From 250c108e97f8c72ca2d35a0ba03fd3f7b0359a40 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackmchristensen.com>
Date: Wed, 14 Aug 2024 16:40:51 -0400
Subject: [PATCH] Implement HDR and gamma correction in post shader pass

---
 imgui.ini                  |  8 ++++----
 shaders/fragment.glsl      |  6 ++++--
 shaders/quad_fragment.glsl | 17 +++++++++++------
 shaders/quad_vertex.glsl   |  6 +++---
 source/fbo.cpp             |  2 +-
 source/scene.cpp           |  1 -
 6 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/imgui.ini b/imgui.ini
index 29d1fe7..87f08b5 100644
--- a/imgui.ini
+++ b/imgui.ini
@@ -5,7 +5,7 @@ Collapsed=0
 
 [Window][Terrain Controls]
 Pos=0,19
-Size=1498,94
+Size=1280,94
 Collapsed=0
 DockId=0x00000001,0
 
@@ -19,17 +19,17 @@ Collapsed=0
 
 [Window][TerraVisor]
 Pos=0,0
-Size=1498,720
+Size=1280,720
 Collapsed=0
 
 [Window][Scene Window]
 Pos=0,115
-Size=1498,605
+Size=1280,605
 Collapsed=0
 DockId=0x00000002,0
 
 [Docking][Data]
-DockSpace   ID=0x6F42A598 Window=0xE80F322C Pos=0,19 Size=1498,701 Split=Y Selected=0x9F2D9299
+DockSpace   ID=0x6F42A598 Window=0xE80F322C Pos=0,19 Size=1280,701 Split=Y Selected=0x9F2D9299
   DockNode  ID=0x00000001 Parent=0x6F42A598 SizeRef=1280,94 Selected=0xF69494A7
   DockNode  ID=0x00000002 Parent=0x6F42A598 SizeRef=1280,605 CentralNode=1 Selected=0x9F2D9299
 
diff --git a/shaders/fragment.glsl b/shaders/fragment.glsl
index e6ae42a..fdf2154 100644
--- a/shaders/fragment.glsl
+++ b/shaders/fragment.glsl
@@ -1,4 +1,6 @@
 #version 430
+precision highp float;
+
 layout(binding = 0) uniform sampler2D diffuse_tex; 
 layout(location = 1) uniform float time;
 
@@ -31,7 +33,7 @@ in VertexData
     vec3 nw;   //world-space normal vector
 } inData;   //block is named 'inData'
 
-out vec4 fragcolor; //the output color for this fragment    
+out vec4 frag_color; //the output color for this fragment    
 
 void main(void)
 {   
@@ -54,6 +56,6 @@ void main(void)
     // vec4 specular_term = atten*ks*Ls*pow(max(0.0, dot(rw, vw)), shininess);
 
     // fragcolor = ambient_term + diffuse_term + specular_term;
-    fragcolor = vec4(0.0, 0.0, 1.0, 1.0);
+    frag_color = vec4(0.45f, 0.82f, 0.52f, 1.0f);
 }
 
diff --git a/shaders/quad_fragment.glsl b/shaders/quad_fragment.glsl
index 7a19693..58d6f30 100644
--- a/shaders/quad_fragment.glsl
+++ b/shaders/quad_fragment.glsl
@@ -1,12 +1,17 @@
-#version 330 core
-out vec4 FragColor;
+#version 430
+precision highp float;
 
-in vec2 TexCoord;
+out vec4 frag_color;
 
-uniform sampler2D screenTexture;
+in vec2 tex_coords;
+
+uniform sampler2D screen_texture;
 
 void main()
 {
-    FragColor = texture(screenTexture, TexCoord);
-    //FragColor = vec4(vec3(1.0 - texture(screenTexture, TexCoord)), 1.0);
+    vec3 hdr_color = texture(screen_texture, tex_coords).rgb;
+    vec3 tone_mapped_color = hdr_color / (hdr_color + vec3(1.0));
+    tone_mapped_color = pow(tone_mapped_color, vec3(1.0/2.2));
+
+    frag_color = vec4(tone_mapped_color, 1.0);
 }
diff --git a/shaders/quad_vertex.glsl b/shaders/quad_vertex.glsl
index 7a4f575..2310e72 100644
--- a/shaders/quad_vertex.glsl
+++ b/shaders/quad_vertex.glsl
@@ -1,12 +1,12 @@
-#version 330 core
+#version 430
 layout(location = 0) in vec3 pos_attrib; //this variable holds the position of mesh vertices
 layout(location = 1) in vec2 tex_coord_attrib;
 layout(location = 2) in vec3 normal_attrib;  
 
-out vec2 TexCoord;
+out vec2 tex_coords;
 
 void main()
 {
     gl_Position = vec4(pos_attrib.xy, 0.0, 1.0);
-    TexCoord = tex_coord_attrib;
+    tex_coords = tex_coord_attrib;
 }
diff --git a/source/fbo.cpp b/source/fbo.cpp
index 7d90cfc..6062b67 100644
--- a/source/fbo.cpp
+++ b/source/fbo.cpp
@@ -18,7 +18,7 @@ void FBO::Init(int width, int height) {
     // Generate the color texture
     glGenTextures(1, &color_texture_id_);
     glBindTexture(GL_TEXTURE_2D, color_texture_id_);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, nullptr);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, width, height, 0, GL_RGBA, GL_FLOAT, nullptr);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
diff --git a/source/scene.cpp b/source/scene.cpp
index b480f8d..0298408 100644
--- a/source/scene.cpp
+++ b/source/scene.cpp
@@ -153,7 +153,6 @@ void Scene::Display(GLFWwindow* window) {
 
     fbo_.Unbind();
 
-    // post_fbo_ currently renders with a nasty artifact. Need to fix
     post_fbo_.Bind();
     glDisable(GL_DEPTH_TEST);