Change the roughness limiter constants to perform better.

Use the roughness  amount and roughness constants from Filament.

Author: fire

doc/classes/ProjectSettings.xml

@@ -1555,7 +1555,7 @@
 		</member>
 		<member name="rendering/anti_aliasing/quality/use_debanding" type="bool" setter="" getter="" default="false">
 		</member>
-		<member name="rendering/anti_aliasing/screen_space_roughness_limiter/amount" type="float" setter="" getter="" default="0.25">
+		<member name="rendering/anti_aliasing/screen_space_roughness_limiter/amount" type="float" setter="" getter="" default="0.159155">
 		</member>
 		<member name="rendering/anti_aliasing/screen_space_roughness_limiter/enabled" type="bool" setter="" getter="" default="true">
 		</member>

servers/rendering/renderer_rd/renderer_scene_render_rd.h

@@ -589,7 +589,7 @@ class RendererSceneRenderRD : public RendererSceneRender {
 
 	/* GI */
 	bool screen_space_roughness_limiter = false;
-	float screen_space_roughness_limiter_amount = 0.25;
+	float screen_space_roughness_limiter_amount = 0.15915494;
 	float screen_space_roughness_limiter_limit = 0.18;
 
 	mutable RID_Owner<RenderBuffers> render_buffers_owner;

servers/rendering/renderer_rd/shaders/scene_forward_clustered.glsl

@@ -895,12 +895,13 @@ void main() {
 
 #ifdef NORMAL_USED
 	if (scene_data.roughness_limiter_enabled) {
-		//https://www.jp.square-enix.com/tech/library/pdf/ImprovedGeometricSpecularAA.pdf
+		// https://www.jp.square-enix.com/tech/library/pdf/ImprovedGeometricSpecularAA.pdf
+		// https://www.jcgt.org/published/0010/02/02/paper.pdf
 		float roughness2 = roughness * roughness;
 		vec3 dndu = dFdx(normal), dndv = dFdy(normal);
-		float variance = scene_data.roughness_limiter_amount * (dot(dndu, dndu) + dot(dndv, dndv));
-		float kernelRoughness2 = min(2.0 * variance, scene_data.roughness_limiter_limit); //limit effect
-		float filteredRoughness2 = min(1.0, roughness2 + kernelRoughness2);
+		float variance = 2.0 * scene_data.roughness_limiter_amount * (dot(dndu, dndu) + dot(dndv, dndv));
+		float kernelRoughness2 = min(variance, scene_data.roughness_limiter_limit);
+		float filteredRoughness2 = clamp(roughness2 + kernelRoughness2, 0.0, 1.0);
 		roughness = sqrt(filteredRoughness2);
 	}
 #endif

servers/rendering_server.cpp

@@ -2924,9 +2924,9 @@ RenderingServer::RenderingServer() {
 	ProjectSettings::get_singleton()->set_custom_property_info("rendering/environment/ssil/fadeout_to", PropertyInfo(Variant::FLOAT, "rendering/environment/ssil/fadeout_to", PROPERTY_HINT_RANGE, "64,65536,0.1,or_greater"));
 
 	GLOBAL_DEF("rendering/anti_aliasing/screen_space_roughness_limiter/enabled", true);
-	GLOBAL_DEF("rendering/anti_aliasing/screen_space_roughness_limiter/amount", 0.25);
+	GLOBAL_DEF("rendering/anti_aliasing/screen_space_roughness_limiter/amount", 0.15915494);
 	GLOBAL_DEF("rendering/anti_aliasing/screen_space_roughness_limiter/limit", 0.18);
-	ProjectSettings::get_singleton()->set_custom_property_info("rendering/anti_aliasing/screen_space_roughness_limiter/amount", PropertyInfo(Variant::FLOAT, "rendering/anti_aliasing/screen_space_roughness_limiter/amount", PROPERTY_HINT_RANGE, "0.01,4.0,0.01"));
+	ProjectSettings::get_singleton()->set_custom_property_info("rendering/anti_aliasing/screen_space_roughness_limiter/amount", PropertyInfo(Variant::FLOAT, "rendering/anti_aliasing/screen_space_roughness_limiter/amount", PROPERTY_HINT_RANGE, "0.01,4.0,0.00000001"));
 	ProjectSettings::get_singleton()->set_custom_property_info("rendering/anti_aliasing/screen_space_roughness_limiter/limit", PropertyInfo(Variant::FLOAT, "rendering/anti_aliasing/screen_space_roughness_limiter/limit", PROPERTY_HINT_RANGE, "0.01,1.0,0.01"));
 
 	GLOBAL_DEF_RST("rendering/scaling_3d/mode", 0);