From c99ecda7bed596922125f6b1ef1ef2ae8f27703e Mon Sep 17 00:00:00 2001
From: Patrick
Date: Fri, 26 Mar 2021 19:36:35 +0100
Subject: SSSSS comments

---
 shaders/fbo_frag.glsl        | 36 ++++--------------------------------
 shaders/fbo_vert.glsl        |  1 +
 shaders/frag_irradiance.glsl | 30 +++++++++---------------------
 shaders/frag_shadowmap.glsl  |  2 +-
 shaders/vert_irradiance.glsl | 44 +++++++++++++-------------------------------
 shaders/vert_shadowmap.glsl  |  1 +
 6 files changed, 29 insertions(+), 85 deletions(-)

(limited to 'shaders')

diff --git a/shaders/fbo_frag.glsl b/shaders/fbo_frag.glsl
index 1102992..f92483e 100644
--- a/shaders/fbo_frag.glsl
+++ b/shaders/fbo_frag.glsl
@@ -11,45 +11,17 @@ uniform int renderState;
 uniform vec2 samplePositions[13];
 uniform vec3 sampleWeights[13];
 
-vec4 blur(sampler2D tex, vec2 uv, vec2 res) {
-  float Pi = 6.28318530718; // Pi*2
-    
-  // GAUSSIAN BLUR SETTINGS {{{
-  float Directions = 16.0; // BLUR DIRECTIONS (Default 16.0 - More is better but slower)
-  float Quality = 4.0; // BLUR QUALITY (Default 4.0 - More is better but slower)
-  float Size = 8.0; // BLUR SIZE (Radius)
-  // GAUSSIAN BLUR SETTINGS }}}
-  
-  vec2 Radius = Size/res;
-  
-  // Pixel colour
-  vec4 Color = texture(tex, uv);
-  
-  // Blur calculations
-  for( float d=0.0; d<Pi; d+=Pi/Directions) {
-    for(float i=1.0/Quality; i<=1.0; i+=1.0/Quality) {
-      Color += texture( tex, uv+vec2(cos(d),sin(d))*Radius*i);		
-    }
-  }
-  
-  // Output to screen
-  Color /= Quality * Directions - 15.0;
-  return Color;
-}
-
 void main()
 {
     if (renderState == 0) {
-        FragColor = blur(shadowmapTexture, TexCoords, vec2(screenWidth, screenHeight));
-    }
-    else if (renderState == 1) {
         FragColor = texture(shadowmapTexture, TexCoords);
     }
-    // stencil buffer
-    else if (renderState == 2) {
+    else if (renderState == 1) {
         FragColor = texture(irradianceTexture, TexCoords);
     }
-    else if (renderState == 3) {
+    else if (renderState == 2) {
+        // sample calculated irradiance
+        // using Gaussian kernel to approximate light spread
         vec4 result = vec4(0, 0, 0, 1);
         for (int i = 0; i < 13; i++) {
             vec2 sampleCoords = TexCoords + samplePositions[i] * vec2(1.0/screenWidth, 1.0/screenHeight);
diff --git a/shaders/fbo_vert.glsl b/shaders/fbo_vert.glsl
index fb80df5..0cf6138 100644
--- a/shaders/fbo_vert.glsl
+++ b/shaders/fbo_vert.glsl
@@ -6,6 +6,7 @@ out vec2 TexCoords;
 
 void main()
 {
+    // this is just a plane that covers the screen
     gl_Position = vec4(aPos.x, aPos.y, 0.0, 1.0); 
     TexCoords = aTexCoords;
 }
diff --git a/shaders/frag_irradiance.glsl b/shaders/frag_irradiance.glsl
index 1bcbc99..b985acf 100644
--- a/shaders/frag_irradiance.glsl
+++ b/shaders/frag_irradiance.glsl
@@ -17,11 +17,9 @@ uniform int renderState;
 uniform float powBase;
 uniform float powFactor;
 
-uniform float translucencySampleVariances[6];
-uniform vec3 translucencySampleWeights[6];
-
 void main()
 {
+  // phong lighting
   vec3 norm = normalize(Normal);
   vec3 lightDir = normalize(lightPos - FragPos);
 
@@ -37,30 +35,20 @@ void main()
   float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
   vec3 specular = specularStrength * spec * lightColor;
 
-  //float distanceToBackside = length(clamp(FragPos - Backside, vec3(0), vec3(1000)));
-  float distanceToBackside = length(FragPos - Backside);
-  //distanceToBackside = distance(Backside, LocalPos);
   vec3 result = (ambient + diffuse + specular) * objectColor;
 
-  if (renderState == 3) {
+  // thickness
+  float distanceToBackside = length(FragPos - Backside);
+
+  if (renderState == 2) {
     if (distanceToBackside != 0) {
+      // add translucency by amplifying color inverse to the thickness
+      // (1 - diff) is part of the irradiance term,
+      // if the light hits the object straight at 90°
+      // most light is received
       result += objectColor * pow(powBase, powFactor / pow(distanceToBackside, 0.6)) * transmittanceScale * (1 - diff);
-      // vec3 translucency = vec3(0);
-      // for (int i = 0; i < 6; i++) {
-      //   translucency += objectColor * translucencySampleWeights[i] * exp(-pow(distanceToBackside, 2.0) / translucencySampleVariances[i]);
-      // }
-
-      // result += translucency * transmittanceScale;
     }
   }
-      //result += objectColor * pow(powBase, -pow(distanceToBackside, 2)) * transmittanceScale * (1 - diff);
-  // if (renderState == 3) {
-  //   //result = Backside;
-  //   //result = LocalPos;
-  //   result = vec3(distanceToBackside);
-  // }
-
     
   FragColor = vec4(result, 1.0f);
-  //FragColor = vec4(vec3(distanceToBackside), 1);
 }
diff --git a/shaders/frag_shadowmap.glsl b/shaders/frag_shadowmap.glsl
index 2011f82..38a01b6 100644
--- a/shaders/frag_shadowmap.glsl
+++ b/shaders/frag_shadowmap.glsl
@@ -10,10 +10,10 @@ uniform vec3 lightPos;
 
 void main()
 {
+  // calculate distance in world coordinates
   float lightDist = length(lightPos - FragPos);
   float c1 = lightDist;
   float c2 = lightDist;
   float c3 = lightDist;
   FragColor = vec4(c1, c2, c3, 1);
-  //FragColor = vec4(LocalPos/10, 1);
 }
diff --git a/shaders/vert_irradiance.glsl b/shaders/vert_irradiance.glsl
index 6b54180..89ba12e 100644
--- a/shaders/vert_irradiance.glsl
+++ b/shaders/vert_irradiance.glsl
@@ -23,55 +23,37 @@ uniform mat4 lightViewInv;
 uniform mat4 projection;
 uniform mat4 lightProjection;
 
-vec4 blur(sampler2D tex, vec2 uv, vec2 res) {
-  float Pi = 6.28318530718; // Pi*2
-    
-  // GAUSSIAN BLUR SETTINGS {{{
-  float Directions = 16.0; // BLUR DIRECTIONS (Default 16.0 - More is better but slower)
-  float Quality = 4.0; // BLUR QUALITY (Default 4.0 - More is better but slower)
-  float Size = 8.0; // BLUR SIZE (Radius)
-  // GAUSSIAN BLUR SETTINGS }}}
-  
-  vec2 Radius = Size/res;
-  
-  // Pixel colour
-  vec4 Color = texture(tex, uv);
-  
-  // Blur calculations
-  for( float d=0.0; d<Pi; d+=Pi/Directions) {
-    for(float i=1.0/Quality; i<=1.0; i+=1.0/Quality) {
-      Color += texture( tex, uv+vec2(cos(d),sin(d))*Radius*i);		
-    }
-  }
-  
-  // Output to screen
-  Color /= Quality * Directions - 15.0;
-  return Color;
-}
-
 void main()
 {
   gl_Position = projection * view * model * vec4(pos, 1.0);
+  // calculate fragment position in world coordinates
   FragPos = vec3(model * vec4(pos, 1));
+  // and local coordinates
   LocalPos = pos;
+
   Normal = normal;
   
+  // get fragment position in the light's projection space
   vec4 lightSpace = lightProjection * lightView * model * vec4(pos, 1.0);
+  // and transform them to 2D coordinates
+  // (this is usually done by OpenGL after applying the vertex shader,
+  // so to get them here, we have to divide by w manually)
   lightSpace = lightSpace / lightSpace.w;
   vec2 shadowmapCoords = lightSpace.xy;
+  // map coordinates from [0 1] to [-1 +1]
+  // multiply by 0.99 first to shift coordinates towards the center slightly
+  // to prevent artifacts at the edges
   shadowmapCoords = vec2(
     (shadowmapCoords.x * 0.99 + 1) / 2,
     (shadowmapCoords.y * 0.99 + 1) / 2
   );
 
-
-  // blur
+  // sample shadowmap (brightness encodes distance of fragment to light)
   vec4 t = texture(shadowmapTexture, shadowmapCoords);
-  //vec4 t = blur(shadowmapTexture, shadowmapCoords, vec2(screenWidth, screenHeight));
 
-  BacksideIrradiance = t.r; //*100 + t.g + t.b/100;
+  BacksideIrradiance = t.r;
   
+  // calculate backside with distance(BacksideIrradiance) and lightDir
   vec3 lightDir = normalize(FragPos - lightPos);
   Backside = (lightPos + (lightDir * BacksideIrradiance));
-  //Backside = texture(shadowmapTexture, shadowmapCoords).xyz*10;
 }
diff --git a/shaders/vert_shadowmap.glsl b/shaders/vert_shadowmap.glsl
index 50847bb..a6c9398 100644
--- a/shaders/vert_shadowmap.glsl
+++ b/shaders/vert_shadowmap.glsl
@@ -14,6 +14,7 @@ uniform mat4 projection;
 void main()
 {
   gl_Position = projection * lightView * model * vec4(pos, 1.0);
+  // pass fragment position in world coordinates
   FragPos = vec3(model * vec4(pos, 1));
   LocalPos = pos;
   Normal = normal;
-- 
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