[RND-175][URP-964] SSAO Improvements

This PR improves the existing SSAO renderer feature in URP. 
We wanted to give users more options to control performance vs quality. 

New AO Method dropdown
  * Interleaved Gradient Noise (Original method)
  * Blue Noise (New)

New Blur Quality Dropdown
  * High: Bilateral (Original method)
  * Medium: Gaussian (New)
  * Low: Single-Pass Kawase (New)

Improved DownSampling:
It will now not only affect the AO pass but also the blur passes

New Samples Dropdown:
High(12), Medium(8) and Low(4) giving ~10-15% performance gain

New Falloff Field:
Option to control the falloff so the AO pass can early out and skip unnecessary work

Merged passes:
Merging of the AfterOpaque and the last blur passes

New AO Depth test:
To avoid casting AO in incorrect places.

Packages/com.unity.render-pipelines.universal/Editor/RendererFeatures/ScreenSpaceAmbientOcclusionEditor.cs

@@ -8,75 +8,126 @@ namespace UnityEditor.Rendering.Universal
     internal class ScreenSpaceAmbientOcclusionEditor : Editor
     {
         #region Serialized Properties
+        private SerializedProperty m_AOMethod;
         private SerializedProperty m_Downsample;
         private SerializedProperty m_AfterOpaque;
         private SerializedProperty m_Source;
         private SerializedProperty m_NormalQuality;
         private SerializedProperty m_Intensity;
         private SerializedProperty m_DirectLightingStrength;
         private SerializedProperty m_Radius;
-        private SerializedProperty m_SampleCount;
+        private SerializedProperty m_Falloff;
+        private SerializedProperty m_Samples;
+        private SerializedProperty m_BlurQuality;
         #endregion
 
         private bool m_IsInitialized = false;
+        private HeaderBool m_ShowQualitySettings;
+
+        class HeaderBool
+        {
+            private string key;
+            public bool value;
+
+            internal HeaderBool(string _key, bool _default = false)
+            {
+                key = _key;
+                if (EditorPrefs.HasKey(key))
+                    value = EditorPrefs.GetBool(key);
+                else
+                    value = _default;
+                EditorPrefs.SetBool(key, value);
+            }
+
+            internal void SetValue(bool newValue)
+            {
+                value = newValue;
+                EditorPrefs.SetBool(key, value);
+            }
+        }
+
 
         // Structs
         private struct Styles
         {
-            public static GUIContent Downsample = EditorGUIUtility.TrTextContent("Downsample", "With this option enabled, Unity downsamples the SSAO effect texture to improve performance. Each dimension of the texture is reduced by a factor of 2.");
-            public static GUIContent AfterOpaque = EditorGUIUtility.TrTextContent("After Opaque", "With this option enabled, Unity calculates and apply SSAO after the opaque pass to improve performance on mobile platforms with tiled-based GPU architectures. This is not physically correct.");
-            public static GUIContent Source = EditorGUIUtility.TrTextContent("Source", "The source of the normal vector values.\nDepth Normals: the feature uses the values generated in the Depth Normal prepass.\nDepth: the feature reconstructs the normal values using the depth buffer.\nIn the Deferred rendering path, the feature uses the G-buffer normals texture.");
-            public static GUIContent NormalQuality = new GUIContent("Normal Quality", "The number of depth texture samples that Unity takes when computing the normals. Low:1 sample, Medium: 5 samples, High: 9 samples.");
+            public static GUIContent AOMethod = EditorGUIUtility.TrTextContent("Method", "The noise method to use when calculating the Ambient Occlusion value.");
             public static GUIContent Intensity = EditorGUIUtility.TrTextContent("Intensity", "The degree of darkness that Ambient Occlusion adds.");
-            public static GUIContent DirectLightingStrength = EditorGUIUtility.TrTextContent("Direct Lighting Strength", "Controls how much the ambient occlusion affects direct lighting.");
             public static GUIContent Radius = EditorGUIUtility.TrTextContent("Radius", "The radius around a given point, where Unity calculates and applies the effect.");
-            public static GUIContent SampleCount = EditorGUIUtility.TrTextContent("Sample Count", "The number of samples that Unity takes when calculating the obscurance value. Higher values have high performance impact.");
+            public static GUIContent Falloff = EditorGUIUtility.TrTextContent("Falloff Distance", "The distance from the camera where Ambient Occlusion should be visible.");
+            public static GUIContent DirectLightingStrength = EditorGUIUtility.TrTextContent("Direct Lighting Strength", "Controls how much the ambient occlusion affects direct lighting.");
+
+            public static GUIContent Quality = EditorGUIUtility.TrTextContent("Quality", "");
+            public static GUIContent Source = EditorGUIUtility.TrTextContent("Source", "The source of the normal vector values.\nDepth Normals: the feature uses the values generated in the Depth Normal prepass.\nDepth: the feature reconstructs the normal values using the depth buffer.\nIn the Deferred rendering path, the feature uses the G-buffer normals texture.");
+            public static GUIContent NormalQuality = new GUIContent("Normal Quality", "The number of depth texture samples that Unity takes when computing the normals. Low:1 sample, Medium: 5 samples, High: 9 samples.");
+            public static GUIContent Downsample = EditorGUIUtility.TrTextContent("Downsample", "With this option enabled, Unity downsamples the SSAO effect texture to improve performance. Each dimension of the texture is reduced by a factor of 2.");
+            public static GUIContent AfterOpaque = EditorGUIUtility.TrTextContent("After Opaque", "With this option enabled, Unity calculates and apply SSAO after the opaque pass to improve performance on mobile platforms with tiled-based GPU architectures. This is not physically correct.");
+            public static GUIContent BlurQuality = EditorGUIUtility.TrTextContent("Blur Quality", "High: Bilateral, Medium: Gaussian. Low: Kawase (Single Pass).");
+            public static GUIContent Samples = EditorGUIUtility.TrTextContent("Samples", "The number of samples that Unity takes when calculating the obscurance value. Low:4 samples, Medium: 8 samples, High: 12 samples.");
         }
 
         private void Init()
         {
+            m_ShowQualitySettings = new HeaderBool($"SSAO.QualityFoldout", false);
+
             SerializedProperty settings = serializedObject.FindProperty("m_Settings");
+
+            m_AOMethod = settings.FindPropertyRelative("AOMethod");
+            m_Intensity = settings.FindPropertyRelative("Intensity");
+            m_Radius = settings.FindPropertyRelative("Radius");
+            m_Falloff = settings.FindPropertyRelative("Falloff");
+            m_DirectLightingStrength = settings.FindPropertyRelative("DirectLightingStrength");
+
             m_Source = settings.FindPropertyRelative("Source");
+            m_NormalQuality = settings.FindPropertyRelative("NormalSamples");
             m_Downsample = settings.FindPropertyRelative("Downsample");
             m_AfterOpaque = settings.FindPropertyRelative("AfterOpaque");
-            m_NormalQuality = settings.FindPropertyRelative("NormalSamples");
-            m_Intensity = settings.FindPropertyRelative("Intensity");
-            m_DirectLightingStrength = settings.FindPropertyRelative("DirectLightingStrength");
-            m_Radius = settings.FindPropertyRelative("Radius");
-            m_SampleCount = settings.FindPropertyRelative("SampleCount");
+            m_BlurQuality = settings.FindPropertyRelative("BlurQuality");
+            m_Samples = settings.FindPropertyRelative("Samples");
+
             m_IsInitialized = true;
         }
 
         public override void OnInspectorGUI()
         {
             if (!m_IsInitialized)
-            {
                 Init();
-            }
 
-            bool isDeferredRenderingMode = RendererIsDeferred();
+            EditorGUILayout.PropertyField(m_AOMethod, Styles.AOMethod);
+            EditorGUILayout.PropertyField(m_Intensity, Styles.Intensity);
+            EditorGUILayout.PropertyField(m_Radius, Styles.Radius);
+            EditorGUILayout.PropertyField(m_Falloff, Styles.Falloff);
+            m_DirectLightingStrength.floatValue = EditorGUILayout.Slider(Styles.DirectLightingStrength, m_DirectLightingStrength.floatValue, 0f, 1f);
 
-            EditorGUILayout.PropertyField(m_Downsample, Styles.Downsample);
+            // Make sure these fields are never below 0.0...
+            m_Intensity.floatValue = Mathf.Max(m_Intensity.floatValue, 0f);
+            m_Radius.floatValue = Mathf.Max(m_Radius.floatValue, 0f);
+            m_Falloff.floatValue = Mathf.Max(m_Falloff.floatValue, 0f);
 
-            EditorGUILayout.PropertyField(m_AfterOpaque, Styles.AfterOpaque);
+            m_ShowQualitySettings.SetValue(EditorGUILayout.Foldout(m_ShowQualitySettings.value, Styles.Quality));
+            if (m_ShowQualitySettings.value)
+            {
+                bool isDeferredRenderingMode = RendererIsDeferred();
 
-            GUI.enabled = !isDeferredRenderingMode;
-            EditorGUILayout.PropertyField(m_Source, Styles.Source);
+                EditorGUI.indentLevel++;
 
-            // We only enable this field when depth source is selected
-            GUI.enabled = !isDeferredRenderingMode && m_Source.enumValueIndex == (int)ScreenSpaceAmbientOcclusionSettings.DepthSource.Depth;
-            EditorGUI.indentLevel++;
-            EditorGUILayout.PropertyField(m_NormalQuality, Styles.NormalQuality);
-            EditorGUI.indentLevel--;
-            GUI.enabled = true;
+                // Selecting source is not available for Deferred Rendering...
+                GUI.enabled = !isDeferredRenderingMode;
+                EditorGUILayout.PropertyField(m_Source, Styles.Source);
 
-            EditorGUILayout.PropertyField(m_Intensity, Styles.Intensity);
-            EditorGUILayout.PropertyField(m_Radius, Styles.Radius);
-            m_DirectLightingStrength.floatValue = EditorGUILayout.Slider(Styles.DirectLightingStrength, m_DirectLightingStrength.floatValue, 0f, 1f);
-            m_SampleCount.intValue = EditorGUILayout.IntSlider(Styles.SampleCount, m_SampleCount.intValue, 4, 20);
+                // We only enable this field when depth source is selected...
+                GUI.enabled = !isDeferredRenderingMode && m_Source.enumValueIndex == (int)ScreenSpaceAmbientOcclusionSettings.DepthSource.Depth;
+                EditorGUI.indentLevel++;
+                EditorGUILayout.PropertyField(m_NormalQuality, Styles.NormalQuality);
+                EditorGUI.indentLevel--;
+                GUI.enabled = true;
 
-            m_Intensity.floatValue = Mathf.Clamp(m_Intensity.floatValue, 0f, m_Intensity.floatValue);
-            m_Radius.floatValue = Mathf.Clamp(m_Radius.floatValue, 0f, m_Radius.floatValue);
+                EditorGUILayout.PropertyField(m_Downsample, Styles.Downsample);
+                EditorGUILayout.PropertyField(m_AfterOpaque, Styles.AfterOpaque);
+                EditorGUILayout.PropertyField(m_BlurQuality, Styles.BlurQuality);
+                EditorGUILayout.PropertyField(m_Samples, Styles.Samples);
+
+                EditorGUI.indentLevel--;
+            }
         }
 
         private bool RendererIsDeferred()
@@ -97,10 +148,8 @@ private bool RendererIsDeferred()
 
                 var rendererFeatures = rendererData.rendererFeatures;
                 foreach (var feature in rendererFeatures)
-                {
                     if (feature is ScreenSpaceAmbientOcclusion && (ScreenSpaceAmbientOcclusion)feature == ssaoFeature)
                         return rendererData is UniversalRendererData && ((UniversalRendererData)rendererData).renderingMode == RenderingMode.Deferred;
-                }
             }
 
             return false;

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/UnlitPass.hlsl

@@ -75,9 +75,14 @@ void frag(
     //SETUP_DEBUG_TEXTURE_DATA(inputData, input.texCoord1, _MainTex);
 
     half4 finalColor = UniversalFragmentUnlit(inputData, surfaceDescription.BaseColor, alpha);
-
     finalColor.a = OutputAlpha(finalColor.a, isTransparent);
 
+    #if defined(_SCREEN_SPACE_OCCLUSION) && !defined(_SURFACE_TYPE_TRANSPARENT)
+        float2 normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(unpacked.positionCS);
+        AmbientOcclusionFactor aoFactor = GetScreenSpaceAmbientOcclusion(normalizedScreenSpaceUV);
+        finalColor.rgb *= aoFactor.directAmbientOcclusion;
+    #endif
+
     outColor = finalColor;
 
 #ifdef _WRITE_RENDERING_LAYERS

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Targets/UniversalLitSubTarget.cs

@@ -864,19 +864,9 @@ static class LitKeywords
                 scope = KeywordScope.Local,
             };
 
-            public static readonly KeywordDescriptor ScreenSpaceAmbientOcclusion = new KeywordDescriptor()
-            {
-                displayName = "Screen Space Ambient Occlusion",
-                referenceName = "_SCREEN_SPACE_OCCLUSION",
-                type = KeywordType.Boolean,
-                definition = KeywordDefinition.MultiCompile,
-                scope = KeywordScope.Global,
-                stages = KeywordShaderStage.Fragment,
-            };
-
             public static readonly KeywordCollection Forward = new KeywordCollection
             {
-                { ScreenSpaceAmbientOcclusion },
+                { CoreKeywordDescriptors.ScreenSpaceAmbientOcclusion },
                 { CoreKeywordDescriptors.StaticLightmap },
                 { CoreKeywordDescriptors.DynamicLightmap },
                 { CoreKeywordDescriptors.DirectionalLightmapCombined },

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Targets/UniversalTarget.cs

@@ -968,7 +968,7 @@ public static PassDescriptor DepthNormalOnly(UniversalTarget target)
                 renderStates = CoreRenderStates.DepthNormalsOnly(target),
                 pragmas = CorePragmas.Instanced,
                 defines = new DefineCollection(),
-                keywords = new KeywordCollection(),
+                keywords = new KeywordCollection() { CoreKeywordDescriptors.GBufferNormalsOct },
                 includes = CoreIncludes.DepthNormalsOnly,
 
                 // Custom Interpolator Support
@@ -2029,6 +2029,16 @@ static class CoreKeywordDescriptors
             scope = KeywordScope.Global,
             stages = KeywordShaderStage.Fragment,
         };
+
+        public static readonly KeywordDescriptor ScreenSpaceAmbientOcclusion = new KeywordDescriptor()
+        {
+            displayName = "Screen Space Ambient Occlusion",
+            referenceName = "_SCREEN_SPACE_OCCLUSION",
+            type = KeywordType.Boolean,
+            definition = KeywordDefinition.MultiCompile,
+            scope = KeywordScope.Global,
+            stages = KeywordShaderStage.Fragment,
+        };
     }
     #endregion
 

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Targets/UniversalUnlitSubTarget.cs

@@ -268,7 +268,7 @@ public static PassDescriptor DepthNormalOnly(UniversalTarget target)
                 var result = new PassDescriptor
                 {
                     // Definition
-                    displayName = "DepthNormals",
+                    displayName = "DepthNormalsOnly",
                     referenceName = "SHADERPASS_DEPTHNORMALSONLY",
                     lightMode = "DepthNormalsOnly",
                     useInPreview = false,
@@ -290,7 +290,7 @@ public static PassDescriptor DepthNormalOnly(UniversalTarget target)
                     renderStates = CoreRenderStates.DepthNormalsOnly(target),
                     pragmas = CorePragmas.Forward,
                     defines = new DefineCollection(),
-                    keywords = new KeywordCollection() { CoreKeywords.DOTSDepthNormal },
+                    keywords = new KeywordCollection() { CoreKeywords.DOTSDepthNormal, CoreKeywordDescriptors.GBufferNormalsOct },
                     includes = CoreIncludes.DepthNormalsOnly,
 
                     // Custom Interpolator Support
@@ -346,6 +346,7 @@ static class UnlitKeywords
                 CoreKeywordDescriptors.SampleGI,
                 CoreKeywordDescriptors.DBuffer,
                 CoreKeywordDescriptors.DebugDisplay,
+                CoreKeywordDescriptors.ScreenSpaceAmbientOcclusion,
             };
 
             public static readonly KeywordCollection DOTSForward = new KeywordCollection