Fix wrong usage of cockpit depth buffer

The root issue of #976 was that the code that reset the depth buffer of
the scene framebuffer was actually setting the depth buffer of the bloom
framebuffer since that didn't get reset properly. To fix this I
introduced a system in our GL_state which keeps track of a stack of
"bound" framebuffers which allows us to return to the previous
framebuffer with a simple function call.

I also added support for GL_KHR_debug since that help me while debugging
which texture was in use. In the future I'll probably extend that to
other areas of the OpenGL code as needed.

This fixes #976.

Author: asarium

code/graphics/opengl/gropengldraw.cpp

@@ -1576,7 +1576,8 @@ void opengl_setup_scene_textures()
 
 	// create framebuffer
 	glGenFramebuffers(1, &Scene_framebuffer);
-	glBindFramebuffer(GL_FRAMEBUFFER, Scene_framebuffer);
+	GL_state.BindFrameBuffer(Scene_framebuffer);
+	glObjectLabelKHR(GL_FRAMEBUFFER, Scene_framebuffer, -1, "Scene framebuffer");
 
 	// setup main render texture
 
@@ -1596,6 +1597,7 @@ void opengl_setup_scene_textures()
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
 
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, Scene_color_texture, 0);
+	glObjectLabelKHR(GL_TEXTURE, Scene_color_texture, -1, "Scene color texture");
 
 	// setup low dynamic range color texture
 	glGenTextures(1, &Scene_ldr_texture);
@@ -1611,6 +1613,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_ldr_texture, -1, "Scene LDR texture");
 
 	// setup position render texture
 	glGenTextures(1, &Scene_position_texture);
@@ -1626,6 +1629,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_position_texture, -1, "Scene Position texture");
 
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, Scene_position_texture, 0);
 
@@ -1643,6 +1647,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_normal_texture, -1, "Scene Normal texture");
 
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, Scene_normal_texture, 0);
 
@@ -1660,6 +1665,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_specular_texture, -1, "Scene Specular texture");
 
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT3, GL_TEXTURE_2D, Scene_specular_texture, 0);
 
@@ -1678,6 +1684,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_luminance_texture, -1, "Scene Luminance texture");
 
 	// setup effect texture
 
@@ -1694,6 +1701,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, Scene_texture_width, Scene_texture_height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_effect_texture, -1, "Scene Effect texture");
 
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT4, GL_TEXTURE_2D, Scene_effect_texture, 0);
 
@@ -1712,6 +1720,8 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_NONE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, Scene_texture_width, Scene_texture_height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Cockpit_depth_texture, -1, "Cockpit depth texture");
+
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, Cockpit_depth_texture, 0);
 	gr_zbuffer_set(GR_ZBUFF_FULL);
 	glClear(GL_DEPTH_BUFFER_BIT);
@@ -1731,6 +1741,7 @@ void opengl_setup_scene_textures()
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_NONE);
 
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, Scene_texture_width, Scene_texture_height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
+	glObjectLabelKHR(GL_TEXTURE, Scene_depth_texture, -1, "Scene depth texture");
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, Scene_depth_texture, 0);
 
 	//setup main stencil buffer
@@ -1742,7 +1753,7 @@ void opengl_setup_scene_textures()
 	glReadBuffer(GL_COLOR_ATTACHMENT0);
 
 	if ( opengl_check_framebuffer() ) {
-		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+		GL_state.BindFrameBuffer(0);
 		glDeleteFramebuffers(1, &Scene_framebuffer);
 		Scene_framebuffer = 0;
 
@@ -1779,7 +1790,7 @@ void opengl_setup_scene_textures()
     if (Cmdline_fb_thrusters || Cmdline_fb_explosions) 
     {
         glGenFramebuffers(1, &Distortion_framebuffer);
-        glBindFramebuffer(GL_FRAMEBUFFER, Distortion_framebuffer);
+		GL_state.BindFrameBuffer(Distortion_framebuffer);
 
         glGenTextures(2, Distortion_texture);
 
@@ -1810,7 +1821,7 @@ void opengl_setup_scene_textures()
 
 
 	if ( opengl_check_framebuffer() ) {
-		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+		GL_state.BindFrameBuffer(0);
 		glDeleteFramebuffers(1, &Distortion_framebuffer);
 		Distortion_framebuffer = 0;
 
@@ -1829,7 +1840,7 @@ void opengl_setup_scene_textures()
 		return;
 	}
 
-	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	GL_state.BindFrameBuffer(0);
 
 	Scene_texture_initialized = 1;
 	Scene_framebuffer_in_frame = false;
@@ -1902,7 +1913,9 @@ void gr_opengl_scene_texture_begin()
 
 	GR_DEBUG_SCOPE("Begin scene texture");
 
-	glBindFramebuffer(GL_FRAMEBUFFER, Scene_framebuffer);
+	GL_state.PushFramebufferState();
+	GL_state.BindFrameBuffer(Scene_framebuffer);
+	//glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, Scene_depth_texture, 0);
 
 	if (GL_rendering_to_texture)
 	{
@@ -1967,7 +1980,7 @@ void gr_opengl_scene_texture_end()
 		GLboolean blend = GL_state.Blend(GL_FALSE);
 		GLboolean cull = GL_state.CullFace(GL_FALSE);
 
-		glBindFramebuffer(GL_FRAMEBUFFER, opengl_get_rtt_framebuffer());
+		GL_state.PopFramebufferState();
 
 		GL_state.Texture.SetActiveUnit(0);
 		GL_state.Texture.SetTarget(GL_TEXTURE_2D);
@@ -2046,6 +2059,8 @@ void gr_opengl_deferred_lighting_begin()
 	if ( Cmdline_no_deferred_lighting)
 		return;
 
+	GR_DEBUG_SCOPE("Deferred lighting begin");
+
 	Deferred_lighting = true;
 	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 
@@ -2057,6 +2072,9 @@ void gr_opengl_deferred_lighting_end()
 {
 	if(!Deferred_lighting)
 		return;
+
+	GR_DEBUG_SCOPE("Deferred lighting end");
+
 	Deferred_lighting = false;
 	glDrawBuffer(GL_COLOR_ATTACHMENT0);
 
@@ -2071,6 +2089,7 @@ extern float static_tube_factor;
 
 void gr_opengl_deferred_lighting_finish()
 {
+	GR_DEBUG_SCOPE("Deferred lighting finish");
 	TRACE_SCOPE(tracing::ApplyLights);
 
 	if ( Cmdline_no_deferred_lighting ) {
@@ -2122,6 +2141,8 @@ void gr_opengl_deferred_lighting_finish()
 
 	for(int i = 0; i < Num_lights; ++i)
 	{
+		GR_DEBUG_SCOPE("Deferred apply single light");
+
 		light *l = &lights_copy[i];
 		Current_shader->program->Uniforms.setUniformi( "lightType", 0 );
 		switch(l->type)
@@ -2209,6 +2230,7 @@ void gr_opengl_deferred_lighting_finish()
 	GL_state.Texture.Enable(Scene_luminance_texture);
 
 	GL_state.SetAlphaBlendMode( ALPHA_BLEND_ADDITIVE );
+	GL_state.DepthMask(GL_FALSE);
 
 	opengl_draw_textured_quad(0.0f, 0.0f, 0.0f, Scene_texture_v_scale, (float)gr_screen.max_w, (float)gr_screen.max_h, Scene_texture_u_scale, 0.0f);
 
@@ -2270,7 +2292,9 @@ void gr_opengl_update_distortion()
 	GLboolean cull = GL_state.CullFace(GL_FALSE);
 
 	opengl_shader_set_passthrough(true, false);
-	glBindFramebuffer(GL_FRAMEBUFFER, Distortion_framebuffer);
+
+	GL_state.PushFramebufferState();
+	GL_state.BindFrameBuffer(Distortion_framebuffer);
 	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, Distortion_texture[!Distortion_switch], 0);
 	glDrawBuffer(GL_COLOR_ATTACHMENT0);
 
@@ -2339,7 +2363,7 @@ void gr_opengl_update_distortion()
 	Distortion_switch = !Distortion_switch;
 
 	// reset state
-	glBindFramebuffer(GL_FRAMEBUFFER, Scene_framebuffer);
+	GL_state.PopFramebufferState();
 
 	glViewport(0,0,gr_screen.max_w,gr_screen.max_h);
 

code/graphics/opengl/gropenglpostprocessing.cpp

@@ -103,13 +103,15 @@ void opengl_post_pass_bloom()
 	// we need the scissor test disabled
 	GLboolean scissor_test = GL_state.ScissorTest(GL_FALSE);
 
+	GL_state.PushFramebufferState();
+
 	// ------  begin bright pass ------
 	int width, height;
 	{
 		GR_DEBUG_SCOPE("Bloom bright pass");
 		TRACE_SCOPE(tracing::BloomBrightPass);
 
-		glBindFramebuffer(GL_FRAMEBUFFER, Bloom_framebuffer);
+		GL_state.BindFrameBuffer(Bloom_framebuffer);
 		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, Bloom_textures[0], 0);
 
 		// width and height are 1/2 for the bright pass
@@ -224,7 +226,8 @@ void gr_opengl_post_process_begin()
 		return;
 	}
 
-	glBindFramebuffer(GL_FRAMEBUFFER, Post_framebuffer_id[0]);
+	GL_state.PushFramebufferState();
+	GL_state.BindFrameBuffer(Post_framebuffer_id[0]);
 
 	glDrawBuffer(GL_COLOR_ATTACHMENT0);
 
@@ -383,6 +386,8 @@ void gr_opengl_post_process_end()
 	// do tone mapping
 	opengl_post_pass_tonemap();
 
+	GL_state.PopFramebufferState();
+
     // Do FXAA
     if (Cmdline_fxaa && !fxaa_unavailable && !GL_rendering_to_texture) {
         opengl_post_pass_fxaa();
@@ -394,8 +399,8 @@ void gr_opengl_post_process_end()
 	GR_DEBUG_SCOPE("Draw post effects");
 	TRACE_SCOPE(tracing::DrawPostEffects);
 
-	// now write to the on-screen buffer
-	glBindFramebuffer(GL_FRAMEBUFFER, opengl_get_rtt_framebuffer());
+	// now write to the previous buffer
+	GL_state.PopFramebufferState();
 
 	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
 	glClear(GL_COLOR_BUFFER_BIT);
@@ -432,7 +437,7 @@ void gr_opengl_post_process_end()
 	}
 
 	// now render it to the screen ...
-	glBindFramebuffer(GL_FRAMEBUFFER,0);
+	GL_state.BindFrameBuffer(0);
 	GL_state.Texture.SetActiveUnit(0);
 	GL_state.Texture.SetTarget(GL_TEXTURE_2D);
 	//GL_state.Texture.Enable(Scene_color_texture);
@@ -585,6 +590,7 @@ void gr_opengl_post_process_set_defaults()
 extern GLuint Cockpit_depth_texture;
 void gr_opengl_post_process_save_zbuffer()
 {
+	GR_DEBUG_SCOPE("Save z-Buffer");
 	if (Post_initialized)
 	{
 		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, Cockpit_depth_texture, 0);
@@ -870,7 +876,7 @@ void opengl_setup_bloom_textures()
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, MAX_MIP_BLUR_LEVELS-1);
 	}
 
-	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	GL_state.BindFrameBuffer(0);
 }
 
 // generate and test the framebuffer and textures that we are going to use
@@ -896,7 +902,7 @@ static bool opengl_post_init_framebuffer()
 		int size = (Cmdline_shadow_quality == 2 ? 1024 : 512);
 
 		glGenFramebuffers(1, &Post_shadow_framebuffer_id);
-		glBindFramebuffer(GL_FRAMEBUFFER, Post_shadow_framebuffer_id);
+		GL_state.BindFrameBuffer(Post_shadow_framebuffer_id);
 
 		glGenTextures(1, &Post_shadow_texture_id);
 
@@ -947,7 +953,7 @@ static bool opengl_post_init_framebuffer()
 		glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, Post_shadow_depth_texture_id, 0);
 	}
 
-	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	GL_state.BindFrameBuffer(0);
 
 	rval = true;
 

code/graphics/opengl/gropenglstate.cpp

@@ -180,6 +180,11 @@ void opengl_state::init()
 
 	current_program = 0;
 	glUseProgram(0);
+
+	current_framebuffer = 0;
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	framebuffer_stack.clear();
 }
 
 GLboolean opengl_state::Blend(GLint state)
@@ -508,6 +513,23 @@ void opengl_state::UseProgram(GLuint program)
 bool opengl_state::IsCurrentProgram(GLuint program) {
 	return current_program == program;
 }
+void opengl_state::BindFrameBuffer(GLuint name) {
+	if (current_framebuffer != name) {
+		glBindFramebuffer(GL_FRAMEBUFFER, name);
+		current_framebuffer = name;
+	}
+}
+void opengl_state::PushFramebufferState() {
+	framebuffer_stack.push_back(current_framebuffer);
+}
+void opengl_state::PopFramebufferState() {
+	Assertion(framebuffer_stack.size() > 0, "Tried to pop the framebuffer state stack while it was empty!");
+
+	auto restoreBuffer = framebuffer_stack.back();
+	framebuffer_stack.pop_back();
+
+	BindFrameBuffer(restoreBuffer);
+}
 
 opengl_array_state::~opengl_array_state()
 {

code/graphics/opengl/gropenglstate.h

@@ -173,6 +173,10 @@ class opengl_state
         gr_stencil_type Current_stencil_type;
 
 		GLuint current_program;
+
+		// The framebuffer state actually consists of draw and read buffers but we only use both at the same time
+		GLuint current_framebuffer;
+		SCP_vector<GLuint> framebuffer_stack;
 	public:
 		opengl_state() {}
 		~opengl_state() {}
@@ -213,6 +217,11 @@ class opengl_state
 
 		void UseProgram(GLuint program);
 		bool IsCurrentProgram(GLuint program);
+
+		void BindFrameBuffer(GLuint name);
+
+		void PushFramebufferState();
+		void PopFramebufferState();
 };
 
 inline GLenum opengl_state::FrontFaceValue(GLenum new_val)
@@ -277,5 +286,4 @@ extern opengl_state GL_state;
 void gr_opengl_clear_states();
 void opengl_setup_render_states(int &r,int &g,int &b,int &alpha, int &tmap_type, int flags, int is_scaler = 0);
 
-
 #endif	// _GROPENGLSTATE_H