1 files changed, 90 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/eevee_volume_eval_lib.glsl b/source/blender/draw/engines/eevee/shaders/eevee_volume_eval_lib.glsl
new file mode 100644
index 00000000000..272b43047e9
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/eevee_volume_eval_lib.glsl
@@ -0,0 +1,90 @@
+
+#pragma BLENDER_REQUIRE(eevee_nodetree_eval_lib.glsl)
+#pragma BLENDER_REQUIRE(eevee_sampling_lib.glsl)
+
+struct Ray {
+  vec3 origin;
+  vec3 direction;
+  float max_time;
+};
+
+vec3 volume_eval_light(vec3 P, float anisotropy)
+{
+  vec3 light_out = vec3(0.0);
+  // LIGHT_ITER(g_volume)
+  // {
+  //   LightData ld = lights_data[i];
+
+  //   if (ld.l_volume == 0.0) {
+  //     continue;
+  //   }
+
+  //   vec3 L;
+  //   float dist;
+  //   light_vector_get(light, P, L, dist);
+
+  //   float visibility = light_attenuation(light, L, dist);
+
+  //   if (light.shadow_id != LIGHT_NO_SHADOW && visibility > 0.0) {
+  //     vec3 lL = light_world_to_local(light, -L) * dist;
+  //     vec3 shadow_co = shadow_punctual_coordinates_get(shadows[l_idx], lL);
+  //     visibility *= texture(shadow_atlas_tx, shadow_co);
+  //   }
+
+  //   if (visibility > 1e-4) {
+  //     float intensity = light_volume(utility_tx, light, V, L, dist, anisotropy);
+  //     light_out += light.color * (intensity * visibility);
+  //   }
+  // }
+  return light_out;
+}
+
+void volume_eval(vec3 P, vec3 V, float max_time, out vec3 out_radiance, out vec3 out_transmittance)
+{
+  // out_radiance = vec3(0);
+  // out_transmittance = vec3(1);
+
+  // VOLUME_ITER(g_volume)
+  // {
+  //   nodetree_eval();
+
+  //   vec3 scattered_light = g_volume_data.emission +
+  //                          g_volume_data.scattering * volume_eval_light(P,
+  //                          g_volume_data.anisotropy);
+
+  //   /* Emission does not work if there is no extinction because
+  //    * Tr evaluates to 1.0 leading to Lscat = 0.0. (See T65771) */
+  //   /* s_extinction. */
+  //   g_volume_data.transmittance = max(vec3(1e-7) * step(1e-5, Lscat),
+  //   g_volume_data.transmittance);
+  //   /* Evaluate Scattering. */
+  //   float s_len = abs(ray_len - prev_ray_len);
+  //   prev_ray_len = ray_len;
+  //   vec3 Tr = exp(-g_volume_data.transmittance * s_len);
+  //   /* Integrate along the current step segment. */
+  //   scattered_light = (scattered_light - scattered_light * Tr) *
+  //                     safe_rcp(g_volume_data.transmittance);
+  //   /* Accumulate and also take into account the transmittance from previous steps. */
+  //   out_radiance += out_transmittance * scattered_light;
+  //   out_transmittance *= Tr;
+
+  //   if (all(lessThan(out_transmittance, vec3(1e-4)))) {
+  //     break;
+  //   }
+  // }
+}
+
+/* Simple version that compute transmittance only. */
+void volume_eval_homogenous(Ray ray, inout vec3 out_transmittance, out vec3 out_depth_time)
+{
+  // nodetree_eval();
+
+  float step_len = length(ray.direction);
+
+  out_transmittance *= exp(-g_volume_data.transmittance * step_len * ray.max_time);
+
+  float threshold = interlieved_gradient_noise(gl_FragCoord.xy, 0, 0.0);
+  /* Find depth at which we have threshold opacity. */
+  out_depth_time = log(max(threshold, 1e-6)) * safe_rcp(-g_volume_data.transmittance * step_len);
+  out_depth_time = min(out_depth_time, vec3(ray.max_time));
+}