Eevee: Bloom: Add Clamp setting

It's purpose is to limit the amount of light that spread across the screen.

Not entierly sure if it's very usefull, but it sure help to avoid to drown the screen in bloom.

release/scripts/startup/bl_ui/properties_render.py

@@ -680,6 +680,7 @@ class RENDER_PT_eevee_postprocess_settings(RenderButtonsPanel, Panel):
         col.prop(props, "bloom_knee")
         col.prop(props, "bloom_radius")
         col.prop(props, "bloom_intensity")
+        col.prop(props, "bloom_clamp")
 
 
 class RENDER_PT_eevee_volumetric(RenderButtonsPanel, Panel):

release/scripts/startup/bl_ui/properties_render_layer.py

@@ -215,6 +215,7 @@ class RENDERLAYER_PT_eevee_postprocess_settings(RenderLayerButtonsPanel, Panel):
         col.template_override_property(layer_props, scene_props, "bloom_knee")
         col.template_override_property(layer_props, scene_props, "bloom_radius")
         col.template_override_property(layer_props, scene_props, "bloom_intensity")
+        col.template_override_property(layer_props, scene_props, "bloom_clamp")
 
 
 class RENDERLAYER_PT_eevee_volumetric(RenderLayerButtonsPanel, Panel):

source/blender/draw/engines/eevee/eevee_effects.c

@@ -367,6 +367,7 @@ void EEVEE_effects_init(EEVEE_SceneLayerData *sldata, EEVEE_Data *vedata)
 		float knee = BKE_collection_engine_property_value_get_float(props, "bloom_knee");
 		float intensity = BKE_collection_engine_property_value_get_float(props, "bloom_intensity");
 		float radius = BKE_collection_engine_property_value_get_float(props, "bloom_radius");
+		effects->bloom_clamp = BKE_collection_engine_property_value_get_float(props, "bloom_clamp");
 
 		/* determine the iteration count */
 		const float minDim = (float)MIN2(blitsize[0], blitsize[1]);
@@ -1047,6 +1048,7 @@ void EEVEE_effects_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_Data *vedata)
 		eevee_create_bloom_pass("Bloom Upsample", effects, e_data.bloom_upsample_sh[use_highres], &psl->bloom_upsample, true);
 		grp = eevee_create_bloom_pass("Bloom Blit", effects, e_data.bloom_blit_sh[use_antiflicker], &psl->bloom_blit, false);
 		DRW_shgroup_uniform_vec4(grp, "curveThreshold", effects->bloom_curve_threshold, 1);
+		DRW_shgroup_uniform_float(grp, "clampIntensity", &effects->bloom_clamp, 1);
 		grp = eevee_create_bloom_pass("Bloom Resolve", effects, e_data.bloom_resolve_sh[use_highres], &psl->bloom_resolve, true);
 		DRW_shgroup_uniform_float(grp, "bloomIntensity", &effects->bloom_intensity, 1);
 	}

source/blender/draw/engines/eevee/eevee_engine.c

@@ -302,6 +302,7 @@ static void EEVEE_scene_layer_settings_create(RenderEngine *UNUSED(engine), IDPr
 	BKE_collection_engine_property_add_float(props, "bloom_knee", 0.5f);
 	BKE_collection_engine_property_add_float(props, "bloom_intensity", 0.8f);
 	BKE_collection_engine_property_add_float(props, "bloom_radius", 6.5f);
+	BKE_collection_engine_property_add_float(props, "bloom_clamp", 1.0f);
 
 	BKE_collection_engine_property_add_bool(props, "motion_blur_enable", false);
 	BKE_collection_engine_property_add_int(props, "motion_blur_samples", 8);

source/blender/draw/engines/eevee/eevee_private.h

@@ -370,6 +370,7 @@ typedef struct EEVEE_EffectsInfo {
 	float blit_texel_size[2];
 	float downsamp_texel_size[MAX_BLOOM_STEP][2];
 	float bloom_intensity;
+	float bloom_clamp;
 	float bloom_sample_scale;
 	float bloom_curve_threshold[4];
 	float unf_source_texel_size[2];

source/blender/draw/engines/eevee/shaders/effect_bloom_frag.glsl

@@ -31,6 +31,7 @@ uniform vec2 sourceBufferTexelSize;
 
 /* Step Blit */
 uniform vec4 curveThreshold;
+uniform float clampIntensity;
 
 /* Step Upsample */
 uniform sampler2D baseBuffer; /* Previous accumulation buffer */
@@ -161,7 +162,11 @@ vec4 step_blit(void)
 	rq = curveThreshold.z * rq * rq;
 
 	/* Combine and apply the brightness response curve. */
-	m *= max(rq, br - curveThreshold.w) / max(br, 1e-5);
+	m *= max(rq, br - curveThreshold.w) / max(1e-5, br);
+
+	/* Clamp pixel intensity */
+	br = max(1e-5, brightness(m));
+	m *= 1.0 - max(0.0, br - clampIntensity) / br;
 
 	return vec4(m, 1.0);
 }

source/blender/makesrna/intern/rna_scene.c

@@ -6477,6 +6477,15 @@ 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, "bloom_clamp", PROP_FLOAT, PROP_FACTOR);
+	RNA_def_property_float_funcs(prop, "rna_LayerEngineSettings_Eevee_bloom_clamp_get",
+	                             "rna_LayerEngineSettings_Eevee_bloom_clamp_set", NULL);
+	RNA_def_property_ui_text(prop, "Clamp", "Maximum intensity a bloom pixel can have");
+	RNA_def_property_range(prop, 0.0f, 1000.0f);
+	RNA_def_property_ui_range(prop, 0.0f, 10.0f, 1, 3);
+	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, "bloom_intensity", PROP_FLOAT, PROP_UNSIGNED);
 	RNA_def_property_float_funcs(prop, "rna_LayerEngineSettings_Eevee_bloom_intensity_get",
 	                             "rna_LayerEngineSettings_Eevee_bloom_intensity_set", NULL);