source/blender/draw/engines/eevee_next/eevee_instance.cc

@@ -486,8 +486,10 @@ void Instance::light_bake_irradiance(
   });
 
   int bounce_len = scene->eevee.gi_diffuse_bounces;
-  /* Start at bounce 1 as 0 bounce is no indirect lighting. */
-  for (int bounce = 1; bounce <= bounce_len; bounce++) {
+  for (int bounce = 0; bounce <= bounce_len; bounce++) {
+    /* Last iteration only captures lighting. */
+    const bool is_last_bounce = (bounce == bounce_len);
+
     sampling.init(scene);
     while (!sampling.finished()) {
       context_wrapper([&]() {
@@ -495,9 +497,16 @@ void Instance::light_bake_irradiance(
          * the update function & context switch. */
         for (int i = 0; i < 16 && !sampling.finished(); i++) {
           sampling.step();
-          irradiance_cache.bake.propagate_light_sample();
+
+          irradiance_cache.bake.raylists_build();
+          if (!is_last_bounce) {
+            irradiance_cache.bake.propagate_light();
+          }
+          if (is_last_bounce) {
+            irradiance_cache.bake.irradiance_capture();
+          }
         }
-        if (sampling.finished()) {
+        if (sampling.finished() && !is_last_bounce) {
           irradiance_cache.bake.accumulate_bounce();
         }
 
@@ -511,7 +520,7 @@ void Instance::light_bake_irradiance(
         }
 
         float bounce_progress = sampling.sample_index() / float(sampling.sample_count());
-        float progress = (bounce - 1 + bounce_progress) / float(bounce_len);
+        float progress = (bounce + bounce_progress) / float(bounce_len + 1);
         result_update(cache_frame, progress);
       });
 

source/blender/draw/engines/eevee_next/eevee_irradiance_cache.cc

@@ -399,7 +399,7 @@ void IrradianceBake::sync()
     pass.dispatch(&dispatch_per_surfel_);
   }
   {
-    PassSimple &pass = surfel_light_propagate_ps_;
+    PassSimple &pass = surfel_ray_build_ps_;
     pass.init();
     {
       PassSimple::Sub &sub = pass.sub("ListBuild");
@@ -421,6 +421,10 @@ void IrradianceBake::sync()
       sub.barrier(GPU_BARRIER_SHADER_STORAGE);
       sub.dispatch(&dispatch_per_list_);
     }
+  }
+  {
+    PassSimple &pass = surfel_light_propagate_ps_;
+    pass.init();
     {
       PassSimple::Sub &sub = pass.sub("RayEval");
       sub.shader_set(inst_.shaders.static_shader_get(SURFEL_RAY));
@@ -500,10 +504,7 @@ void IrradianceBake::surfels_create(const Object &probe_object)
   capture_info_buf_.irradiance_grid_local_to_world = grid_local_to_world;
   capture_info_buf_.irradiance_grid_world_to_local_rotation = float4x4(
       (invert(normalize(float3x3(grid_local_to_world)))));
-  capture_info_buf_.irradiance_accum_solid_angle = 0.0f;
-  /* Divide by twice the sample count because each ray is evaluated in both directions. */
-  capture_info_buf_.irradiance_sample_solid_angle = 4.0f * float(M_PI) /
-                                                    (2 * inst_.sampling.sample_count());
+  capture_info_buf_.irradiance_accum_sample_count = 0;
 
   eGPUTextureUsage texture_usage = GPU_TEXTURE_USAGE_SHADER_READ | GPU_TEXTURE_USAGE_SHADER_WRITE |
                                    GPU_TEXTURE_USAGE_HOST_READ | GPU_TEXTURE_USAGE_ATTACHMENT;
@@ -633,6 +634,8 @@ void IrradianceBake::surfels_create(const Object &probe_object)
 
   /* Sync with any other following pass using the surfel buffer. */
   GPU_memory_barrier(GPU_BARRIER_SHADER_STORAGE);
+  /* Read back so that following push_update will contain correct surfel count. */
+  capture_info_buf_.read();
 
   DRW_stats_group_end();
 }
@@ -649,7 +652,7 @@ void IrradianceBake::surfels_lights_eval()
   inst_.manager->submit(surfel_light_eval_ps_, view_z_);
 }
 
-void IrradianceBake::propagate_light_sample()
+void IrradianceBake::raylists_build()
 {
   using namespace blender::math;
 
@@ -670,8 +673,7 @@ void IrradianceBake::propagate_light_sample()
   /* NOTE: Z values do not really matter since we are not doing any rasterization. */
   const float4x4 winmat = projection::orthographic<float>(min.x, max.x, min.y, max.y, 0, 1);
 
-  View ray_view = {"RayProjectionView"};
-  ray_view.sync(viewmat, winmat);
+  ray_view_.sync(viewmat, winmat);
 
   /* This avoid light leaking by making sure that for one surface there will always be at least 1
    * surfel capture inside a ray list. Since the surface with the maximum distance (after
@@ -694,8 +696,22 @@ void IrradianceBake::propagate_light_sample()
   list_start_buf_.resize(ceil_to_multiple_u(list_info_buf_.list_max, 4));
 
   GPU_storagebuf_clear(list_start_buf_, -1);
-  inst_.manager->submit(surfel_light_propagate_ps_, ray_view);
-  inst_.manager->submit(irradiance_capture_ps_, ray_view);
+  inst_.manager->submit(surfel_ray_build_ps_, ray_view_);
+}
+
+void IrradianceBake::propagate_light()
+{
+  inst_.manager->submit(surfel_light_propagate_ps_, ray_view_);
+}
+
+void IrradianceBake::irradiance_capture()
+{
+  capture_info_buf_.push_update();
+
+  inst_.manager->submit(irradiance_capture_ps_, ray_view_);
+
+  /* Increment twice because each ray is evaluated in both directions. */
+  capture_info_buf_.irradiance_accum_sample_count += 2;
 }
 
 void IrradianceBake::accumulate_bounce()

source/blender/draw/engines/eevee_next/eevee_irradiance_cache.hh

@@ -41,6 +41,8 @@ class IrradianceBake {
   Framebuffer empty_raster_fb_ = {"empty_raster_fb_"};
   /** Evaluate light object contribution and store result to surfel. */
   PassSimple surfel_light_eval_ps_ = {"LightEval"};
+  /** Create linked list of surfel to emulated raycast. */
+  PassSimple surfel_ray_build_ps_ = {"RayBuild"};
   /** Propagate light from surfel to surfel. */
   PassSimple surfel_light_propagate_ps_ = {"LightPropagate"};
   /** Start of a light bounce. Accumulate light from previous propagation. */
@@ -78,6 +80,9 @@ class IrradianceBake {
   /* Dispatch size for per grid sample workload. */
   int3 dispatch_per_grid_sample_ = int3(1);
 
+  /** View used to flatten the surfels into surfel lists representing rays. */
+  View ray_view_ = {"RayProjectionView"};
+
   /** Irradiance textures for baking. Only represents one grid in there. */
   Texture irradiance_L0_tx_ = {"irradiance_L0_tx_"};
   Texture irradiance_L1_a_tx_ = {"irradiance_L1_a_tx_"};
@@ -100,8 +105,12 @@ class IrradianceBake {
   void surfels_create(const Object &probe_object);
   /** Evaluate direct lighting (and also clear the surfels radiance). */
   void surfels_lights_eval();
+  /** Create a surfel lists to emulate ray-casts for the current sample random direction. */
+  void raylists_build();
   /** Propagate light from surfel to surfel in a random direction over the sphere. */
-  void propagate_light_sample();
+  void propagate_light();
+  /** Store surfel irradiance inside the irradiance grid samples. */
+  void irradiance_capture();
   /** Accumulate light inside `surfel.radiance_bounce` to `surfel.radiance`. */
   void accumulate_bounce();
 

source/blender/draw/engines/eevee_next/eevee_shader_shared.hh

@@ -870,10 +870,10 @@ struct CaptureInfoData {
   bool1 do_surfel_count;
   /** Number of surfels inside the surfel buffer or the needed len. */
   uint surfel_len;
-  /** Solid angle subtended by a single ray sample. Equal to `4 * pi / sample_count`. */
-  float irradiance_sample_solid_angle;
-  /** Accumulated solid angle. Should reach `4 * pi` at the end of the accumulation. */
-  float irradiance_accum_solid_angle;
+
+  float _pad3;
+  /** Accumulated directional samples in irradiance grid. */
+  int irradiance_accum_sample_count;
   /** Transform of the lightprobe object. */
   float4x4 irradiance_grid_local_to_world;
   /** Transform vectors from world space to local space. Does not have location component. */

source/blender/draw/engines/eevee_next/shaders/eevee_lightprobe_irradiance_ray_comp.glsl

@@ -18,15 +18,15 @@ void irradiance_capture(vec3 L, vec3 irradiance, inout SphericalHarmonicL1 sh)
 {
   vec3 lL = transform_direction(capture_info_buf.irradiance_grid_world_to_local_rotation, L);
 
-  spherical_harmonics_encode_signal_sample(
-      lL, vec4(irradiance, 1.0) * capture_info_buf.irradiance_sample_solid_angle, sh);
+  spherical_harmonics_encode_signal_sample(lL, vec4(irradiance, 1.0), sh);
 }
 
 void irradiance_capture(Surfel surfel_emitter, vec3 P, inout SphericalHarmonicL1 sh)
 {
   vec3 L = safe_normalize(surfel_emitter.position - P);
   bool facing = dot(-L, surfel_emitter.normal) > 0.0;
-  vec3 irradiance = facing ? surfel_emitter.radiance_front : surfel_emitter.radiance_back;
+  vec3 irradiance = facing ? surfel_emitter.outgoing_light_front :
+                             surfel_emitter.outgoing_light_back;
 
   irradiance_capture(L, irradiance, sh);
 }
@@ -67,6 +67,15 @@ void main()
   sh.L1.M0 = imageLoad(irradiance_L1_b_img, grid_coord);
   sh.L1.Mp1 = imageLoad(irradiance_L1_c_img, grid_coord);
 
+  /* Spherical harmonics need to be weighted by sphere area. */
+  const float sphere_area = 4.0 * M_PI;
+  /* Un-normalize for accumulation. */
+  float weight_captured = float(capture_info_buf.irradiance_accum_sample_count) / sphere_area;
+  sh.L0.M0 *= weight_captured;
+  sh.L1.Mn1 *= weight_captured;
+  sh.L1.M0 *= weight_captured;
+  sh.L1.Mp1 *= weight_captured;
+
   if (surfel_next > -1) {
     irradiance_capture(surfel_buf[surfel_next], P, sh);
   }
@@ -83,6 +92,13 @@ void main()
     irradiance_capture(-sky_L, vec3(0.0), sh);
   }
 
+  /* Normalize for storage. */
+  weight_captured += 2.0 / sphere_area;
+  sh.L0.M0 /= weight_captured;
+  sh.L1.Mn1 /= weight_captured;
+  sh.L1.M0 /= weight_captured;
+  sh.L1.Mp1 /= weight_captured;
+
   imageStore(irradiance_L0_img, grid_coord, sh.L0.M0);
   imageStore(irradiance_L1_a_img, grid_coord, sh.L1.Mn1);
   imageStore(irradiance_L1_b_img, grid_coord, sh.L1.M0);