Fix Construct Matrix on GPU (#102)

* Fix VFXExpressionVector3sToMatrix & VFXExpressionVector4sToMatrix evaluation on GPU

* *Update changelog.md

Author: PaulDemeulenaere

com.unity.visualeffectgraph/CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Normals with non uniform scales are correctly computed [Case 1246989](https://issuetracker.unity3d.com/product/unity/issues/guid/1246989/)
 - Fix exposed Texture2DArray and Cubemap types from shader graph not being taken into account in Output Mesh [Case 1265221](https://issuetracker.unity3d.com/product/unity/issues/guid/1265221/)
 - Allow world position usage in shaderGraph plugged into an alpha/opacity output [Case 1259511](https://issuetracker.unity3d.com/product/unity/issues/guid/1259511/)
+- GPU Evaluation of Construct Matrix
 
 ## [10.0.0] - 2019-06-10
 ### Added

com.unity.visualeffectgraph/Editor/Expressions/VFXExpressionTransform.cs

@@ -557,7 +557,7 @@ sealed protected override VFXExpression Evaluate(VFXExpression[] constParents)
 
         public override string GetCodeString(string[] parents)
         {
-            return string.Format("float4x4(float4({0}, 0.0), float4({1}, 0.0), float4({2}, 0.0), float4({3}, 1.0));", parents[0], parents[1], parents[2], parents[3]);
+            return string.Format("VFXCreateMatrixFromColumns(float4({0}, 0.0), float4({1}, 0.0), float4({2}, 0.0), float4({3}, 1.0));", parents[0], parents[1], parents[2], parents[3]);
         }
     }
 
@@ -603,7 +603,7 @@ sealed protected override VFXExpression Evaluate(VFXExpression[] constParents)
 
         public override string GetCodeString(string[] parents)
         {
-            return string.Format("float4x4({0}, {1}, {2}, {3});", parents[0], parents[1], parents[2], parents[3]);
+            return string.Format("VFXCreateMatrixFromColumns({0}, {1}, {2}, {3});", parents[0], parents[1], parents[2], parents[3]);
         }
     }
 

com.unity.visualeffectgraph/Shaders/VFXCommon.hlsl

@@ -471,6 +471,13 @@ float SampleCurve(float4 curveData, float u)
 ///////////
 // Utils //
 ///////////
+float4x4 VFXCreateMatrixFromColumns(float4 i, float4 j, float4 k, float4 o)
+{
+    return float4x4(i.x, j.x, k.x, o.x,
+                    i.y, j.y, k.y, o.y,
+                    i.z, j.z, k.z, o.z,
+                    i.w, j.w, k.w, o.w);
+}
 
 // Invert 3D transformation matrix (not perspective). Adapted from graphics gems 2.
 // Inverts upper left by calculating its determinant and multiplying it to the symmetric