Use transparent framebuffer only when set to transparent, closes #21827

drivers/gles2/rasterizer_canvas_gles2.cpp

@@ -112,9 +112,11 @@ void RasterizerCanvasGLES2::_set_uniforms() {
 void RasterizerCanvasGLES2::canvas_begin() {
 
 	state.canvas_shader.bind();
+	bool transparent = false;
 	if (storage->frame.current_rt) {
 		glBindFramebuffer(GL_FRAMEBUFFER, storage->frame.current_rt->fbo);
 		glColorMask(1, 1, 1, 1);
+		transparent = storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_TRANSPARENT];
 	}
 
 	if (storage->frame.clear_request) {
@@ -122,11 +124,13 @@ void RasterizerCanvasGLES2::canvas_begin() {
 		glClearColor(storage->frame.clear_request_color.r,
 				storage->frame.clear_request_color.g,
 				storage->frame.clear_request_color.b,
-				storage->frame.clear_request_color.a);
+				transparent ? storage->frame.clear_request_color.a : 1.0);
 		glClear(GL_COLOR_BUFFER_BIT);
 		storage->frame.clear_request = false;
 	}
 
+	glColorMask(1, 1, 1, transparent ? 1 : 0);
+
 	/*
 	if (storage->frame.current_rt) {
 		glBindFramebuffer(GL_FRAMEBUFFER, storage->frame.current_rt->fbo);
@@ -182,6 +186,7 @@ void RasterizerCanvasGLES2::canvas_end() {
 	state.using_texture_rect = false;
 	state.using_skeleton = false;
 	state.using_ninepatch = false;
+	glColorMask(1, 1, 1, 1);
 }
 
 RasterizerStorageGLES2::Texture *RasterizerCanvasGLES2::_bind_canvas_texture(const RID &p_texture, const RID &p_normal_map) {

drivers/gles3/rasterizer_canvas_gles3.cpp

@@ -146,10 +146,15 @@ void RasterizerCanvasGLES3::canvas_begin() {
 
 	if (storage->frame.current_rt && storage->frame.clear_request) {
 		// a clear request may be pending, so do it
+		bool transparent = storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_TRANSPARENT];
 
-		glClearColor(storage->frame.clear_request_color.r, storage->frame.clear_request_color.g, storage->frame.clear_request_color.b, storage->frame.clear_request_color.a);
+		glClearColor(storage->frame.clear_request_color.r,
+				storage->frame.clear_request_color.g,
+				storage->frame.clear_request_color.b,
+				transparent ? storage->frame.clear_request_color.a : 1.0);
 		glClear(GL_COLOR_BUFFER_BIT);
 		storage->frame.clear_request = false;
+		glColorMask(1, 1, 1, transparent ? 1 : 0);
 	}
 
 	reset_canvas();
@@ -193,6 +198,7 @@ void RasterizerCanvasGLES3::canvas_end() {
 
 	glBindVertexArray(0);
 	glBindBufferBase(GL_UNIFORM_BUFFER, 0, 0);
+	glColorMask(1, 1, 1, 1);
 
 	state.using_texture_rect = false;
 	state.using_ninepatch = false;