EEVEE-Next: Add exposure awareness to denoising

This uses the exposure to get a better approximation of the perceptual
brighness of a sample before accumulating it.

Note that we do not modify exposure of the image. Only the samples weights
are computed differently.

3 files changed, 8 insertions, 10 deletions

diff --git a/source/blender/draw/engines/eevee_next/eevee_film.cc b/source/blender/draw/engines/eevee_next/eevee_film.cc
index 486413a0834..42c61ac90a8 100644
--- a/source/blender/draw/engines/eevee_next/eevee_film.cc
+++ b/source/blender/draw/engines/eevee_next/eevee_film.cc
@@ -164,6 +164,8 @@ inline bool operator!=(const FilmData &a, const FilmData &b)
 void Film::init(const int2 &extent, const rcti *output_rect)
 {
   Sampling &sampling = inst_.sampling;
+  Scene &scene = *inst_.scene;
+  SceneEEVEE &scene_eevee = scene.eevee;
 
   init_aovs();
 
@@ -230,9 +232,8 @@ void Film::init(const int2 &extent, const rcti *output_rect)
     data.offset = int2(output_rect->xmin, output_rect->ymin);
     data.extent_inv = 1.0f / float2(data.extent);
     /* Disable filtering if sample count is 1. */
-    data.filter_size = (sampling.sample_count() == 1) ?
-                           0.0f :
-                           clamp_f(inst_.scene->r.gauss, 0.0f, 100.0f);
+    data.filter_size = (sampling.sample_count() == 1) ? 0.0f :
+                                                        clamp_f(scene.r.gauss, 0.0f, 100.0f);
     /* TODO(fclem): parameter hidden in experimental.
      * We need to figure out LOD bias first in order to preserve texture crispiness. */
     data.scaling_factor = 1;
@@ -254,7 +255,7 @@ void Film::init(const int2 &extent, const rcti *output_rect)
                                                    EEVEE_RENDER_PASS_MIST |
                                                    EEVEE_RENDER_PASS_SHADOW | EEVEE_RENDER_PASS_AO;
 
-    data_.exposure = 1.0f /* TODO */;
+    data_.exposure_scale = pow2f(scene.view_settings.exposure);
     data_.has_data = (enabled_passes_ & data_passes) != 0;
     data_.any_render_pass_1 = (enabled_passes_ & color_passes_1) != 0;
     data_.any_render_pass_2 = (enabled_passes_ & color_passes_2) != 0;
@@ -346,7 +347,7 @@ void Film::init(const int2 &extent, const rcti *output_rect)
     }
   }
 
-  force_disable_reprojection_ = (inst_.scene->eevee.flag & SCE_EEVEE_TAA_REPROJECTION) == 0;
+  force_disable_reprojection_ = (scene_eevee.flag & SCE_EEVEE_TAA_REPROJECTION) == 0;
 }
 
 void Film::sync()
diff --git a/source/blender/draw/engines/eevee_next/eevee_shader_shared.hh b/source/blender/draw/engines/eevee_next/eevee_shader_shared.hh
index 9cf7f75b2c3..819f49756d7 100644
--- a/source/blender/draw/engines/eevee_next/eevee_shader_shared.hh
+++ b/source/blender/draw/engines/eevee_next/eevee_shader_shared.hh
@@ -202,7 +202,7 @@ struct FilmData {
   /** Settings to render mist pass */
   float mist_scale, mist_bias, mist_exponent;
   /** Scene exposure used for better noise reduction. */
-  float exposure;
+  float exposure_scale;
   /** Scaling factor for scaled resolution rendering. */
   int scaling_factor;
   /** Film pixel filter radius. */
diff --git a/source/blender/draw/engines/eevee_next/shaders/eevee_film_lib.glsl b/source/blender/draw/engines/eevee_next/shaders/eevee_film_lib.glsl
index 451b8e8fca7..efd3d2dfe35 100644
--- a/source/blender/draw/engines/eevee_next/shaders/eevee_film_lib.glsl
+++ b/source/blender/draw/engines/eevee_next/shaders/eevee_film_lib.glsl
@@ -48,8 +48,6 @@ vec3 film_scene_linear_from_YCoCg(vec3 ycocg_color)
 vec4 film_texelfetch_as_YCoCg_opacity(sampler2D tx, ivec2 texel)
 {
   vec4 color = texelFetch(combined_tx, texel, 0);
-  /* Can we assume safe color from earlier pass? */
-  // color = safe_color(color);
   /* Convert transmittance to opacity. */
   color.a = saturate(1.0 - color.a);
   /* Transform to YCoCg for accumulation. */
@@ -62,8 +60,7 @@ float film_luma_weight(float luma)
 {
   /* Slide 20 of "High Quality Temporal Supersampling" by Brian Karis at Siggraph 2014. */
   /* To preserve more details in dark areas, we use a bigger bias. */
-  /* TODO(fclem): exposure weighting. */
-  return 1.0 / (4.0 + luma);
+  return 1.0 / (4.0 + luma * film_buf.exposure_scale);
 }
 
 /* -------------------------------------------------------------------- */