From f10f301443862bca3cf3efdf11768f85fe734e9e Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 13 Dec 2020 23:20:41 +0300
Subject: [PATCH] Deferred renderer: support a background generation callback

---
 .../include/psemek/gfx/renderer/deferred.hpp    |  2 ++
 libs/gfx/source/renderer/deferred.cpp           | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/libs/gfx/include/psemek/gfx/renderer/deferred.hpp b/libs/gfx/include/psemek/gfx/renderer/deferred.hpp
index 45618d75..b4aa7147 100644
--- a/libs/gfx/include/psemek/gfx/renderer/deferred.hpp
+++ b/libs/gfx/include/psemek/gfx/renderer/deferred.hpp
@@ -10,6 +10,7 @@
 #include <psemek/geom/box.hpp>
 
 #include <psemek/util/pimpl.hpp>
+#include <psemek/util/function.hpp>
 
 namespace psemek::gfx
 {
@@ -95,6 +96,7 @@ namespace psemek::gfx
 			geom::camera const * camera;
 
 			std::optional<color_3f> clear_color;
+			util::function<void()> background_generator;
 
 			color_3f ambient;
 			std::vector<directional_light> directional_lights;
diff --git a/libs/gfx/source/renderer/deferred.cpp b/libs/gfx/source/renderer/deferred.cpp
index e7d0463d..de35b5d6 100644
--- a/libs/gfx/source/renderer/deferred.cpp
+++ b/libs/gfx/source/renderer/deferred.cpp
@@ -808,6 +808,7 @@ void main()
 
 		gfx::framebuffer g_framebuffer;
 		gfx::framebuffer occlusion_framebuffer;
+		gfx::framebuffer bg_framebuffer;
 		gfx::texture_2d g_buffer_texture[4];
 		gfx::texture_2d g_buffer_depth;
 
@@ -1183,8 +1184,11 @@ void main()
 			impl().g_framebuffer.depth(impl().g_buffer_depth);
 			impl().occlusion_framebuffer.depth(impl().g_buffer_depth);
 
+			impl().bg_framebuffer.color(impl().g_buffer_texture[1]);
+
 			impl().g_framebuffer.assert_complete();
 			impl().occlusion_framebuffer.assert_complete();
+			impl().bg_framebuffer.assert_complete();
 
 			impl().transparent_framebuffer.color(impl().g_buffer_texture[1]);
 			impl().transparent_framebuffer.depth(impl().g_buffer_depth);
@@ -1307,6 +1311,19 @@ void main()
 
 		gl::ClearBufferfv(gl::COLOR, 1, buffer_1_clear);
 
+		if (opts.background_generator)
+		{
+			impl().bg_framebuffer.bind();
+
+			gl::Enable(gl::DEPTH_TEST);
+			gl::DepthFunc(gl::LEQUAL);
+			gl::Disable(gl::BLEND);
+
+			opts.background_generator();
+
+			impl().g_framebuffer.bind();
+		}
+
 		gl::ClearDepth(1.f);
 		gl::Clear(gl::DEPTH_BUFFER_BIT);