Fix voronoi and gradient noise when using half precision

com.unity.shadergraph/CHANGELOG.md

@@ -31,6 +31,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Copied nodes are now pasted at the cursor location instead of slightly offset from their original location
 - Error messages reported on Sub Graph output nodes for invalid previews now present clearer information, with documentation support.
 - Updated legacy COLOR output semantic to SV_Target in pixel shader for compatibility with DXC
+- Changed the Voronoi Node algorithm to increase the useful range of the input values and to always use float values internally to avoid clipping.
 - Changed the `Reference Suffix` of Keyword Enum entries so that you cannot edit them, which ensures that material keywords compile properly. 
 
 ### Fixed

com.unity.shadergraph/Editor/Data/Nodes/Procedural/Noise/GradientNoiseNode.cs

@@ -45,7 +45,8 @@ public override void GenerateNodeFunction(FunctionRegistry registry, GenerationM
 {
     // Permutation and hashing used in webgl-nosie goo.gl/pX7HtC
     p = p % 289;
-    $precision x = (34 * p.x + 1) * p.x % 289 + p.y;
+    // need full precision, otherwise half overflows when p > 1
+    float x = float(34 * p.x + 1) * p.x % 289 + p.y;
     x = (34 * x + 1) * x % 289;
     x = frac(x / 41) * 2 - 1;
     return normalize($precision2(x - floor(x + 0.5), abs(x) - 0.5));

com.unity.shadergraph/Editor/Data/Nodes/Procedural/Noise/VoronoiNode.cs

@@ -58,7 +58,7 @@ public override void GenerateNodeFunction(FunctionRegistry registry, GenerationM
 inline $precision2 Unity_Voronoi_RandomVector_$precision ($precision2 UV, $precision offset)
 {
     $precision2x2 m = $precision2x2(15.27, 47.63, 99.41, 89.98);
-    UV = frac(sin(mul(UV, m)) * 46839.32);
+    UV = frac(sin(mul(UV, m)));
     return $precision2(sin(UV.y*+offset)*0.5+0.5, cos(UV.x*offset)*0.5+0.5);
 }
 "));