Added an option in Lighting debug to display the sky reflection probe cubemap.

Assets/ScriptableRenderPipeline/HDRenderPipeline/Debug/HDRenderPipelineDebug.cs

         public float                overrideSmoothnessValue = 0.5f;
         public Color                debugLightingAlbedo = new Color(0.5f, 0.5f, 0.5f);
 
+        public bool                 displaySkyReflection = false;
+        public float                skyReflectionMipmap = 0.0f;
+
+            skyReflectionMipmap = Mathf.Clamp(skyReflectionMipmap, 0.0f, 1.0f);
         }
     }
 }

Assets/ScriptableRenderPipeline/HDRenderPipeline/Editor/HDRenderPipelineInspector.cs

             public readonly GUIContent lightingDebugOverrideSmoothness = new GUIContent("Override Smoothness");
             public readonly GUIContent lightingDebugOverrideSmoothnessValue = new GUIContent("Smoothness Value");
             public readonly GUIContent lightingDebugAlbedo = new GUIContent("Lighting Debug Albedo");
+            public readonly GUIContent lightingDisplaySkyReflection = new GUIContent("Display Sky Reflection");
+            public readonly GUIContent lightingDisplaySkyReflectionMipmap = new GUIContent("Reflection Mipmap");
 
             public Styles()
             {
         SerializedProperty m_LightingDebugOverrideSmoothness = null;
         SerializedProperty m_LightingDebugOverrideSmoothnessValue = null;
         SerializedProperty m_LightingDebugAlbedo = null;
+        SerializedProperty m_LightingDebugDisplaySkyReflection = null;
+        SerializedProperty m_LightingDebugDisplaySkyReflectionMipmap = null;
 
         // Rendering Settings
         SerializedProperty m_RenderingUseForwardOnly = null;
             m_LightingDebugOverrideSmoothness = FindProperty(x => x.globalDebugSettings.lightingDebugSettings.overrideSmoothness);
             m_LightingDebugOverrideSmoothnessValue = FindProperty(x => x.globalDebugSettings.lightingDebugSettings.overrideSmoothnessValue);
             m_LightingDebugAlbedo = FindProperty(x => x.globalDebugSettings.lightingDebugSettings.debugLightingAlbedo);
+            m_LightingDebugDisplaySkyReflection = FindProperty(x => x.globalDebugSettings.lightingDebugSettings.displaySkyReflection);
+            m_LightingDebugDisplaySkyReflectionMipmap = FindProperty(x => x.globalDebugSettings.lightingDebugSettings.skyReflectionMipmap);
 
             // Rendering settings
             m_RenderingUseForwardOnly = FindProperty(x => x.renderingSettings.useForwardRenderingOnly);
             if (!m_LightingDebugMode.hasMultipleDifferentValues)
             {
                 if ((LightingDebugMode)m_LightingDebugMode.intValue != LightingDebugMode.None)
-            {
+                {
-                {
+                    {
                         EditorGUI.indentLevel++;
                         EditorGUILayout.PropertyField(m_LightingDebugOverrideSmoothnessValue, styles.lightingDebugOverrideSmoothnessValue);
                         EditorGUI.indentLevel--;
             }
+
+            EditorGUILayout.PropertyField(m_LightingDebugDisplaySkyReflection, styles.lightingDisplaySkyReflection);
+            if (!m_LightingDebugDisplaySkyReflection.hasMultipleDifferentValues && m_LightingDebugDisplaySkyReflection.boolValue == true)
+            {
+                EditorGUI.indentLevel++;
+                EditorGUILayout.PropertyField(m_LightingDebugDisplaySkyReflectionMipmap, styles.lightingDisplaySkyReflectionMipmap);
+                EditorGUI.indentLevel--;
+            }
+
             EditorGUI.indentLevel--;
 
             if (EditorGUI.EndChangeCheck())

Assets/ScriptableRenderPipeline/HDRenderPipeline/HDRenderPipeline.cs

         readonly GBufferManager m_gbufferManager = new GBufferManager();
 
         // Various set of material use in render loop
-        readonly Material m_DebugViewMaterialGBuffer;
-        readonly Material m_DebugDisplayShadowMap;
-
+        
+        private Material m_DebugDisplayShadowMap;
+        private Material m_DebugViewMaterialGBuffer;
+        private Material m_DebugDisplayLatlong;
+        
         // Various buffer
         readonly int m_CameraColorBuffer;
         readonly int m_CameraSubsurfaceBuffer;
             m_CameraColorBufferRT               = new RenderTargetIdentifier(m_CameraColorBuffer);
             m_CameraSubsurfaceBufferRT          = new RenderTargetIdentifier(m_CameraSubsurfaceBuffer);
             m_CameraFilteringBufferRT           = new RenderTargetIdentifier(m_CameraFilteringBuffer);
-
-            m_DebugViewMaterialGBuffer = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DebugViewMaterialGBuffer");
 
             m_FilterSubsurfaceScattering = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/CombineSubsurfaceScattering");
             m_FilterSubsurfaceScattering.DisableKeyword("FILTER_HORIZONTAL");
             m_FilterSubsurfaceScattering.EnableKeyword("FILTER_HORIZONTAL");
             m_FilterAndCombineSubsurfaceScattering.SetFloat("_DstBlend", (float)BlendMode.One);
 
-            m_DebugDisplayShadowMap = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DebugDisplayShadowMap");
+            InitializeDebugMaterials();
 
             m_ShadowPass = new ShadowRenderPass(owner.shadowSettings);
 
 
             m_SkyManager.Build();
             m_SkyManager.skySettings = owner.skySettingsToUse;
+        }
+
+        void InitializeDebugMaterials()
+        {
+            m_DebugDisplayShadowMap = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DebugDisplayShadowMap");
+            m_DebugViewMaterialGBuffer = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DebugViewMaterialGBuffer");
+            m_DebugDisplayLatlong = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DebugDisplayLatlong");
         }
 
         public override void Dispose()
 
             MaterialPropertyBlock propertyBlock = new MaterialPropertyBlock();
 
-            LightingDebugSettings shadowDebug = globalDebugSettings.lightingDebugSettings;
+            LightingDebugSettings lightingDebug = globalDebugSettings.lightingDebugSettings;
-            if (shadowDebug.shadowDebugMode != ShadowDebugMode.None)
+            if (lightingDebug.shadowDebugMode != ShadowDebugMode.None)
-                if (shadowDebug.shadowDebugMode == ShadowDebugMode.VisualizeShadowMap)
+                if (lightingDebug.shadowDebugMode == ShadowDebugMode.VisualizeShadowMap)
-                    uint visualizeShadowIndex = Math.Min(shadowDebug.shadowMapIndex, (uint)(GetCurrentShadowCount() - 1));
+                    uint visualizeShadowIndex = Math.Min(lightingDebug.shadowMapIndex, (uint)(GetCurrentShadowCount() - 1));
                     ShadowLight shadowLight = m_ShadowsResult.shadowLights[visualizeShadowIndex];
                     for (int slice = 0; slice < shadowLight.shadowSliceCount; ++slice)
                     {
                         NextOverlayCoord(ref x, ref y, overlaySize, camera.pixelWidth);
                     }
                 }
-                else if (shadowDebug.shadowDebugMode == ShadowDebugMode.VisualizeAtlas)
+                else if (lightingDebug.shadowDebugMode == ShadowDebugMode.VisualizeAtlas)
                 {
                     propertyBlock.SetVector("_TextureScaleBias", new Vector4(1.0f, 1.0f, 0.0f, 0.0f));
 
                     NextOverlayCoord(ref x, ref y, overlaySize, camera.pixelWidth);
                 }
+            }
+
+            if(lightingDebug.displaySkyReflection)
+            {
+                Texture skyReflection = m_SkyManager.skyReflection;
+                propertyBlock.SetTexture("_InputCubemap", skyReflection);
+                propertyBlock.SetFloat("_Mipmap", lightingDebug.skyReflectionMipmap);
+                debugCB.SetViewport(new Rect(x, y, overlaySize, overlaySize));
+                debugCB.DrawProcedural(Matrix4x4.identity, m_DebugDisplayLatlong, 0, MeshTopology.Triangles, 3, 1, propertyBlock);
+                NextOverlayCoord(ref x, ref y, overlaySize, camera.pixelWidth);
             }
 
             renderContext.ExecuteCommandBuffer(debugCB);

Assets/ScriptableRenderPipeline/HDRenderPipeline/Sky/SkyManager.cs

             get { return m_SkySettings; }
         }
 
+        public Texture skyReflection { get { return m_SkyboxGGXCubemapRT; } }
+
         protected Mesh BuildSkyMesh(Vector3 cameraPosition, Matrix4x4 cameraInvViewProjectionMatrix, bool forceUVBottom)
         {
             Vector4 vertData0 = new Vector4(-1.0f, -1.0f, 1.0f, 1.0f);

Assets/ScriptableRenderPipeline/ShaderLibrary/Common.hlsl

     return float2(1.0 - 0.5 * INV_PI * atan2(dir.x, -dir.z), asin(dir.y) * INV_PI + 0.5);
 }
 
+float3 LatlongToDirectionCoordinate(float2 coord)
+{
+    float theta = coord.y * PI;
+    float phi = (coord.x * 2.f * PI - PI*0.5f);
+
+    float cosTheta = cos(theta);
+    float sinTheta = sqrt(1.0f - min(1.0f, cosTheta*cosTheta));
+    float cosPhi = cos(phi);
+    float sinPhi = sin(phi);
+
+    float3 direction = float3(sinTheta*cosPhi, cosTheta, sinTheta*sinPhi);
+    direction.xy *= -1.0;
+    return direction;
+}
+
 // ----------------------------------------------------------------------------
 // World position reconstruction / transformation
 // ----------------------------------------------------------------------------

Assets/ScriptableRenderPipeline/HDRenderPipeline/Debug/Resources/DebugDisplayLatlong.shader

+Shader "Hidden/HDRenderPipeline/DebugDisplayLatlong"
+{
+    SubShader
+    {
+        Pass
+        {
+            ZWrite Off
+            ZTest Off
+            Blend One Zero
+            Cull Off
+
+            HLSLPROGRAM
+            #pragma target 4.5
+            #pragma only_renderers d3d11 ps4 metal // TEMP: unitl we go futher in dev
+
+            #pragma vertex Vert
+            #pragma fragment Frag
+
+            #include "ShaderLibrary/Common.hlsl"
+            #include "ShaderLibrary/ImageBasedLighting.hlsl"
+
+            TEXTURECUBE(_InputCubemap);
+            SAMPLERCUBE(sampler_InputCubemap);
+            float _Mipmap;
+
+            struct Attributes
+            {
+                uint vertexID : SV_VertexID;
+            };
+
+            struct Varyings
+            {
+                float4 positionCS : SV_POSITION;
+                float2 texcoord : TEXCOORD0;
+            };
+
+            Varyings Vert(Attributes input)
+            {
+                Varyings output;
+                output.positionCS = GetFullScreenTriangleVertexPosition(input.vertexID);
+                output.texcoord = GetFullScreenTriangleTexcoord(input.vertexID);// *_TextureScaleBias.xy + _TextureScaleBias.zw;
+
+                return output;
+            }
+
+            float4 Frag(Varyings input) : SV_Target
+            {
+                uint width, height, depth, mipCount;
+                width = height = depth = mipCount = 0;
+                _InputCubemap.GetDimensions(width, height, depth, mipCount);
+                mipCount = clamp(mipCount, 0, UNITY_SPECCUBE_LOD_STEPS);
+                return SAMPLE_TEXTURECUBE_LOD(_InputCubemap, sampler_InputCubemap, LatlongToDirectionCoordinate(input.texcoord.xy), _Mipmap * mipCount);
+            }
+
+            ENDHLSL
+        }
+
+    }
+    Fallback Off
+}

Assets/ScriptableRenderPipeline/HDRenderPipeline/Debug/Resources/DebugDisplayLatlong.shader.meta

+fileFormatVersion: 2
+guid: c1d1d149a043a5349ba367da6c2051ba
+timeCreated: 1476053153
+licenseType: Pro
+ShaderImporter:
+  defaultTextures: []
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
+