docs(7): Add section descriptions

src/7_planet.fs

@@ -22,6 +22,175 @@ out vec3 color;
 // perlin_noise, tangent
 void main()
 {
-  color = vec3(0,0,1);
-}
+  const float sun_orbit = 10.0;
+  const float sun_height = 8.0;
+  const float sun_frequency = 8.0;
+  const float epsilon = 0.0001;
 
+  const float cloud_scale = 0.9;
+  const float cloud_intensity = 32.5;
+  const float cloud_speed = 0.5;
+
+  const float light_intensity = 5.0;
+  const float twinkle_speed = 0.2;
+
+  /* * * * * *
+   *   Sun   *
+   * * * * * */
+  float sun_x = sun_orbit * cos(2.0 * M_PI * animation_seconds / sun_frequency);
+  float sun_z = sun_orbit * sin(2.0 * M_PI * animation_seconds / sun_frequency);
+  vec3 sun_pos = (view * vec4(vec3(sun_x, sun_height, sun_z), 1.0)).xyz;
+
+  vec3 light_dir = normalize(sun_pos - view_pos_fs_in.xyz);
+  vec3 view_dir = normalize(-view_pos_fs_in.xyz);
+  vec3 normal_dir = normalize(normal_fs_in);
+
+  /* * * * * * *
+   *   Bumps   *
+   * * * * * * */
+  vec3 T, B;
+  tangent(normalize(sphere_fs_in), T, B);
+
+  vec3 normal = cross(
+    (bump_position(is_moon, sphere_fs_in + epsilon * T) - bump_position(is_moon, sphere_fs_in)) / epsilon,
+    (bump_position(is_moon, sphere_fs_in + epsilon * B) - bump_position(is_moon, sphere_fs_in)) / epsilon
+  );
+  normal = (view * model(is_moon, animation_seconds) * vec4(normal, 0.0)).xyz;
+  normal = normalize(normal);
+
+  /* * * * * * *
+   *   Color-pre   *
+   * * * * * * */
+  float sun_specular_exponent = 1000.0;
+  vec3 ka = vec3(0.1, 0.1, 0.1);
+  vec3 kd;
+  vec3 ks = vec3(1.0, 1.0, 1.0);
+
+  float bump = bump_height(is_moon, normalize(sphere_fs_in));
+
+  if (!is_moon) {
+    /* * * * * * *
+     *   Planet  *
+     * * * * * * */
+
+    /* Water */
+    if (bump < 0.0) {
+      kd = vec3(0.2, 0.35, 0.8);
+      sun_specular_exponent = 4000.0;
+
+      float terrain_color = clamp(1 + 15 * bump, 0, 1); /* Still show the depth in the color */
+      kd *= terrain_color;
+
+      // Create very small waves, by multiplying the normal with a perlin value
+      float wave = perlin_noise(sphere_fs_in * 30 + animation_seconds);
+      wave = pow(wave, 0.1);
+      wave = 0.1 * smoothstep(0.1, 0.9, wave);
+      wave = clamp(wave, 0.0, 1.0);
+
+      normal = normal_dir + normal*wave;
+      normal = normalize(normal);
+    }
+    /* Land */
+    else {
+      ks = vec3(0.0, 0.0, 0.0);
+      kd = vec3(0.2, 0.8, 0.3);
+
+      vec3 beach = vec3(0.9, 0.8, 0.5);
+      vec3 lush = vec3(0.2, 0.8, 0.3);
+      vec3 barren = vec3(0.5, 0.5, 0.5);
+
+      if (bump < 0.05) {
+        kd = mix(beach, lush, smoothstep(0.0, 0.05, bump));
+      } else {
+        kd = mix(lush, barren, smoothstep(0.05, 1.0, bump));
+      }
+
+      float terrain_color = clamp(1 + 15 * bump, 0, 1);
+      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);
+
+    float base_cloud = perlin_noise(sphere_fs_in.xyz * 1.3 + cloud_rotation / 5.0);
+    base_cloud = pow(base_cloud, 1.1);
+    base_cloud = 100.0 * smoothstep(0.1, 0.9, base_cloud);
+    base_cloud = clamp(base_cloud, 0.0, 1.0);
+
+    float top_cloud = perlin_noise(sphere_fs_in.xyz * 3.5 + cloud_rotation);
+    top_cloud = pow(top_cloud, 1.125);
+    top_cloud = 3.8 * smoothstep(0.1, 0.9, top_cloud);
+    top_cloud = clamp(top_cloud, 0.0, 1.0);
+
+    /* Combine the base and top cloud */
+    float cloud = top_cloud * base_cloud;
+
+    kd = mix(kd, vec3(1.0, 1.0, 1.0), cloud);
+    kd = clamp(kd, 0.0, 1.0);
+
+    // 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 */
+    float light_factor = dot(normal, light_dir);
+    if (light_factor < -0.2 && 0.0 < bump) { // Only show the twinkle when the light is coming from the front
+      vec3 twinkle_vector = vec3(animation_seconds * twinkle_speed, 0.0, animation_seconds * twinkle_speed);
+      float twinkle_pos = perlin_noise(sphere_fs_in * 100 + twinkle_vector);
+      twinkle_pos = pow(twinkle_pos, 1.35);
+      float twinkle_intensity = perlin_noise(sphere_fs_in * 0.5 * twinkle_vector);
+      twinkle_pos = twinkle_intensity * 100.0 * smoothstep(0.3, 1.0, twinkle_pos);
+      twinkle_pos = clamp(twinkle_pos, 0.0, 1.0);
+
+      // RGB LIGHTS! (Groetjes aan Julie)
+      float r_mix = perlin_noise(sphere_fs_in * twinkle_vector * animation_seconds + 1.0);
+      r_mix = 1000 * smoothstep(0.01, 0.95, r_mix);
+      r_mix = clamp(r_mix, 0.0, 1.0);
+      float g_mix = perlin_noise(sphere_fs_in * twinkle_vector * animation_seconds + 2.0);
+      g_mix = 1000 * smoothstep(0.01, 0.95, g_mix);
+      g_mix = clamp(g_mix, 0.0, 1.0);
+      float b_mix = perlin_noise(sphere_fs_in * twinkle_vector * animation_seconds + 3.0);
+      b_mix = 1000 * smoothstep(0.01, 0.95, b_mix);
+      b_mix = clamp(b_mix, 0.0, 1.0);
+
+      vec3 twinkle_color = vec3(r_mix, g_mix, b_mix);
+      vec3 final_twinkle_color = mix(vec3(1.0, 1.0, 1.0), twinkle_color, r_mix);
+
+      color = mix(color, final_twinkle_color, twinkle_pos);
+      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);
+    charcoal = clamp(charcoal, 0.0, 1.0);
+
+    kd = mix(kd, vec3(1.0, 0.0, 0.0), 1.0 - charcoal);
+
+    // 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);
+
+    /* 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);
+    glow_intensity = 1.1 * smoothstep(0.1, 0.9, glow_intensity);
+    glow_intensity = clamp(glow_intensity, 0.2, 1.0);
+    color *= glow_intensity;
+  }
+}