Display Info Box when MSAA + ray tracing is onr (#4627)

* Show info box when ray tracing is enabled.

* Changelog

* Move below MSAA

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -278,6 +278,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Global Camera shader constants are now pushed when doing a custom render callback.
 - Splited HDProjectSettings with new HDUserSettings in UserProject. Now Wizard working variable should not bother versioning tool anymore (case 1330640)
 - Removed redundant Show Inactive Objects and Isolate Selection checkboxes from the Emissive Materials tab of the Light Explorer (case 1331750).
+- Display an info box and disable MSAA  asset entry when ray tracing is enabled.
 
 ## [11.0.0] - 2020-10-21
 

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/HDRenderPipelineUI.Skin.cs

@@ -147,6 +147,7 @@ public class Styles
             public static readonly GUIContent supportedRayTracingMode = EditorGUIUtility.TrTextContent("Supported Ray Tracing Mode (Preview)");
             public static readonly GUIContent rayTracingUnsupportedWarning = EditorGUIUtility.TrTextContent("Ray tracing is not supported on your device. Please refer to the documentation.");
             public static readonly GUIContent rayTracingDX12OnlyWarning = EditorGUIUtility.TrTextContent("Ray tracing is currently only supported on DX12.");
+            public static readonly GUIContent rayTracingMSAAUnsupported = EditorGUIUtility.TrTextContent("When Ray tracing is enabled in asset, MSAA is not supported. Please refer to the documentation.");
             public static readonly GUIContent maximumLODLevel = EditorGUIUtility.TrTextContent("Maximum LOD Level");
             public static readonly GUIContent LODBias = EditorGUIUtility.TrTextContent("LOD Bias");
             public static readonly GUIContent supportProbeVolumeContent = EditorGUIUtility.TrTextContent("Enable", "When enabled, HDRP allocates Shader variants and memory for probe volume based GI. This allows you to use probe volumes in your Unity Project.");

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/HDRenderPipelineUI.cs

@@ -1138,17 +1138,26 @@ static void Drawer_SectionRenderingUnsorted(SerializedHDRenderPipelineAsset seri
             // MSAA is an option that is only available in full forward but Camera can be set in Full Forward only. Thus MSAA have no dependency currently
             //Note: do not use SerializedProperty.enumValueIndex here as this enum not start at 0 as it is used as flags.
             bool msaaAllowed = true;
+            bool hasRayTracing = false;
             for (int index = 0; index < serialized.serializedObject.targetObjects.Length && msaaAllowed; ++index)
             {
-                var litShaderMode = (serialized.serializedObject.targetObjects[index] as HDRenderPipelineAsset).currentPlatformRenderPipelineSettings.supportedLitShaderMode;
-                msaaAllowed &= litShaderMode == SupportedLitShaderMode.ForwardOnly || litShaderMode == SupportedLitShaderMode.Both;
+                var settings = (serialized.serializedObject.targetObjects[index] as HDRenderPipelineAsset).currentPlatformRenderPipelineSettings;
+                var litShaderMode = settings.supportedLitShaderMode;
+                bool rayTracedSupported = settings.supportRayTracing;
+                hasRayTracing |= rayTracedSupported;
+                msaaAllowed &= (litShaderMode == SupportedLitShaderMode.ForwardOnly || litShaderMode == SupportedLitShaderMode.Both) && !rayTracedSupported;
             }
+
             using (new EditorGUI.DisabledScope(!msaaAllowed))
             {
                 ++EditorGUI.indentLevel;
                 EditorGUILayout.PropertyField(serialized.renderPipelineSettings.MSAASampleCount, Styles.MSAASampleCountContent);
                 --EditorGUI.indentLevel;
             }
+            if (hasRayTracing && serialized.renderPipelineSettings.MSAASampleCount.intValue != (int)MSAASamples.None)
+            {
+                EditorGUILayout.HelpBox(Styles.rayTracingMSAAUnsupported.text, MessageType.Info, wide: true);
+            }
 
             EditorGUILayout.PropertyField(serialized.renderPipelineSettings.supportMotionVectors, Styles.supportMotionVectorContent);
             EditorGUILayout.PropertyField(serialized.renderPipelineSettings.supportRuntimeDebugDisplay, Styles.supportRuntimeDebugDisplayContent);