docs(7): Add section descriptions

src/7_planet.fs

@@ -59,7 +59,7 @@ void main()
   normal = normalize(normal);
 
   /* * * * * * *
-   *   Color   *
+   *   Color-pre   *
    * * * * * * */
   float sun_specular_exponent = 1000.0;
   vec3 ka = vec3(0.1, 0.1, 0.1);
@@ -69,7 +69,12 @@ void main()
   float bump = bump_height(is_moon, normalize(sphere_fs_in));
 
   if (!is_moon) {
-    if (bump < 0.0) { /* Water */
+    /* * * * * * *
+     *   Planet  *
+     * * * * * * */
+
+    /* Water */
+    if (bump < 0.0) {
       kd = vec3(0.2, 0.35, 0.8);
       sun_specular_exponent = 4000.0;
 
@@ -84,7 +89,9 @@ void main()
 
       normal = normal_dir + normal*wave;
       normal = normalize(normal);
-    } else { /* Land */
+    }
+    /* Land */
+    else {
       ks = vec3(0.0, 0.0, 0.0);
       kd = vec3(0.2, 0.8, 0.3);
 
@@ -102,6 +109,7 @@ void main()
       kd *= terrain_color;
     }
 
+    /* Clouds */
     // Generate clouds, by creating cloud clusters and then filling those clusters with clouds.
     vec3 cloud_rotation = vec3(animation_seconds * cloud_speed, 0.0, animation_seconds * cloud_speed);
 
@@ -124,6 +132,7 @@ void main()
     // Modify the normals to make the clouds look fluffy
     normal = mix(normal, normal_dir, cloud);
 
+    /* Color */
     color = blinn_phong(ka, kd, ks, sun_specular_exponent, normal, view_dir, light_dir);
 
     /* Twinking lights */
@@ -154,10 +163,15 @@ void main()
       color = clamp(color, 0.0, 1.0);
     }
   } else {
+    /* * * * * * *
+     *   Moon    *
+     * * * * * * */
+
     kd = vec3(0.2, 0.2, 0.2);
     sun_specular_exponent = 500.0;
     ks = vec3(0.1, 0.1, 0.1);
 
+    /* Charcoal color */
     float charcoal = perlin_noise(sphere_fs_in.xyz * 2.3);
     charcoal = pow(charcoal, 0.3);
     charcoal = 1.1 * smoothstep(0.1, 0.9, charcoal);
@@ -168,9 +182,10 @@ void main()
     // Smoothen the bumped normal
     normal = mix(normal, normal_dir, 1 - charcoal);
 
+    /* Color */
     color = blinn_phong(ka, kd, ks, sun_specular_exponent, normal, view_dir, light_dir);
 
-    /* Add charcoal glow */
+    /* Charcoal glow */
     color = mix(color, kd, 1.0 - charcoal);
     float glow_intensity = perlin_noise(vec3(0.25 * animation_seconds));
     glow_intensity = pow(glow_intensity, 0.3);