HLSL: Add gather, improve proto generator machine for upcoming 2DMS/Shadow

Test/hlsl.gather.basic.dx10.frag

@@ -0,0 +1,48 @@
+SamplerState       g_sSamp : register(s0);
+uniform sampler2D          g_sSamp2d;
+
+Texture1D          g_tTex1df4a : register(t1);
+
+uniform Texture1D <float4> g_tTex1df4 : register(t0);
+Texture1D <int4>   g_tTex1di4;
+Texture1D <uint4>  g_tTex1du4;
+
+Texture2D <float4> g_tTex2df4;
+Texture2D <int4>   g_tTex2di4;
+Texture2D <uint4>  g_tTex2du4;
+
+Texture3D <float4> g_tTex3df4;
+Texture3D <int4>   g_tTex3di4;
+Texture3D <uint4>  g_tTex3du4;
+
+TextureCube <float4> g_tTexcdf4;
+TextureCube <int4>   g_tTexcdi4;
+TextureCube <uint4>  g_tTexcdu4;
+
+struct PS_OUTPUT
+{
+    float4 Color : SV_Target0;
+    float  Depth : SV_Depth;
+};
+
+PS_OUTPUT main()
+{
+   PS_OUTPUT psout;
+
+   // no 1D gathers
+
+   float4 txval20 = g_tTex2df4 . Gather(g_sSamp, float2(0.1, 0.2));
+   int4   txval21 = g_tTex2di4 . Gather(g_sSamp, float2(0.3, 0.4));
+   uint4  txval22 = g_tTex2du4 . Gather(g_sSamp, float2(0.5, 0.6));
+
+   // no 3D gathers
+
+   float4 txval40 = g_tTexcdf4 . Gather(g_sSamp, float3(0.1, 0.2, 0.3));
+   int4   txval41 = g_tTexcdi4 . Gather(g_sSamp, float3(0.4, 0.5, 0.6));
+   uint4  txval42 = g_tTexcdu4 . Gather(g_sSamp, float3(0.7, 0.8, 0.9));
+
+   psout.Color = 1.0;
+   psout.Depth = 1.0;
+
+   return psout;
+}