Merge pull request #58512 from Calinou/light3d-add-distance-fade

8 files changed, 99 insertions, 4 deletions

diff --git a/servers/rendering/rasterizer_dummy.h b/servers/rendering/rasterizer_dummy.h
index 74c080660d..987f2f4342 100644
--- a/servers/rendering/rasterizer_dummy.h
+++ b/servers/rendering/rasterizer_dummy.h
@@ -412,6 +412,7 @@ public:
 	void light_set_projector(RID p_light, RID p_texture) override {}
 	void light_set_negative(RID p_light, bool p_enable) override {}
 	void light_set_cull_mask(RID p_light, uint32_t p_mask) override {}
+	void light_set_distance_fade(RID p_light, bool p_enabled, float p_begin, float p_shadow, float p_length) override {}
 	void light_set_reverse_cull_face_mode(RID p_light, bool p_enabled) override {}
 	void light_set_bake_mode(RID p_light, RS::LightBakeMode p_bake_mode) override {}
 	void light_set_max_sdfgi_cascade(RID p_light, uint32_t p_cascade) override {}
diff --git a/servers/rendering/renderer_rd/renderer_scene_render_rd.cpp b/servers/rendering/renderer_rd/renderer_scene_render_rd.cpp
index db8f5461cf..8814822cda 100644
--- a/servers/rendering/renderer_rd/renderer_scene_render_rd.cpp
+++ b/servers/rendering/renderer_rd/renderer_scene_render_rd.cpp
@@ -3440,8 +3440,22 @@ void RendererSceneRenderRD::_setup_lights(const PagedArray<RID> &p_lights, const
 					continue;
 				}
 
+				const real_t distance = camera_plane.distance_to(li->transform.origin);
+
+				if (storage->light_is_distance_fade_enabled(li->light)) {
+					const float fade_begin = storage->light_get_distance_fade_begin(li->light);
+					const float fade_length = storage->light_get_distance_fade_length(li->light);
+
+					if (distance > fade_begin) {
+						if (distance > fade_begin + fade_length) {
+							// Out of range, don't draw this light to improve performance.
+							continue;
+						}
+					}
+				}
+
 				cluster.omni_light_sort[cluster.omni_light_count].instance = li;
-				cluster.omni_light_sort[cluster.omni_light_count].depth = camera_plane.distance_to(li->transform.origin);
+				cluster.omni_light_sort[cluster.omni_light_count].depth = distance;
 				cluster.omni_light_count++;
 			} break;
 			case RS::LIGHT_SPOT: {
@@ -3449,8 +3463,22 @@ void RendererSceneRenderRD::_setup_lights(const PagedArray<RID> &p_lights, const
 					continue;
 				}
 
+				const real_t distance = camera_plane.distance_to(li->transform.origin);
+
+				if (storage->light_is_distance_fade_enabled(li->light)) {
+					const float fade_begin = storage->light_get_distance_fade_begin(li->light);
+					const float fade_length = storage->light_get_distance_fade_length(li->light);
+
+					if (distance > fade_begin) {
+						if (distance > fade_begin + fade_length) {
+							// Out of range, don't draw this light to improve performance.
+							continue;
+						}
+					}
+				}
+
 				cluster.spot_light_sort[cluster.spot_light_count].instance = li;
-				cluster.spot_light_sort[cluster.spot_light_count].depth = camera_plane.distance_to(li->transform.origin);
+				cluster.spot_light_sort[cluster.spot_light_count].depth = distance;
 				cluster.spot_light_count++;
 			} break;
 		}
@@ -3494,7 +3522,24 @@ void RendererSceneRenderRD::_setup_lights(const PagedArray<RID> &p_lights, const
 
 		light_data.attenuation = storage->light_get_param(base, RS::LIGHT_PARAM_ATTENUATION);
 
-		float energy = sign * storage->light_get_param(base, RS::LIGHT_PARAM_ENERGY) * Math_PI;
+		// Reuse fade begin, fade length and distance for shadow LOD determination later.
+		float fade_begin = 0.0;
+		float fade_length = 0.0;
+		real_t distance = 0.0;
+
+		float fade = 1.0;
+		if (storage->light_is_distance_fade_enabled(li->light)) {
+			fade_begin = storage->light_get_distance_fade_begin(li->light);
+			fade_length = storage->light_get_distance_fade_length(li->light);
+			distance = camera_plane.distance_to(li->transform.origin);
+
+			if (distance > fade_begin) {
+				// Use `smoothstep()` to make opacity changes more gradual and less noticeable to the player.
+				fade = Math::smoothstep(0.0f, 1.0f, 1.0f - float(distance - fade_begin) / fade_length);
+			}
+		}
+
+		float energy = sign * storage->light_get_param(base, RS::LIGHT_PARAM_ENERGY) * Math_PI * fade;
 
 		light_data.color[0] = linear_col.r * energy;
 		light_data.color[1] = linear_col.g * energy;
@@ -3555,7 +3600,17 @@ void RendererSceneRenderRD::_setup_lights(const PagedArray<RID> &p_lights, const
 			light_data.projector_rect[3] = 0;
 		}
 
-		if (shadow_atlas && shadow_atlas->shadow_owners.has(li->self)) {
+		const bool needs_shadow = shadow_atlas && shadow_atlas->shadow_owners.has(li->self);
+
+		bool in_shadow_range = true;
+		if (needs_shadow && storage->light_is_distance_fade_enabled(li->light)) {
+			if (distance > storage->light_get_distance_fade_shadow(li->light)) {
+				// Out of range, don't draw shadows to improve performance.
+				in_shadow_range = false;
+			}
+		}
+
+		if (needs_shadow && in_shadow_range) {
 			// fill in the shadow information
 
 			light_data.shadow_enabled = true;
diff --git a/servers/rendering/renderer_rd/renderer_storage_rd.cpp b/servers/rendering/renderer_rd/renderer_storage_rd.cpp
index 1473a92a1a..35aa0f1f31 100644
--- a/servers/rendering/renderer_rd/renderer_storage_rd.cpp
+++ b/servers/rendering/renderer_rd/renderer_storage_rd.cpp
@@ -6600,6 +6600,16 @@ void RendererStorageRD::light_set_cull_mask(RID p_light, uint32_t p_mask) {
 	light->dependency.changed_notify(DEPENDENCY_CHANGED_LIGHT);
 }
 
+void RendererStorageRD::light_set_distance_fade(RID p_light, bool p_enabled, float p_begin, float p_shadow, float p_length) {
+	Light *light = light_owner.get_or_null(p_light);
+	ERR_FAIL_COND(!light);
+
+	light->distance_fade = p_enabled;
+	light->distance_fade_begin = p_begin;
+	light->distance_fade_shadow = p_shadow;
+	light->distance_fade_length = p_length;
+}
+
 void RendererStorageRD::light_set_reverse_cull_face_mode(RID p_light, bool p_enabled) {
 	Light *light = light_owner.get_or_null(p_light);
 	ERR_FAIL_COND(!light);
diff --git a/servers/rendering/renderer_rd/renderer_storage_rd.h b/servers/rendering/renderer_rd/renderer_storage_rd.h
index 33a3b8e229..cb35c2bf65 100644
--- a/servers/rendering/renderer_rd/renderer_storage_rd.h
+++ b/servers/rendering/renderer_rd/renderer_storage_rd.h
@@ -1033,6 +1033,10 @@ private:
 		RS::LightBakeMode bake_mode = RS::LIGHT_BAKE_DYNAMIC;
 		uint32_t max_sdfgi_cascade = 2;
 		uint32_t cull_mask = 0xFFFFFFFF;
+		bool distance_fade = false;
+		real_t distance_fade_begin = 40.0;
+		real_t distance_fade_shadow = 50.0;
+		real_t distance_fade_length = 10.0;
 		RS::LightOmniShadowMode omni_shadow_mode = RS::LIGHT_OMNI_SHADOW_DUAL_PARABOLOID;
 		RS::LightDirectionalShadowMode directional_shadow_mode = RS::LIGHT_DIRECTIONAL_SHADOW_ORTHOGONAL;
 		bool directional_blend_splits = false;
@@ -1841,6 +1845,7 @@ public:
 	void light_set_projector(RID p_light, RID p_texture);
 	void light_set_negative(RID p_light, bool p_enable);
 	void light_set_cull_mask(RID p_light, uint32_t p_mask);
+	void light_set_distance_fade(RID p_light, bool p_enabled, float p_begin, float p_shadow, float p_length);
 	void light_set_reverse_cull_face_mode(RID p_light, bool p_enabled);
 	void light_set_bake_mode(RID p_light, RS::LightBakeMode p_bake_mode);
 	void light_set_max_sdfgi_cascade(RID p_light, uint32_t p_cascade);
@@ -1899,6 +1904,26 @@ public:
 		return light->cull_mask;
 	}
 
+	_FORCE_INLINE_ bool light_is_distance_fade_enabled(RID p_light) {
+		const Light *light = light_owner.get_or_null(p_light);
+		return light->distance_fade;
+	}
+
+	_FORCE_INLINE_ float light_get_distance_fade_begin(RID p_light) {
+		const Light *light = light_owner.get_or_null(p_light);
+		return light->distance_fade_begin;
+	}
+
+	_FORCE_INLINE_ float light_get_distance_fade_shadow(RID p_light) {
+		const Light *light = light_owner.get_or_null(p_light);
+		return light->distance_fade_shadow;
+	}
+
+	_FORCE_INLINE_ float light_get_distance_fade_length(RID p_light) {
+		const Light *light = light_owner.get_or_null(p_light);
+		return light->distance_fade_length;
+	}
+
 	_FORCE_INLINE_ bool light_has_shadow(RID p_light) const {
 		const Light *light = light_owner.get_or_null(p_light);
 		ERR_FAIL_COND_V(!light, RS::LIGHT_DIRECTIONAL);
diff --git a/servers/rendering/renderer_storage.h b/servers/rendering/renderer_storage.h
index a2df7ad38e..762362afed 100644
--- a/servers/rendering/renderer_storage.h
+++ b/servers/rendering/renderer_storage.h
@@ -321,6 +321,7 @@ public:
 	virtual void light_set_projector(RID p_light, RID p_texture) = 0;
 	virtual void light_set_negative(RID p_light, bool p_enable) = 0;
 	virtual void light_set_cull_mask(RID p_light, uint32_t p_mask) = 0;
+	virtual void light_set_distance_fade(RID p_light, bool p_enabled, float p_begin, float p_shadow, float p_length) = 0;
 	virtual void light_set_reverse_cull_face_mode(RID p_light, bool p_enabled) = 0;
 	virtual void light_set_bake_mode(RID p_light, RS::LightBakeMode p_bake_mode) = 0;
 	virtual void light_set_max_sdfgi_cascade(RID p_light, uint32_t p_cascade) = 0;
diff --git a/servers/rendering/rendering_server_default.h b/servers/rendering/rendering_server_default.h
index 6d2c36537b..9ed2b2ad4f 100644
--- a/servers/rendering/rendering_server_default.h
+++ b/servers/rendering/rendering_server_default.h
@@ -346,6 +346,7 @@ public:
 	FUNC2(light_set_projector, RID, RID)
 	FUNC2(light_set_negative, RID, bool)
 	FUNC2(light_set_cull_mask, RID, uint32_t)
+	FUNC5(light_set_distance_fade, RID, bool, float, float, float)
 	FUNC2(light_set_reverse_cull_face_mode, RID, bool)
 	FUNC2(light_set_bake_mode, RID, LightBakeMode)
 	FUNC2(light_set_max_sdfgi_cascade, RID, uint32_t)
diff --git a/servers/rendering_server.cpp b/servers/rendering_server.cpp
index fe5c7dc0de..39a0acb2bd 100644
--- a/servers/rendering_server.cpp
+++ b/servers/rendering_server.cpp
@@ -1883,6 +1883,7 @@ void RenderingServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("light_set_projector", "light", "texture"), &RenderingServer::light_set_projector);
 	ClassDB::bind_method(D_METHOD("light_set_negative", "light", "enable"), &RenderingServer::light_set_negative);
 	ClassDB::bind_method(D_METHOD("light_set_cull_mask", "light", "mask"), &RenderingServer::light_set_cull_mask);
+	ClassDB::bind_method(D_METHOD("light_set_distance_fade", "decal", "enabled", "begin", "shadow", "length"), &RenderingServer::light_set_distance_fade);
 	ClassDB::bind_method(D_METHOD("light_set_reverse_cull_face_mode", "light", "enabled"), &RenderingServer::light_set_reverse_cull_face_mode);
 	ClassDB::bind_method(D_METHOD("light_set_bake_mode", "light", "bake_mode"), &RenderingServer::light_set_bake_mode);
 	ClassDB::bind_method(D_METHOD("light_set_max_sdfgi_cascade", "light", "cascade"), &RenderingServer::light_set_max_sdfgi_cascade);
diff --git a/servers/rendering_server.h b/servers/rendering_server.h
index 5748d8808b..533c000166 100644
--- a/servers/rendering_server.h
+++ b/servers/rendering_server.h
@@ -443,6 +443,7 @@ public:
 	virtual void light_set_projector(RID p_light, RID p_texture) = 0;
 	virtual void light_set_negative(RID p_light, bool p_enable) = 0;
 	virtual void light_set_cull_mask(RID p_light, uint32_t p_mask) = 0;
+	virtual void light_set_distance_fade(RID p_light, bool p_enabled, float p_begin, float p_shadow, float p_length) = 0;
 	virtual void light_set_reverse_cull_face_mode(RID p_light, bool p_enabled) = 0;
 
 	enum LightBakeMode {