Add debug decal atlas view.

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Debug/DebugDisplay.cs

         public static string k_PanelRendering = "Rendering";
 
         public static string k_PanelScreenSpaceTracing = "Screen Space Tracing";
+        public static string k_PanelDecals = "Decals";
 
         //static readonly string[] k_HiZIntersectionKind = { "None", "Depth", "Cell" };
 
         DebugUI.Widget[] m_DebugRenderingItems;
         DebugUI.Widget[] m_DebugScreenSpaceTracingItems;
+        DebugUI.Widget[] m_DebugDecalsItems;
 
 
         public float debugOverlayRatio = 0.33f;
         public LightingDebugSettings lightingDebugSettings = new LightingDebugSettings();
         public MipMapDebugSettings mipMapDebugSettings = new MipMapDebugSettings();
         public ColorPickerDebugSettings colorPickerDebugSettings = new ColorPickerDebugSettings();
+        public DecalsDebugSettings decalsDebugSettings = new DecalsDebugSettings();
 
         public static GUIContent[] lightingFullScreenDebugStrings = null;
         public static int[] lightingFullScreenDebugValues = null;
             RegisterScreenSpaceTracingDebug();
         }
 
+        void RefreshDecalsDebug<T>(DebugUI.Field<T> field, T value)
+        {
+            UnregisterDebugItems(k_PanelDecals, m_DebugDecalsItems);
+            RegisterDecalsDebug();
+        }
+
         public void RegisterLightingDebug()
         {
             var list = new List<DebugUI.Widget>();
             panel.children.Add(m_DebugRenderingItems);
         }
 
+        public void RegisterDecalsDebug()
+        {
+            m_DebugDecalsItems = new DebugUI.Widget[]
+            {
+                new DebugUI.BoolField { displayName = "Display atlas", getter = () => decalsDebugSettings.m_DisplayAtlas, setter = value => decalsDebugSettings.m_DisplayAtlas = value},
+                new DebugUI.UIntField { displayName = "Mip Level", getter = () => decalsDebugSettings.m_MipLevel, setter = value => decalsDebugSettings.m_MipLevel = value, min = () => 0u, max = () => (uint)(RenderPipelineManager.currentPipeline as HDRenderPipeline).GetDecalAtlasMipCount() }
+            };
+
+            var panel = DebugManager.instance.GetPanel(k_PanelDecals, true);
+            panel.children.Add(m_DebugDecalsItems);
+        }
+
+            RegisterDecalsDebug();
             RegisterDisplayStatsDebug();
             RegisterMaterialDebug();
             RegisterLightingDebug();
 
         public void UnregisterDebug()
         {
+            UnregisterDebugItems(k_PanelDecals, m_DebugDecalsItems);
             UnregisterDebugItems(k_PanelDisplayStats, m_DebugDisplayStatsItems);
             UnregisterDebugItems(k_PanelMaterials, m_DebugMaterialItems);
             UnregisterDebugItems(k_PanelLighting, m_DebugLightingItems);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Decal/DecalSystem.cs

                 }
             }
 
-           
-           
-
             public void RenderIntoDBuffer(CommandBuffer cmd)
             {
                 if(m_NumResults == 0)
             // set to null so that they get recreated
             m_DecalMesh = null;
             m_Atlas = null;
+        }
+
+        public void RenderDebugOverlay(HDCamera hdCamera, CommandBuffer cmd, DebugDisplaySettings debugDisplaySettings, ref float x, ref float y, float overlaySize, float width)
+        {
+            if(debugDisplaySettings.decalsDebugSettings.m_DisplayAtlas)
+            { 
+                using (new ProfilingSample(cmd, "Display Decal Atlas", CustomSamplerId.DisplayDebugDecalsAtlas.GetSampler()))
+                {
+                    HDUtils.BlitQuad(cmd, Atlas.AtlasTexture, new Vector4(1,1,0,0), new Vector4(width / hdCamera.actualWidth, overlaySize / hdCamera.actualHeight, x / hdCamera.actualWidth, y / hdCamera.actualHeight), (int)debugDisplaySettings.decalsDebugSettings.m_MipLevel, true);
+                    HDUtils.NextOverlayCoord(ref x, ref y, overlaySize, overlaySize, hdCamera.actualWidth);
+                }
+            }
         }
     }
 }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDCustomSamplerId.cs

         GBuffer,
         DBufferRender,
         DBufferPrepareDrawData,
+        DisplayDebugDecalsAtlas,
         DisplayDebugViewMaterial,
         DebugViewMaterialGBuffer,
         BlitDebugViewMaterialDebug,

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDRenderPipeline.cs

 
         public int GetCurrentShadowCount() { return m_LightLoop.GetCurrentShadowCount(); }
         public int GetShadowAtlasCount() { return m_LightLoop.GetShadowAtlasCount(); }
+        public int GetDecalAtlasMipCount()
+        {
+            int highestDim = Math.Max(renderPipelineSettings.decalSettings.atlasWidth, renderPipelineSettings.decalSettings.atlasHeight);
+            return (int)Math.Log(highestDim, 2);
+        }
+
         public int GetShadowSliceCount(uint atlasIndex) { return m_LightLoop.GetShadowSliceCount(atlasIndex); }
 
         readonly SkyManager m_SkyManager = new SkyManager();
                 }
 
                 m_LightLoop.RenderDebugOverlay(hdCamera, cmd, m_CurrentDebugDisplaySettings, ref x, ref y, overlaySize, hdCamera.actualWidth);
+
+                DecalSystem.instance.RenderDebugOverlay(hdCamera, cmd, m_CurrentDebugDisplaySettings, ref x, ref y, overlaySize, hdCamera.actualWidth);
 
                 if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None)
                 {

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Debug/DecalsDebug.cs

+using System;
+
+namespace UnityEngine.Experimental.Rendering.HDPipeline
+{
+    [Serializable]
+    public class DecalsDebugSettings
+    {
+        public bool m_DisplayAtlas = false;
+        public UInt32 m_MipLevel = 0;
+    }
+}

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Debug/DecalsDebug.cs.meta

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