights), this can yield some performance gain.

drivers/gles3/shader_compiler_gles3.cpp

@@ -668,6 +668,7 @@ ShaderCompilerGLES3::ShaderCompilerGLES3() {
 	actions[VS::SHADER_CANVAS_ITEM].renames["PROJECTION_MATRIX"] = "projection_matrix";
 	actions[VS::SHADER_CANVAS_ITEM].renames["EXTRA_MATRIX"] == "extra_matrix";
 	actions[VS::SHADER_CANVAS_ITEM].renames["TIME"] = "time";
+	actions[VS::SHADER_CANVAS_ITEM].renames["AT_LIGHT_PASS"] = "at_light_pass";
 
 	actions[VS::SHADER_CANVAS_ITEM].renames["COLOR"] = "color";
 	actions[VS::SHADER_CANVAS_ITEM].renames["NORMAL"] = "normal";

drivers/gles3/shaders/canvas.glsl

@@ -59,6 +59,9 @@ out vec4 local_rot;
 out highp vec2 pos;
 #endif
 
+const bool at_light_pass = true;
+#else
+const bool at_light_pass = false;
 #endif
 
 
@@ -191,6 +194,9 @@ in highp vec2 pos;
 
 #endif
 
+const bool at_light_pass = true;
+#else
+const bool at_light_pass = false;
 #endif
 
 uniform mediump vec4 final_modulate;

servers/visual/shader_types.cpp

@@ -153,6 +153,7 @@ ShaderTypes::ShaderTypes() {
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["vertex"]["EXTRA_MATRIX"] = ShaderLanguage::TYPE_MAT4;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["vertex"]["TIME"] = ShaderLanguage::TYPE_FLOAT;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["vertex"]["PARTICLE_CUSTOM"] = ShaderLanguage::TYPE_VEC4;
+	shader_modes[VS::SHADER_CANVAS_ITEM].functions["vertex"]["AT_LIGHT_PASS"] = ShaderLanguage::TYPE_BOOL;
 
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["SRC_COLOR"] = ShaderLanguage::TYPE_VEC4;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["POSITION"] = ShaderLanguage::TYPE_VEC2;
@@ -166,6 +167,7 @@ ShaderTypes::ShaderTypes() {
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["SCREEN_UV"] = ShaderLanguage::TYPE_VEC2;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["POINT_COORD"] = ShaderLanguage::TYPE_VEC2;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["TIME"] = ShaderLanguage::TYPE_FLOAT;
+	shader_modes[VS::SHADER_CANVAS_ITEM].functions["fragment"]["AT_LIGHT_PASS"] = ShaderLanguage::TYPE_BOOL;
 
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["light"]["POSITION"] = ShaderLanguage::TYPE_VEC2;
 	shader_modes[VS::SHADER_CANVAS_ITEM].functions["light"]["NORMAL"] = ShaderLanguage::TYPE_VEC3;