Implement ability to render viewports directly to screen

7 files changed, 83 insertions, 2 deletions

diff --git a/drivers/dummy/rasterizer_dummy.h b/drivers/dummy/rasterizer_dummy.h
index 3b31da1dd7..253936ca34 100644
--- a/drivers/dummy/rasterizer_dummy.h
+++ b/drivers/dummy/rasterizer_dummy.h
@@ -692,6 +692,7 @@ public:
 	/* RENDER TARGET */
 
 	RID render_target_create() { return RID(); }
+	void render_target_set_position(RID p_render_target, int p_x, int p_y) {}
 	void render_target_set_size(RID p_render_target, int p_width, int p_height) {}
 	RID render_target_get_texture(RID p_render_target) const { return RID(); }
 	void render_target_set_external_texture(RID p_render_target, unsigned int p_texture_id) {}
diff --git a/drivers/gles2/rasterizer_canvas_gles2.cpp b/drivers/gles2/rasterizer_canvas_gles2.cpp
index 7232d2d95a..ee722e9d6c 100644
--- a/drivers/gles2/rasterizer_canvas_gles2.cpp
+++ b/drivers/gles2/rasterizer_canvas_gles2.cpp
@@ -113,9 +113,22 @@ void RasterizerCanvasGLES2::canvas_begin() {
 
 	state.canvas_shader.bind();
 	state.using_transparent_rt = false;
+	int viewport_x, viewport_y, viewport_width, viewport_height;
+
 	if (storage->frame.current_rt) {
 		glBindFramebuffer(GL_FRAMEBUFFER, storage->frame.current_rt->fbo);
 		state.using_transparent_rt = storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_TRANSPARENT];
+
+		if (storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+			// set Viewport and Scissor when rendering directly to screen
+			viewport_width = storage->frame.current_rt->width;
+			viewport_height = storage->frame.current_rt->height;
+			viewport_x = storage->frame.current_rt->x;
+			viewport_y = OS::get_singleton()->get_window_size().height - viewport_height - storage->frame.current_rt->y;
+			glScissor(viewport_x, viewport_y, viewport_width, viewport_height);
+			glViewport(viewport_x, viewport_y, viewport_width, viewport_height);
+			glEnable(GL_SCISSOR_TEST);
+		}
 	}
 
 	if (storage->frame.clear_request) {
@@ -179,6 +192,14 @@ void RasterizerCanvasGLES2::canvas_end() {
 		glDisableVertexAttribArray(i);
 	}
 
+	if (storage->frame.current_rt && storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+		//reset viewport to full window size
+		int viewport_width = OS::get_singleton()->get_window_size().width;
+		int viewport_height = OS::get_singleton()->get_window_size().height;
+		glViewport(0, 0, viewport_width, viewport_height);
+		glScissor(0, 0, viewport_width, viewport_height);
+	}
+
 	state.using_texture_rect = false;
 	state.using_skeleton = false;
 	state.using_ninepatch = false;
@@ -1192,6 +1213,11 @@ void RasterizerCanvasGLES2::_canvas_item_render_commands(Item *p_item, Item *cur
 
 void RasterizerCanvasGLES2::_copy_screen(const Rect2 &p_rect) {
 
+	if (storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+		ERR_PRINT_ONCE("Cannot use screen texture copying in render target set to render direct to screen");
+		return;
+	}
+
 	if (storage->frame.current_rt->copy_screen_effect.color == 0) {
 		ERR_EXPLAIN("Can't use screen texture copying in a render target configured without copy buffers");
 		ERR_FAIL();
diff --git a/drivers/gles2/rasterizer_scene_gles2.cpp b/drivers/gles2/rasterizer_scene_gles2.cpp
index 55257ab1c5..75885f5bca 100644
--- a/drivers/gles2/rasterizer_scene_gles2.cpp
+++ b/drivers/gles2/rasterizer_scene_gles2.cpp
@@ -2694,6 +2694,7 @@ void RasterizerSceneGLES2::render_scene(const Transform &p_cam_transform, const
 	Environment *env = NULL;
 
 	int viewport_width, viewport_height;
+	int viewport_x, viewport_y;
 	bool probe_interior = false;
 	bool reverse_cull = false;
 
@@ -2733,6 +2734,13 @@ void RasterizerSceneGLES2::render_scene(const Transform &p_cam_transform, const
 
 		viewport_width = storage->frame.current_rt->width;
 		viewport_height = storage->frame.current_rt->height;
+		viewport_x = storage->frame.current_rt->x;
+
+		if (storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+			viewport_y = OS::get_singleton()->get_window_size().height - viewport_height - storage->frame.current_rt->y;
+		} else {
+			viewport_y = storage->frame.current_rt->y;
+		}
 	}
 
 	state.used_screen_texture = false;
@@ -2798,7 +2806,13 @@ void RasterizerSceneGLES2::render_scene(const Transform &p_cam_transform, const
 	// other stuff
 
 	glBindFramebuffer(GL_FRAMEBUFFER, current_fb);
-	glViewport(0, 0, viewport_width, viewport_height);
+	glViewport(viewport_x, viewport_y, viewport_width, viewport_height);
+
+	if (storage->frame.current_rt && storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+
+		glScissor(viewport_x, viewport_y, viewport_width, viewport_height);
+		glEnable(GL_SCISSOR_TEST);
+	}
 
 	glDepthFunc(GL_LEQUAL);
 	glDepthMask(GL_TRUE);
@@ -2832,6 +2846,10 @@ void RasterizerSceneGLES2::render_scene(const Transform &p_cam_transform, const
 
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
+	if (storage->frame.current_rt && storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_DIRECT_TO_SCREEN]) {
+		glDisable(GL_SCISSOR_TEST);
+	}
+
 	glVertexAttrib4f(VS::ARRAY_COLOR, 1, 1, 1, 1);
 
 	glBlendEquation(GL_FUNC_ADD);
diff --git a/drivers/gles2/rasterizer_storage_gles2.cpp b/drivers/gles2/rasterizer_storage_gles2.cpp
index d709056709..c610f31bc1 100644
--- a/drivers/gles2/rasterizer_storage_gles2.cpp
+++ b/drivers/gles2/rasterizer_storage_gles2.cpp
@@ -4568,9 +4568,16 @@ void RasterizerStorageGLES2::instance_remove_dependency(RID p_base, RasterizerSc
 
 void RasterizerStorageGLES2::_render_target_allocate(RenderTarget *rt) {
 
+	// do not allocate a render target with no size
 	if (rt->width <= 0 || rt->height <= 0)
 		return;
 
+	// do not allocate a render target that is attached to the screen
+	if (rt->flags[RENDER_TARGET_DIRECT_TO_SCREEN]) {
+		rt->fbo = RasterizerStorageGLES2::system_fbo;
+		return;
+	}
+
 	GLuint color_internal_format;
 	GLuint color_format;
 	GLuint color_type = GL_UNSIGNED_BYTE;
@@ -4779,6 +4786,10 @@ void RasterizerStorageGLES2::_render_target_allocate(RenderTarget *rt) {
 
 void RasterizerStorageGLES2::_render_target_clear(RenderTarget *rt) {
 
+	// there is nothing to clear when DIRECT_TO_SCREEN is used
+	if (rt->flags[RENDER_TARGET_DIRECT_TO_SCREEN])
+		return;
+
 	if (rt->fbo) {
 		glDeleteFramebuffers(1, &rt->fbo);
 		glDeleteTextures(1, &rt->color);
@@ -4873,6 +4884,15 @@ RID RasterizerStorageGLES2::render_target_create() {
 	return render_target_owner.make_rid(rt);
 }
 
+void RasterizerStorageGLES2::render_target_set_position(RID p_render_target, int p_x, int p_y) {
+
+	RenderTarget *rt = render_target_owner.getornull(p_render_target);
+	ERR_FAIL_COND(!rt);
+
+	rt->x = p_x;
+	rt->y = p_y;
+}
+
 void RasterizerStorageGLES2::render_target_set_size(RID p_render_target, int p_width, int p_height) {
 
 	RenderTarget *rt = render_target_owner.getornull(p_render_target);
@@ -5002,6 +5022,14 @@ void RasterizerStorageGLES2::render_target_set_flag(RID p_render_target, RenderT
 	RenderTarget *rt = render_target_owner.getornull(p_render_target);
 	ERR_FAIL_COND(!rt);
 
+	// When setting DIRECT_TO_SCREEN, you need to clear before the value is set, but allocate after as
+	// those functions change how they operate depending on the value of DIRECT_TO_SCREEN
+	if (p_flag == RENDER_TARGET_DIRECT_TO_SCREEN && p_value != rt->flags[RENDER_TARGET_DIRECT_TO_SCREEN]) {
+		_render_target_clear(rt);
+		rt->flags[p_flag] = p_value;
+		_render_target_allocate(rt);
+	}
+
 	rt->flags[p_flag] = p_value;
 
 	switch (p_flag) {
diff --git a/drivers/gles2/rasterizer_storage_gles2.h b/drivers/gles2/rasterizer_storage_gles2.h
index 3134082e2a..af57aa3d9b 100644
--- a/drivers/gles2/rasterizer_storage_gles2.h
+++ b/drivers/gles2/rasterizer_storage_gles2.h
@@ -1175,7 +1175,7 @@ public:
 			}
 		} external;
 
-		int width, height;
+		int x, y, width, height;
 
 		bool flags[RENDER_TARGET_FLAG_MAX];
 
@@ -1192,6 +1192,8 @@ public:
 				multisample_color(0),
 				multisample_depth(0),
 				multisample_active(false),
+				x(0),
+				y(0),
 				width(0),
 				height(0),
 				used_in_frame(false),
@@ -1209,6 +1211,7 @@ public:
 	void _render_target_allocate(RenderTarget *rt);
 
 	virtual RID render_target_create();
+	virtual void render_target_set_position(RID p_render_target, int p_x, int p_y);
 	virtual void render_target_set_size(RID p_render_target, int p_width, int p_height);
 	virtual RID render_target_get_texture(RID p_render_target) const;
 	virtual void render_target_set_external_texture(RID p_render_target, unsigned int p_texture_id);
diff --git a/drivers/gles3/rasterizer_storage_gles3.cpp b/drivers/gles3/rasterizer_storage_gles3.cpp
index 661be28e6b..247b30811e 100644
--- a/drivers/gles3/rasterizer_storage_gles3.cpp
+++ b/drivers/gles3/rasterizer_storage_gles3.cpp
@@ -7268,6 +7268,10 @@ RID RasterizerStorageGLES3::render_target_create() {
 	return render_target_owner.make_rid(rt);
 }
 
+void RasterizerStorageGLES3::render_target_set_position(RID p_render_target, int p_x, int p_y) {
+	//only used in GLES2
+}
+
 void RasterizerStorageGLES3::render_target_set_size(RID p_render_target, int p_width, int p_height) {
 
 	RenderTarget *rt = render_target_owner.getornull(p_render_target);
diff --git a/drivers/gles3/rasterizer_storage_gles3.h b/drivers/gles3/rasterizer_storage_gles3.h
index a4cc84ef02..99aa34e1ce 100644
--- a/drivers/gles3/rasterizer_storage_gles3.h
+++ b/drivers/gles3/rasterizer_storage_gles3.h
@@ -1394,6 +1394,7 @@ public:
 	void _render_target_allocate(RenderTarget *rt);
 
 	virtual RID render_target_create();
+	virtual void render_target_set_position(RID p_render_target, int p_x, int p_y);
 	virtual void render_target_set_size(RID p_render_target, int p_width, int p_height);
 	virtual RID render_target_get_texture(RID p_render_target) const;
 	virtual void render_target_set_external_texture(RID p_render_target, unsigned int p_texture_id);