Extract cooefs

This PR wraps the reflection probes data used by shaders in a new
struct. Soon this new struct will get new attributes to store
the spherical harmonics of the environment.

@@ -38,6 +38,7 @@ struct ReflectionProbe {
   bool do_update_data = false;
   /* Should the area in the probes_tx_ be updated? */
   bool do_render = false;
+  bool do_update_irradiance = false;

@@ -167,6 +170,7 @@ class ReflectionProbeModule {
   std::optional<ReflectionProbeUpdateInfo> update_info_pop(ReflectionProbe::Type probe_type);
   void remap_to_octahedral_projection(uint64_t object_key);
   void update_probes_texture_mipmaps();
+  void update_irradiance(uint64_t object_key);

@@ -0,0 +1,84 @@
+
+/* Shader to extract spherical harmonics cooefs from octahedral mapped reflection probe. */
+/* TODO(jbakker): Use larger dispatch size and atomic add. */

@@ -0,0 +37,4 @@
+
+  barrier();
+
+  /* Determine the LOD to sample. We locate mipmap level that contains the 64x64 subdivision what

@@ -0,0 +54,4 @@
+    vec2 rand = fract(hammersley_2d(sample_index + sample_offset, total_samples));
+    vec3 direction = sample_sphere(rand);
+    vec4 light = reflection_probes_sample(direction, layer_mipmap, probe_data);
+    spherical_harmonics_encode_signal_sample(

@@ -105,0 +107,4 @@
+  float omega = rand.y * 2.0 * M_PI;
+  float cos_theta = rand.x * 2.0 - 1.0;
+  float sin_theta = safe_sqrt(1.0 - cos_theta * cos_theta);
+  return vec3(sin_theta * vec2(cosf(omega), sinf(omega)), cos_theta);