Eevee: Volumetrics: Add Light contribution clamping.

This avoid too much variance at light centers and remove some noise.

6 files changed, 27 insertions, 9 deletions

diff --git a/release/scripts/startup/bl_ui/properties_render.py b/release/scripts/startup/bl_ui/properties_render.py
index 40307a1d3bb..5dc90850841 100644
--- a/release/scripts/startup/bl_ui/properties_render.py
+++ b/release/scripts/startup/bl_ui/properties_render.py
@@ -704,6 +704,7 @@ class RENDER_PT_eevee_volumetric(RenderButtonsPanel, Panel):
         col.prop(props, "volumetric_samples")
         col.prop(props, "volumetric_sample_distribution")
         col.prop(props, "volumetric_lights")
+        col.prop(props, "volumetric_light_clamp")
         col.prop(props, "volumetric_shadows")
         col.prop(props, "volumetric_shadow_samples")
         col.prop(props, "volumetric_colored_transmittance")
diff --git a/source/blender/draw/engines/eevee/eevee_effects.c b/source/blender/draw/engines/eevee/eevee_effects.c
index 602d4f272b8..86997d44e0f 100644
--- a/source/blender/draw/engines/eevee/eevee_effects.c
+++ b/source/blender/draw/engines/eevee/eevee_effects.c
@@ -434,6 +434,12 @@ void EEVEE_effects_init(EEVEE_SceneLayerData *sldata, EEVEE_Data *vedata)
 			volumetrics->sample_distribution = BKE_collection_engine_property_value_get_float(props, "volumetric_sample_distribution");
 			volumetrics->integration_step_count = (float)BKE_collection_engine_property_value_get_int(props, "volumetric_samples");
 			volumetrics->shadow_step_count = (float)BKE_collection_engine_property_value_get_int(props, "volumetric_shadow_samples");
+			volumetrics->light_clamp = BKE_collection_engine_property_value_get_float(props, "volumetric_light_clamp");
+
+			/* Disable clamp if equal to 0. */
+			if (volumetrics->light_clamp == 0.0) {
+				volumetrics->light_clamp = FLT_MAX;
+			}
 
 			volumetrics->use_lights = BKE_collection_engine_property_value_get_bool(props, "volumetric_lights");
 			volumetrics->use_volume_shadows = BKE_collection_engine_property_value_get_bool(props, "volumetric_shadows");
@@ -522,7 +528,7 @@ void EEVEE_effects_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_Data *vedata)
 			DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
 			DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)stl->g_data->viewvecs, 2);
 			DRW_shgroup_uniform_vec2(grp, "volume_start_end", &sldata->volumetrics->integration_start, 1);
-			DRW_shgroup_uniform_vec3(grp, "volume_samples", &sldata->volumetrics->integration_step_count, 1);
+			DRW_shgroup_uniform_vec4(grp, "volume_samples_clamp", &sldata->volumetrics->integration_step_count, 1);
 			DRW_shgroup_call_add(grp, quad, NULL);
 
 			if (volumetrics->use_colored_transmit == false) { /* Monochromatic transmittance */
diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index feee13b06f8..3c65e1e1763 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -196,6 +196,7 @@ static void EEVEE_scene_layer_settings_create(RenderEngine *UNUSED(engine), IDPr
 	BKE_collection_engine_property_add_int(props, "volumetric_samples", 64);
 	BKE_collection_engine_property_add_float(props, "volumetric_sample_distribution", 0.8);
 	BKE_collection_engine_property_add_bool(props, "volumetric_lights", true);
+	BKE_collection_engine_property_add_float(props, "volumetric_light_clamp", 0.0f);
 	BKE_collection_engine_property_add_bool(props, "volumetric_shadows", false);
 	BKE_collection_engine_property_add_int(props, "volumetric_shadow_samples", 16);
 	BKE_collection_engine_property_add_bool(props, "volumetric_colored_transmittance", true);
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index 286d833fca3..6175b656521 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -188,7 +188,7 @@ typedef struct EEVEE_ShadowRender {
 
 /* ************ VOLUME DATA ************ */
 typedef struct EEVEE_VolumetricsInfo {
-	float integration_step_count, shadow_step_count, sample_distribution;
+	float integration_step_count, shadow_step_count, sample_distribution, light_clamp;
 	float integration_start, integration_end;
 	bool use_lights, use_volume_shadows, use_colored_transmit;
 } EEVEE_VolumetricsInfo;
diff --git a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
index 916ff01b520..56fa126e490 100644
--- a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
@@ -6,14 +6,15 @@
 
 uniform int light_count;
 uniform vec2 volume_start_end;
-uniform vec3 volume_samples;
+uniform vec4 volume_samples_clamp;
 
 #define volume_start                   volume_start_end.x
 #define volume_end                     volume_start_end.y
 
-#define volume_integration_steps       volume_samples.x
-#define volume_shadows_steps           volume_samples.y
-#define volume_sample_distribution     volume_samples.z
+#define volume_integration_steps       volume_samples_clamp.x
+#define volume_shadows_steps           volume_samples_clamp.y
+#define volume_sample_distribution     volume_samples_clamp.z
+#define volume_light_clamp             volume_samples_clamp.w
 
 #ifdef COLOR_TRANSMITTANCE
 layout(location = 0) out vec4 outScattering;
@@ -74,7 +75,7 @@ float phase_function(vec3 v, vec3 l, float g)
 #endif
 }
 
-vec3 light_volume(LightData ld, vec4 l_vector)
+float light_volume(LightData ld, vec4 l_vector)
 {
 	float power;
 	float dist = max(1e-4, abs(l_vector.w - ld.l_radius));
@@ -87,7 +88,7 @@ vec3 light_volume(LightData ld, vec4 l_vector)
 	else {
 		power = 0.0248 * (4.0 * ld.l_radius * ld.l_radius * M_PI * M_PI);
 	}
-	return ld.l_color * power / (l_vector.w * l_vector.w);
+	return min(power / (l_vector.w * l_vector.w), volume_light_clamp);
 }
 
 vec3 irradiance_volumetric(vec3 wpos)
@@ -205,7 +206,7 @@ void main()
 
 			float Vis = light_visibility(ld, ray_wpos, l_vector);
 
-			vec3 Li = light_volume(ld, l_vector) * light_volume_shadow(ld, ray_wpos, l_vector, s_extinction);
+			vec3 Li = ld.l_color * light_volume(ld, l_vector) * light_volume_shadow(ld, ray_wpos, l_vector, s_extinction);
 
 			Lscat += Li * Vis * s_scattering * phase_function(-wdir, l_vector.xyz / l_vector.w, s_anisotropy);
 		}
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index 09a075cb128..c20a54fba69 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -2618,6 +2618,7 @@ RNA_LAYER_ENGINE_EEVEE_GET_SET_FLOAT(volumetric_end)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_INT(volumetric_samples)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_FLOAT(volumetric_sample_distribution)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_BOOL(volumetric_lights)
+RNA_LAYER_ENGINE_EEVEE_GET_SET_FLOAT(volumetric_light_clamp)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_BOOL(volumetric_shadows)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_INT(volumetric_shadow_samples)
 RNA_LAYER_ENGINE_EEVEE_GET_SET_BOOL(volumetric_colored_transmittance)
@@ -6223,6 +6224,14 @@ static void rna_def_scene_layer_engine_settings_eevee(BlenderRNA *brna)
 	RNA_def_property_flag(prop, PROP_CONTEXT_UPDATE);
 	RNA_def_property_update(prop, NC_SCENE | ND_LAYER_CONTENT, "rna_SceneLayerEngineSettings_update");
 
+	prop = RNA_def_property(srna, "volumetric_light_clamp", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_float_funcs(prop, "rna_LayerEngineSettings_Eevee_volumetric_light_clamp_get",
+	                               "rna_LayerEngineSettings_Eevee_volumetric_light_clamp_set", NULL);
+	RNA_def_property_range(prop, 0.0f, FLT_MAX);
+	RNA_def_property_ui_text(prop, "Clamp", "Maximum light contribution, reducing noise");
+	RNA_def_property_flag(prop, PROP_CONTEXT_UPDATE);
+	RNA_def_property_update(prop, NC_SCENE | ND_LAYER_CONTENT, "rna_SceneLayerEngineSettings_update");
+
 	prop = RNA_def_property(srna, "volumetric_shadows", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_funcs(prop, "rna_LayerEngineSettings_Eevee_volumetric_shadows_get",
 	                               "rna_LayerEngineSettings_Eevee_volumetric_shadows_set");