Add High Quality Once update mode to Sky

doc/classes/RenderingServer.xml

@@ -4026,12 +4026,15 @@
 		</constant>
 		<constant name="SKY_MODE_AUTOMATIC" value="0" enum="SkyMode">
 		</constant>
-		<constant name="SKY_MODE_QUALITY" value="1" enum="SkyMode">
+		<constant name="SKY_MODE_QUALITY_ONCE" value="1" enum="SkyMode">
+			Uses high quality importance sampling to process the radiance map. In general, this results in much higher quality than [constant Sky.PROCESS_MODE_REALTIME] but takes much longer to generate. Run-time updates are disabled to improve performance (at the cost of the radiance map being incorrect if the sky changes too much). Swapping the sky resource for another one will force the radiance map to update (but changing its properties won't). If you are finding that the reflection is not blurry enough and is showing sparkles or fireflies, try increasing [member ProjectSettings.rendering/reflections/sky_reflections/ggx_samples].
+		</constant>
+		<constant name="SKY_MODE_QUALITY" value="2" enum="SkyMode">
 			Uses high quality importance sampling to process the radiance map. In general, this results in much higher quality than [constant Sky.PROCESS_MODE_REALTIME] but takes much longer to generate. This should not be used if you plan on changing the sky at runtime. If you are finding that the reflection is not blurry enough and is showing sparkles or fireflies, try increasing [member ProjectSettings.rendering/reflections/sky_reflections/ggx_samples].
 		</constant>
-		<constant name="SKY_MODE_INCREMENTAL" value="2" enum="SkyMode">
+		<constant name="SKY_MODE_INCREMENTAL" value="3" enum="SkyMode">
 		</constant>
-		<constant name="SKY_MODE_REALTIME" value="3" enum="SkyMode">
+		<constant name="SKY_MODE_REALTIME" value="4" enum="SkyMode">
 			Uses the fast filtering algorithm to process the radiance map. In general this results in lower quality, but substantially faster run times.
 			[b]Note:[/b] The fast filtering algorithm is limited to 256x256 cubemaps, so [member Sky.radiance_size] must be set to [constant Sky.RADIANCE_SIZE_256].
 		</constant>

scene/resources/sky.cpp

@@ -83,7 +83,7 @@ void Sky::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_material"), &Sky::get_material);
 
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "sky_material", PROPERTY_HINT_RESOURCE_TYPE, "ShaderMaterial,PanoramaSkyMaterial,ProceduralSkyMaterial,PhysicalSkyMaterial"), "set_material", "get_material");
-	ADD_PROPERTY(PropertyInfo(Variant::INT, "process_mode", PROPERTY_HINT_ENUM, "Automatic,HighQuality,HighQualityIncremental,RealTime"), "set_process_mode", "get_process_mode");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "process_mode", PROPERTY_HINT_ENUM, "Automatic,High Quality Once (Fastest),High Quality (Slow),High Quality Incremental (Average),Real-Time (Fast)"), "set_process_mode", "get_process_mode");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "radiance_size", PROPERTY_HINT_ENUM, "32,64,128,256,512,1024,2048"), "set_radiance_size", "get_radiance_size");
 
 	BIND_ENUM_CONSTANT(RADIANCE_SIZE_32);

servers/rendering/renderer_rd/renderer_scene_sky_rd.cpp

@@ -1228,7 +1228,8 @@ void RendererSceneSkyRD::update(RendererSceneEnvironmentRD *p_env, const CameraM
 
 	float multiplier = p_env->bg_energy;
 
-	bool update_single_frame = sky->mode == RS::SKY_MODE_REALTIME || sky->mode == RS::SKY_MODE_QUALITY;
+	bool should_update_sky = sky->reflection.dirty && sky->mode != RS::SKY_MODE_QUALITY_ONCE;
+	bool update_single_frame = sky->mode == RS::SKY_MODE_REALTIME || sky->mode == RS::SKY_MODE_QUALITY || sky->mode == RS::SKY_MODE_QUALITY_ONCE;
 	RS::SkyMode sky_mode = sky->mode;
 
 	if (sky_mode == RS::SKY_MODE_AUTOMATIC) {
@@ -1244,16 +1245,23 @@ void RendererSceneSkyRD::update(RendererSceneEnvironmentRD *p_env, const CameraM
 		}
 	}
 
-	if (sky->processing_layer == 0 && sky_mode == RS::SKY_MODE_INCREMENTAL) {
-		// On the first frame after creating sky, rebuild in single frame
-		update_single_frame = true;
-		sky_mode = RS::SKY_MODE_QUALITY;
+	if (sky->processing_layer == 0) {
+		if (sky_mode == RS::SKY_MODE_QUALITY_ONCE) {
+			// Only update the sky once after it was created.
+			should_update_sky = true;
+		}
+
+		if (sky_mode == RS::SKY_MODE_INCREMENTAL) {
+			// On the first frame after creating sky, rebuild in single frame
+			update_single_frame = true;
+			sky_mode = RS::SKY_MODE_QUALITY;
+		}
 	}
 
 	int max_processing_layer = sky_use_cubemap_array ? sky->reflection.layers.size() : sky->reflection.layers[0].mipmaps.size();
 
 	// Update radiance cubemap
-	if (sky->reflection.dirty && (sky->processing_layer >= max_processing_layer || update_single_frame)) {
+	if (should_update_sky && (sky->processing_layer >= max_processing_layer || update_single_frame)) {
 		static const Vector3 view_normals[6] = {
 			Vector3(+1, 0, 0),
 			Vector3(-1, 0, 0),

servers/rendering_server.cpp

@@ -2295,6 +2295,7 @@ void RenderingServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("sky_bake_panorama", "sky", "energy", "bake_irradiance", "size"), &RenderingServer::sky_bake_panorama);
 
 	BIND_ENUM_CONSTANT(SKY_MODE_AUTOMATIC);
+	BIND_ENUM_CONSTANT(SKY_MODE_QUALITY_ONCE);
 	BIND_ENUM_CONSTANT(SKY_MODE_QUALITY);
 	BIND_ENUM_CONSTANT(SKY_MODE_INCREMENTAL);
 	BIND_ENUM_CONSTANT(SKY_MODE_REALTIME);

servers/rendering_server.h

@@ -936,6 +936,7 @@ class RenderingServer : public Object {
 
 	enum SkyMode {
 		SKY_MODE_AUTOMATIC,
+		SKY_MODE_QUALITY_ONCE,
 		SKY_MODE_QUALITY,
 		SKY_MODE_INCREMENTAL,
 		SKY_MODE_REALTIME