Add sky cover texture for ProceduralSkyMaterial

This brings PhysicalSkyMaterial's Night Sky functionality to
ProceduralSkyMaterial, but in a more powerful and general fashion.

This can be used to display stars at night, or clouds at day and night.
For clouds, it won't be physically accurate, but it can look good still.

The Sky Cover Modulate property can be used to adjust the sky cover's
colors and opacity in real-time, which is useful for day/night or weather
transitions.

2 files changed, 41 insertions, 0 deletions

diff --git a/scene/resources/sky_material.cpp b/scene/resources/sky_material.cpp
index 8e633a4075..54543782f6 100644
--- a/scene/resources/sky_material.cpp
+++ b/scene/resources/sky_material.cpp
@@ -71,6 +71,25 @@ float ProceduralSkyMaterial::get_sky_energy() const {
 	return sky_energy;
 }
 
+void ProceduralSkyMaterial::set_sky_cover(const Ref<Texture2D> &p_sky_cover) {
+	sky_cover = p_sky_cover;
+	RID tex_rid = p_sky_cover.is_valid() ? p_sky_cover->get_rid() : RID();
+	RS::get_singleton()->material_set_param(_get_material(), "sky_cover", tex_rid);
+}
+
+Ref<Texture2D> ProceduralSkyMaterial::get_sky_cover() const {
+	return sky_cover;
+}
+
+void ProceduralSkyMaterial::set_sky_cover_modulate(const Color &p_sky_cover_modulate) {
+	sky_cover_modulate = p_sky_cover_modulate;
+	RS::get_singleton()->material_set_param(_get_material(), "sky_cover_modulate", sky_cover_modulate);
+}
+
+Color ProceduralSkyMaterial::get_sky_cover_modulate() const {
+	return sky_cover_modulate;
+}
+
 void ProceduralSkyMaterial::set_ground_bottom_color(const Color &p_ground_bottom) {
 	ground_bottom_color = p_ground_bottom;
 	RS::get_singleton()->material_set_param(_get_material(), "ground_bottom_color", ground_bottom_color);
@@ -156,6 +175,12 @@ void ProceduralSkyMaterial::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_sky_energy", "energy"), &ProceduralSkyMaterial::set_sky_energy);
 	ClassDB::bind_method(D_METHOD("get_sky_energy"), &ProceduralSkyMaterial::get_sky_energy);
 
+	ClassDB::bind_method(D_METHOD("set_sky_cover", "sky_cover"), &ProceduralSkyMaterial::set_sky_cover);
+	ClassDB::bind_method(D_METHOD("get_sky_cover"), &ProceduralSkyMaterial::get_sky_cover);
+
+	ClassDB::bind_method(D_METHOD("set_sky_cover_modulate", "color"), &ProceduralSkyMaterial::set_sky_cover_modulate);
+	ClassDB::bind_method(D_METHOD("get_sky_cover_modulate"), &ProceduralSkyMaterial::get_sky_cover_modulate);
+
 	ClassDB::bind_method(D_METHOD("set_ground_bottom_color", "color"), &ProceduralSkyMaterial::set_ground_bottom_color);
 	ClassDB::bind_method(D_METHOD("get_ground_bottom_color"), &ProceduralSkyMaterial::get_ground_bottom_color);
 
@@ -179,6 +204,8 @@ void ProceduralSkyMaterial::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::COLOR, "sky_horizon_color", PROPERTY_HINT_COLOR_NO_ALPHA), "set_sky_horizon_color", "get_sky_horizon_color");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "sky_curve", PROPERTY_HINT_EXP_EASING), "set_sky_curve", "get_sky_curve");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "sky_energy", PROPERTY_HINT_RANGE, "0,64,0.01"), "set_sky_energy", "get_sky_energy");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "sky_cover", PROPERTY_HINT_RESOURCE_TYPE, "Texture2D"), "set_sky_cover", "get_sky_cover");
+	ADD_PROPERTY(PropertyInfo(Variant::COLOR, "sky_cover_modulate"), "set_sky_cover_modulate", "get_sky_cover_modulate");
 
 	ADD_GROUP("Ground", "ground_");
 	ADD_PROPERTY(PropertyInfo(Variant::COLOR, "ground_bottom_color", PROPERTY_HINT_COLOR_NO_ALPHA), "set_ground_bottom_color", "get_ground_bottom_color");
@@ -212,6 +239,8 @@ uniform vec4 sky_top_color : hint_color = vec4(0.385, 0.454, 0.55, 1.0);
 uniform vec4 sky_horizon_color : hint_color = vec4(0.646, 0.656, 0.67, 1.0);
 uniform float sky_curve : hint_range(0, 1) = 0.15;
 uniform float sky_energy = 1.0;
+uniform sampler2D sky_cover : hint_black_albedo;
+uniform vec4 sky_cover_modulate : hint_color = vec4(1.0, 1.0, 1.0, 1.0);
 uniform vec4 ground_bottom_color : hint_color = vec4(0.2, 0.169, 0.133, 1.0);
 uniform vec4 ground_horizon_color : hint_color = vec4(0.646, 0.656, 0.67, 1.0);
 uniform float ground_curve : hint_range(0, 1) = 0.02;
@@ -265,6 +294,9 @@ void sky() {
 		}
 	}
 
+	vec4 sky_cover_texture = texture(sky_cover, SKY_COORDS);
+	sky += (sky_cover_texture.rgb * sky_cover_modulate.rgb) * sky_cover_texture.a * sky_cover_modulate.a * sky_energy;
+
 	c = (v_angle - (PI * 0.5)) / (PI * 0.5);
 	vec3 ground = mix(ground_horizon_color.rgb, ground_bottom_color.rgb, clamp(1.0 - pow(1.0 - c, 1.0 / ground_curve), 0.0, 1.0));
 	ground *= ground_energy;
@@ -281,6 +313,7 @@ ProceduralSkyMaterial::ProceduralSkyMaterial() {
 	set_sky_horizon_color(Color(0.6463, 0.6558, 0.6708));
 	set_sky_curve(0.15);
 	set_sky_energy(1.0);
+	set_sky_cover_modulate(Color(1, 1, 1));
 
 	set_ground_bottom_color(Color(0.2, 0.169, 0.133));
 	set_ground_horizon_color(Color(0.6463, 0.6558, 0.6708));
diff --git a/scene/resources/sky_material.h b/scene/resources/sky_material.h
index 7f421beb8d..5c791a185a 100644
--- a/scene/resources/sky_material.h
+++ b/scene/resources/sky_material.h
@@ -42,6 +42,8 @@ private:
 	Color sky_horizon_color;
 	float sky_curve;
 	float sky_energy;
+	Ref<Texture2D> sky_cover;
+	Color sky_cover_modulate;
 
 	Color ground_bottom_color;
 	Color ground_horizon_color;
@@ -72,6 +74,12 @@ public:
 	void set_sky_energy(float p_energy);
 	float get_sky_energy() const;
 
+	void set_sky_cover(const Ref<Texture2D> &p_sky_cover);
+	Ref<Texture2D> get_sky_cover() const;
+
+	void set_sky_cover_modulate(const Color &p_sky_cover_modulate);
+	Color get_sky_cover_modulate() const;
+
 	void set_ground_bottom_color(const Color &p_ground_bottom);
 	Color get_ground_bottom_color() const;