Implement Physical Light Units as an optional setting.

This allows light sources to be specified in physical light units in addition to the regular energy multiplier. In order to avoid loss of precision at high values, brightness values are premultiplied by an exposure normalization value.

In support of Physical Light Units this PR also renames CameraEffects to CameraAttributes.

2 files changed, 69 insertions, 24 deletions

diff --git a/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp b/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp
index 8754e90647..8421598275 100644
--- a/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp
+++ b/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp
@@ -906,8 +906,9 @@ void RenderForwardClustered::_setup_environment(const RenderDataRD *p_render_dat
 		RS::EnvironmentBG env_bg = environment_get_background(p_render_data->environment);
 		RS::EnvironmentAmbientSource ambient_src = environment_get_ambient_source(p_render_data->environment);
 
-		float bg_energy = environment_get_bg_energy(p_render_data->environment);
-		scene_state.ubo.ambient_light_color_energy[3] = bg_energy;
+		float bg_energy_multiplier = environment_get_bg_energy_multiplier(p_render_data->environment);
+
+		scene_state.ubo.ambient_light_color_energy[3] = bg_energy_multiplier;
 
 		scene_state.ubo.ambient_color_sky_mix = environment_get_ambient_sky_contribution(p_render_data->environment);
 
@@ -916,9 +917,9 @@ void RenderForwardClustered::_setup_environment(const RenderDataRD *p_render_dat
 			Color color = env_bg == RS::ENV_BG_CLEAR_COLOR ? p_default_bg_color : environment_get_bg_color(p_render_data->environment);
 			color = color.srgb_to_linear();
 
-			scene_state.ubo.ambient_light_color_energy[0] = color.r * bg_energy;
-			scene_state.ubo.ambient_light_color_energy[1] = color.g * bg_energy;
-			scene_state.ubo.ambient_light_color_energy[2] = color.b * bg_energy;
+			scene_state.ubo.ambient_light_color_energy[0] = color.r * bg_energy_multiplier;
+			scene_state.ubo.ambient_light_color_energy[1] = color.g * bg_energy_multiplier;
+			scene_state.ubo.ambient_light_color_energy[2] = color.b * bg_energy_multiplier;
 			scene_state.ubo.use_ambient_light = true;
 			scene_state.ubo.use_ambient_cubemap = false;
 		} else {
@@ -987,6 +988,25 @@ void RenderForwardClustered::_setup_environment(const RenderDataRD *p_render_dat
 		scene_state.ubo.ss_effects_flags = 0;
 	}
 
+	if (p_render_data->camera_attributes.is_valid()) {
+		scene_state.ubo.emissive_exposure_normalization = RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes);
+		scene_state.ubo.IBL_exposure_normalization = 1.0;
+		if (is_environment(p_render_data->environment)) {
+			RID sky_rid = environment_get_sky(p_render_data->environment);
+			if (sky_rid.is_valid()) {
+				float current_exposure = RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes) * environment_get_bg_intensity(p_render_data->environment) / _render_buffers_get_luminance_multiplier();
+				scene_state.ubo.IBL_exposure_normalization = current_exposure / MAX(0.001, sky.sky_get_baked_exposure(sky_rid));
+			}
+		}
+	} else if (scene_state.ubo.emissive_exposure_normalization > 0.0) {
+		// This branch is triggered when using render_material().
+		// Emissive is set outside the function, so don't set it.
+		// IBL isn't used don't set it.
+	} else {
+		scene_state.ubo.emissive_exposure_normalization = 1.0;
+		scene_state.ubo.IBL_exposure_normalization = 1.0;
+	}
+
 	scene_state.ubo.roughness_limiter_enabled = p_opaque_render_buffers && screen_space_roughness_limiter_is_active();
 	scene_state.ubo.roughness_limiter_amount = screen_space_roughness_limiter_get_amount();
 	scene_state.ubo.roughness_limiter_limit = screen_space_roughness_limiter_get_limit();
@@ -1383,7 +1403,7 @@ void RenderForwardClustered::_setup_voxelgis(const PagedArray<RID> &p_voxelgis)
 	}
 }
 
-void RenderForwardClustered::_setup_lightmaps(const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform) {
+void RenderForwardClustered::_setup_lightmaps(const RenderDataRD *p_render_data, const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform) {
 	scene_state.lightmaps_used = 0;
 	for (int i = 0; i < (int)p_lightmaps.size(); i++) {
 		if (i >= (int)scene_state.max_lightmaps) {
@@ -1395,6 +1415,13 @@ void RenderForwardClustered::_setup_lightmaps(const PagedArray<RID> &p_lightmaps
 		Basis to_lm = lightmap_instance_get_transform(p_lightmaps[i]).basis.inverse() * p_cam_transform.basis;
 		to_lm = to_lm.inverse().transposed(); //will transform normals
 		RendererRD::MaterialStorage::store_transform_3x3(to_lm, scene_state.lightmaps[i].normal_xform);
+		scene_state.lightmaps[i].exposure_normalization = 1.0;
+		if (p_render_data->camera_attributes.is_valid()) {
+			float baked_exposure = RendererRD::LightStorage::get_singleton()->lightmap_get_baked_exposure_normalization(lightmap);
+			float enf = RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes);
+			scene_state.lightmaps[i].exposure_normalization = enf / baked_exposure;
+		}
+
 		scene_state.lightmap_ids[i] = p_lightmaps[i];
 		scene_state.lightmap_has_sh[i] = RendererRD::LightStorage::get_singleton()->lightmap_uses_spherical_harmonics(lightmap);
 
@@ -1513,9 +1540,11 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 	scene_state.ubo.viewport_size[0] = screen_size.x;
 	scene_state.ubo.viewport_size[1] = screen_size.y;
 
+	scene_state.ubo.emissive_exposure_normalization = -1.0;
+
 	RD::get_singleton()->draw_command_begin_label("Render Setup");
 
-	_setup_lightmaps(*p_render_data->lightmaps, p_render_data->cam_transform);
+	_setup_lightmaps(p_render_data, *p_render_data->lightmaps, p_render_data->cam_transform);
 	_setup_voxelgis(*p_render_data->voxel_gi_instances);
 	_setup_environment(p_render_data, p_render_data->reflection_probe.is_valid(), screen_size, !p_render_data->reflection_probe.is_valid(), p_default_bg_color, false);
 
@@ -1539,6 +1568,8 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 	RID radiance_texture;
 	bool draw_sky = false;
 	bool draw_sky_fog_only = false;
+	// We invert luminance_multiplier for sky so that we can combine it with exposure value.
+	float sky_energy_multiplier = 1.0 / _render_buffers_get_luminance_multiplier();
 
 	Color clear_color;
 	bool keep_color = false;
@@ -1547,13 +1578,19 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 		clear_color = Color(0, 0, 0, 1); //in overdraw mode, BG should always be black
 	} else if (is_environment(p_render_data->environment)) {
 		RS::EnvironmentBG bg_mode = environment_get_background(p_render_data->environment);
-		float bg_energy = environment_get_bg_energy(p_render_data->environment);
+		float bg_energy_multiplier = environment_get_bg_energy_multiplier(p_render_data->environment);
+		bg_energy_multiplier *= environment_get_bg_intensity(p_render_data->environment);
+
+		if (p_render_data->camera_attributes.is_valid()) {
+			bg_energy_multiplier *= RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes);
+		}
+
 		switch (bg_mode) {
 			case RS::ENV_BG_CLEAR_COLOR: {
 				clear_color = p_default_bg_color;
-				clear_color.r *= bg_energy;
-				clear_color.g *= bg_energy;
-				clear_color.b *= bg_energy;
+				clear_color.r *= bg_energy_multiplier;
+				clear_color.g *= bg_energy_multiplier;
+				clear_color.b *= bg_energy_multiplier;
 				if ((p_render_data->render_buffers.is_valid() && render_buffers_has_volumetric_fog(p_render_data->render_buffers)) || environment_get_fog_enabled(p_render_data->environment)) {
 					draw_sky_fog_only = true;
 					RendererRD::MaterialStorage::get_singleton()->material_set_param(sky.sky_scene_state.fog_material, "clear_color", Variant(clear_color.srgb_to_linear()));
@@ -1561,9 +1598,9 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 			} break;
 			case RS::ENV_BG_COLOR: {
 				clear_color = environment_get_bg_color(p_render_data->environment);
-				clear_color.r *= bg_energy;
-				clear_color.g *= bg_energy;
-				clear_color.b *= bg_energy;
+				clear_color.r *= bg_energy_multiplier;
+				clear_color.g *= bg_energy_multiplier;
+				clear_color.b *= bg_energy_multiplier;
 				if ((p_render_data->render_buffers.is_valid() && render_buffers_has_volumetric_fog(p_render_data->render_buffers)) || environment_get_fog_enabled(p_render_data->environment)) {
 					draw_sky_fog_only = true;
 					RendererRD::MaterialStorage::get_singleton()->material_set_param(sky.sky_scene_state.fog_material, "clear_color", Variant(clear_color.srgb_to_linear()));
@@ -1594,11 +1631,13 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 				projection = correction * p_render_data->cam_projection;
 			}
 
-			sky.setup(p_render_data->environment, p_render_data->render_buffers, *p_render_data->lights, projection, p_render_data->cam_transform, screen_size, this);
+			sky.setup(p_render_data->environment, p_render_data->render_buffers, *p_render_data->lights, p_render_data->camera_attributes, projection, p_render_data->cam_transform, screen_size, this);
+
+			sky_energy_multiplier *= bg_energy_multiplier;
 
 			RID sky_rid = environment_get_sky(p_render_data->environment);
 			if (sky_rid.is_valid()) {
-				sky.update(p_render_data->environment, projection, p_render_data->cam_transform, time);
+				sky.update(p_render_data->environment, projection, p_render_data->cam_transform, time, sky_energy_multiplier);
 				radiance_texture = sky.sky_get_radiance_texture_rd(sky_rid);
 			} else {
 				// do not try to draw sky if invalid
@@ -1753,9 +1792,9 @@ void RenderForwardClustered::_render_scene(RenderDataRD *p_render_data, const Co
 			Projection correction;
 			correction.set_depth_correction(true);
 			Projection projection = correction * p_render_data->cam_projection;
-			sky.draw(p_render_data->environment, can_continue_color, can_continue_depth, color_only_framebuffer, 1, &projection, p_render_data->cam_transform, time);
+			sky.draw(p_render_data->environment, can_continue_color, can_continue_depth, color_only_framebuffer, 1, &projection, p_render_data->cam_transform, time, sky_energy_multiplier);
 		} else {
-			sky.draw(p_render_data->environment, can_continue_color, can_continue_depth, color_only_framebuffer, p_render_data->view_count, p_render_data->view_projection, p_render_data->cam_transform, time);
+			sky.draw(p_render_data->environment, can_continue_color, can_continue_depth, color_only_framebuffer, p_render_data->view_count, p_render_data->view_projection, p_render_data->cam_transform, time, sky_energy_multiplier);
 		}
 		RD::get_singleton()->draw_command_end_label();
 	}
@@ -2000,7 +2039,7 @@ void RenderForwardClustered::_render_particle_collider_heightfield(RID p_fb, con
 	RD::get_singleton()->draw_command_end_label();
 }
 
-void RenderForwardClustered::_render_material(const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal, const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region) {
+void RenderForwardClustered::_render_material(const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal, const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region, float p_exposure_normalization) {
 	RENDER_TIMESTAMP("Setup Rendering 3D Material");
 
 	RD::get_singleton()->draw_command_begin_label("Render 3D Material");
@@ -2018,6 +2057,7 @@ void RenderForwardClustered::_render_material(const Transform3D &p_cam_transform
 	scene_state.ubo.dual_paraboloid_side = 0;
 	scene_state.ubo.material_uv2_mode = false;
 	scene_state.ubo.opaque_prepass_threshold = 0.0f;
+	scene_state.ubo.emissive_exposure_normalization = p_exposure_normalization;
 
 	_setup_environment(&render_data, true, Vector2(1, 1), false, Color());
 
@@ -2064,6 +2104,7 @@ void RenderForwardClustered::_render_uv2(const PagedArray<RenderGeometryInstance
 	scene_state.ubo.dual_paraboloid_side = 0;
 	scene_state.ubo.material_uv2_mode = true;
 	scene_state.ubo.opaque_prepass_threshold = 0.0;
+	scene_state.ubo.emissive_exposure_normalization = -1.0;
 
 	_setup_environment(&render_data, true, Vector2(1, 1), false, Color());
 
@@ -2119,7 +2160,7 @@ void RenderForwardClustered::_render_uv2(const PagedArray<RenderGeometryInstance
 	RD::get_singleton()->draw_command_end_label();
 }
 
-void RenderForwardClustered::_render_sdfgi(RID p_render_buffers, const Vector3i &p_from, const Vector3i &p_size, const AABB &p_bounds, const PagedArray<RenderGeometryInstance *> &p_instances, const RID &p_albedo_texture, const RID &p_emission_texture, const RID &p_emission_aniso_texture, const RID &p_geom_facing_texture) {
+void RenderForwardClustered::_render_sdfgi(RID p_render_buffers, const Vector3i &p_from, const Vector3i &p_size, const AABB &p_bounds, const PagedArray<RenderGeometryInstance *> &p_instances, const RID &p_albedo_texture, const RID &p_emission_texture, const RID &p_emission_aniso_texture, const RID &p_geom_facing_texture, float p_exposure_normalization) {
 	RENDER_TIMESTAMP("Render SDFGI");
 
 	RD::get_singleton()->draw_command_begin_label("Render SDFGI Voxel");
@@ -2187,6 +2228,7 @@ void RenderForwardClustered::_render_sdfgi(RID p_render_buffers, const Vector3i
 
 		RendererRD::MaterialStorage::store_transform(to_bounds.affine_inverse() * render_data.cam_transform, scene_state.ubo.sdf_to_bounds);
 
+		scene_state.ubo.emissive_exposure_normalization = p_exposure_normalization;
 		_setup_environment(&render_data, true, Vector2(1, 1), false, Color());
 
 		RID rp_uniform_set = _setup_sdfgi_render_pass_uniform_set(p_albedo_texture, p_emission_texture, p_emission_aniso_texture, p_geom_facing_texture);
diff --git a/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.h b/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.h
index 7e71406af8..3d74f6769e 100644
--- a/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.h
+++ b/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.h
@@ -218,6 +218,8 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 
 	struct LightmapData {
 		float normal_xform[12];
+		float pad[3];
+		float exposure_normalization;
 	};
 
 	struct LightmapCaptureData {
@@ -324,7 +326,8 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 			uint32_t pancake_shadows;
 
 			float taa_jitter[2];
-			uint32_t pad[2];
+			float emissive_exposure_normalization; // Needed to normalize emissive when using physical units.
+			float IBL_exposure_normalization;
 		};
 
 		struct PushConstant {
@@ -397,7 +400,7 @@ class RenderForwardClustered : public RendererSceneRenderRD {
 
 	void _setup_environment(const RenderDataRD *p_render_data, bool p_no_fog, const Size2i &p_screen_size, bool p_flip_y, const Color &p_default_bg_color, bool p_opaque_render_buffers = false, bool p_pancake_shadows = false, int p_index = 0);
 	void _setup_voxelgis(const PagedArray<RID> &p_voxelgis);
-	void _setup_lightmaps(const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform);
+	void _setup_lightmaps(const RenderDataRD *p_render_data, const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform);
 
 	struct RenderElementInfo {
 		enum { MAX_REPEATS = (1 << 20) - 1 };
@@ -618,9 +621,9 @@ protected:
 	virtual void _render_shadow_process() override;
 	virtual void _render_shadow_end(uint32_t p_barrier = RD::BARRIER_MASK_ALL) override;
 
-	virtual void _render_material(const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal, const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region) override;
+	virtual void _render_material(const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal, const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region, float p_exposure_normalization) override;
 	virtual void _render_uv2(const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region) override;
-	virtual void _render_sdfgi(RID p_render_buffers, const Vector3i &p_from, const Vector3i &p_size, const AABB &p_bounds, const PagedArray<RenderGeometryInstance *> &p_instances, const RID &p_albedo_texture, const RID &p_emission_texture, const RID &p_emission_aniso_texture, const RID &p_geom_facing_texture) override;
+	virtual void _render_sdfgi(RID p_render_buffers, const Vector3i &p_from, const Vector3i &p_size, const AABB &p_bounds, const PagedArray<RenderGeometryInstance *> &p_instances, const RID &p_albedo_texture, const RID &p_emission_texture, const RID &p_emission_aniso_texture, const RID &p_geom_facing_texture, float p_exposure_normalization) override;
 	virtual void _render_particle_collider_heightfield(RID p_fb, const Transform3D &p_cam_transform, const Projection &p_cam_projection, const PagedArray<RenderGeometryInstance *> &p_instances) override;
 
 public: