Merge pull request #803 from Unity-Technologies/Update-tessellation-factor-limit-to-64

Update tessellation factor limit to 64

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Material/Lit/BaseLitUI.cs

             public static readonly string[] tessellationModeNames = Enum.GetNames(typeof(TessellationMode));
 
             public static GUIContent tessellationText = new GUIContent("Tessellation options", "Tessellation options");
-            public static GUIContent tessellationFactorText = new GUIContent("Tessellation factor", "This value is the tessellation factor use for tessellation, higher mean more tessellated");
+            public static GUIContent tessellationFactorText = new GUIContent("Tessellation factor", "This value is the tessellation factor use for tessellation, higher mean more tessellated. Above 15 is costly. Maximum tessellation factor is 15 on XBone / PS4");
             public static GUIContent tessellationFactorMinDistanceText = new GUIContent("Start fade distance", "Distance (in unity unit) at which the tessellation start to fade out. Must be inferior at Max distance");
             public static GUIContent tessellationFactorMaxDistanceText = new GUIContent("End fade distance", "Maximum distance (in unity unit) to the camera where triangle are tessellated");
             public static GUIContent tessellationFactorTriangleSizeText = new GUIContent("Triangle size", "Desired screen space sized of triangle (in pixel). Smaller value mean smaller triangle.");

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLitTessellation.shader

 
         // Tessellation specific
         [Enum(None, 0, Phong, 1)] _TessellationMode("Tessellation mode", Float) = 0
-        _TessellationFactor("Tessellation Factor", Range(0.0, 15.0)) = 4.0
+        _TessellationFactor("Tessellation Factor", Range(0.0, 64.0)) = 4.0
         _TessellationFactorMinDistance("Tessellation start fading distance", Float) = 20.0
         _TessellationFactorMaxDistance("Tessellation end fading distance", Float) = 50.0
         _TessellationFactorTriangleSize("Tessellation triangle size", Float) = 100.0

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/LitTessellation.shader

 
         // Tessellation specific
         [Enum(None, 0, Phong, 1)] _TessellationMode("Tessellation mode", Float) = 0
-        _TessellationFactor("Tessellation Factor", Range(0.0, 15.0)) = 4.0
+        _TessellationFactor("Tessellation Factor", Range(0.0, 64.0)) = 4.0
         _TessellationFactorMinDistance("Tessellation start fading distance", Float) = 20.0
         _TessellationFactorMaxDistance("Tessellation end fading distance", Float) = 50.0
         _TessellationFactorTriangleSize("Tessellation triangle size", Float) = 100.0

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderPass/TessellationShare.hlsl

+#if defined(SHADER_API_XBOXONE) || defined(SHADER_API_PSSL)
+#else
+#define MAX_TESSELLATION_FACTORS 64.0
+#endif
 
 struct TessellationFactors
 {