Merge pull request #1856 from Unity-Technologies/Add-warnign-message

Add warning message for platform not supported

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

 
 ## [3.3.0-preview]
 
+### Added
+- Added an error message to say to use Metal or Vulkan when trying to use OpenGL API
+
 ### Fixed
 - Fix an issue where the screen where darken when rendering camera preview
 - Fix display correct target platform when showing message to inform user that a platform is not supported

com.unity.render-pipelines.high-definition/HDRP/RenderPipeline/HDRenderPipeline.cs

             {
                 CoreUtils.DisplayUnsupportedAPIMessage();
 
+                // Display more information to the users when it should have use Metal instead of OpenGL
+                if (SystemInfo.graphicsDeviceType.ToString().StartsWith("OpenGL"))
+                {
+                    if (SystemInfo.operatingSystem.StartsWith("Mac"))
+                        CoreUtils.DisplayUnsupportedMessage("Use Metal API instead.");
+                    else if (SystemInfo.operatingSystem.StartsWith("Windows"))
+                        CoreUtils.DisplayUnsupportedMessage("Use Vulkan API instead.");
+                }
+
                 return false;
             }