Add Environment properties to control fog rendering on background sky

Values lower than 1.0 can be used to make the fog rendering not fully
obstruct the sky. This can be desired when using fog as a purely
atmospheric effect, without intending to use fog for open world fog
fading.

When set to 0.0, fog rendering behavior will be similar to Godot 3.x
where sky rendering was never affected by fog.

2 files changed, 22 insertions, 4 deletions

diff --git a/servers/rendering/storage/environment_storage.cpp b/servers/rendering/storage/environment_storage.cpp
index 1d4dc55e98..49b08f83aa 100644
--- a/servers/rendering/storage/environment_storage.cpp
+++ b/servers/rendering/storage/environment_storage.cpp
@@ -244,7 +244,7 @@ uint64_t RendererEnvironmentStorage::environment_get_auto_exposure_version(RID p
 
 // Fog
 
-void RendererEnvironmentStorage::environment_set_fog(RID p_env, bool p_enable, const Color &p_light_color, float p_light_energy, float p_sun_scatter, float p_density, float p_height, float p_height_density, float p_fog_aerial_perspective) {
+void RendererEnvironmentStorage::environment_set_fog(RID p_env, bool p_enable, const Color &p_light_color, float p_light_energy, float p_sun_scatter, float p_density, float p_height, float p_height_density, float p_fog_aerial_perspective, float p_sky_affect) {
 	Environment *env = environment_owner.get_or_null(p_env);
 	ERR_FAIL_COND(!env);
 	env->fog_enabled = p_enable;
@@ -255,6 +255,7 @@ void RendererEnvironmentStorage::environment_set_fog(RID p_env, bool p_enable, c
 	env->fog_height = p_height;
 	env->fog_height_density = p_height_density;
 	env->fog_aerial_perspective = p_fog_aerial_perspective;
+	env->fog_sky_affect = p_sky_affect;
 }
 
 bool RendererEnvironmentStorage::environment_get_fog_enabled(RID p_env) const {
@@ -305,9 +306,15 @@ float RendererEnvironmentStorage::environment_get_fog_aerial_perspective(RID p_e
 	return env->fog_aerial_perspective;
 }
 
+float RendererEnvironmentStorage::environment_get_fog_sky_affect(RID p_env) const {
+	Environment *env = environment_owner.get_or_null(p_env);
+	ERR_FAIL_COND_V(!env, 0.0);
+	return env->fog_sky_affect;
+}
+
 // Volumetric Fog
 
-void RendererEnvironmentStorage::environment_set_volumetric_fog(RID p_env, bool p_enable, float p_density, const Color &p_albedo, const Color &p_emission, float p_emission_energy, float p_anisotropy, float p_length, float p_detail_spread, float p_gi_inject, bool p_temporal_reprojection, float p_temporal_reprojection_amount, float p_ambient_inject) {
+void RendererEnvironmentStorage::environment_set_volumetric_fog(RID p_env, bool p_enable, float p_density, const Color &p_albedo, const Color &p_emission, float p_emission_energy, float p_anisotropy, float p_length, float p_detail_spread, float p_gi_inject, bool p_temporal_reprojection, float p_temporal_reprojection_amount, float p_ambient_inject, float p_sky_affect) {
 	Environment *env = environment_owner.get_or_null(p_env);
 	ERR_FAIL_COND(!env);
 	env->volumetric_fog_enabled = p_enable;
@@ -322,6 +329,7 @@ void RendererEnvironmentStorage::environment_set_volumetric_fog(RID p_env, bool
 	env->volumetric_fog_temporal_reprojection = p_temporal_reprojection;
 	env->volumetric_fog_temporal_reprojection_amount = p_temporal_reprojection_amount;
 	env->volumetric_fog_ambient_inject = p_ambient_inject;
+	env->volumetric_fog_sky_affect = p_sky_affect;
 }
 
 bool RendererEnvironmentStorage::environment_get_volumetric_fog_enabled(RID p_env) const {
@@ -378,6 +386,12 @@ float RendererEnvironmentStorage::environment_get_volumetric_fog_gi_inject(RID p
 	return env->volumetric_fog_gi_inject;
 }
 
+float RendererEnvironmentStorage::environment_get_volumetric_fog_sky_affect(RID p_env) const {
+	Environment *env = environment_owner.get_or_null(p_env);
+	ERR_FAIL_COND_V(!env, 0.0);
+	return env->volumetric_fog_sky_affect;
+}
+
 bool RendererEnvironmentStorage::environment_get_volumetric_fog_temporal_reprojection(RID p_env) const {
 	Environment *env = environment_owner.get_or_null(p_env);
 	ERR_FAIL_COND_V(!env, true);
diff --git a/servers/rendering/storage/environment_storage.h b/servers/rendering/storage/environment_storage.h
index 29bba86930..0e0f9d0541 100644
--- a/servers/rendering/storage/environment_storage.h
+++ b/servers/rendering/storage/environment_storage.h
@@ -71,6 +71,7 @@ private:
 		float fog_light_energy = 1.0;
 		float fog_sun_scatter = 0.0;
 		float fog_density = 0.01;
+		float fog_sky_affect = 1.0;
 		float fog_height = 0.0;
 		float fog_height_density = 0.0; //can be negative to invert effect
 		float fog_aerial_perspective = 0.0;
@@ -86,6 +87,7 @@ private:
 		float volumetric_fog_detail_spread = 2.0;
 		float volumetric_fog_gi_inject = 1.0;
 		float volumetric_fog_ambient_inject = 0.0;
+		float volumetric_fog_sky_affect = 1.0;
 		bool volumetric_fog_temporal_reprojection = true;
 		float volumetric_fog_temporal_reprojection_amount = 0.9;
 
@@ -202,18 +204,19 @@ public:
 	uint64_t environment_get_auto_exposure_version(RID p_env) const;
 
 	// Fog
-	void environment_set_fog(RID p_env, bool p_enable, const Color &p_light_color, float p_light_energy, float p_sun_scatter, float p_density, float p_height, float p_height_density, float p_aerial_perspective);
+	void environment_set_fog(RID p_env, bool p_enable, const Color &p_light_color, float p_light_energy, float p_sun_scatter, float p_density, float p_height, float p_height_density, float p_aerial_perspective, float p_sky_affect);
 	bool environment_get_fog_enabled(RID p_env) const;
 	Color environment_get_fog_light_color(RID p_env) const;
 	float environment_get_fog_light_energy(RID p_env) const;
 	float environment_get_fog_sun_scatter(RID p_env) const;
 	float environment_get_fog_density(RID p_env) const;
+	float environment_get_fog_sky_affect(RID p_env) const;
 	float environment_get_fog_height(RID p_env) const;
 	float environment_get_fog_height_density(RID p_env) const;
 	float environment_get_fog_aerial_perspective(RID p_env) const;
 
 	// Volumetric Fog
-	void environment_set_volumetric_fog(RID p_env, bool p_enable, float p_density, const Color &p_albedo, const Color &p_emission, float p_emission_energy, float p_anisotropy, float p_length, float p_detail_spread, float p_gi_inject, bool p_temporal_reprojection, float p_temporal_reprojection_amount, float p_ambient_inject);
+	void environment_set_volumetric_fog(RID p_env, bool p_enable, float p_density, const Color &p_albedo, const Color &p_emission, float p_emission_energy, float p_anisotropy, float p_length, float p_detail_spread, float p_gi_inject, bool p_temporal_reprojection, float p_temporal_reprojection_amount, float p_ambient_inject, float p_sky_affect);
 	bool environment_get_volumetric_fog_enabled(RID p_env) const;
 	float environment_get_volumetric_fog_density(RID p_env) const;
 	Color environment_get_volumetric_fog_scattering(RID p_env) const;
@@ -223,6 +226,7 @@ public:
 	float environment_get_volumetric_fog_length(RID p_env) const;
 	float environment_get_volumetric_fog_detail_spread(RID p_env) const;
 	float environment_get_volumetric_fog_gi_inject(RID p_env) const;
+	float environment_get_volumetric_fog_sky_affect(RID p_env) const;
 	bool environment_get_volumetric_fog_temporal_reprojection(RID p_env) const;
 	float environment_get_volumetric_fog_temporal_reprojection_amount(RID p_env) const;
 	float environment_get_volumetric_fog_ambient_inject(RID p_env) const;