Add slang shaders for tessellation samples

shaders/slang/tessellation/passthrough.slang

@@ -0,0 +1,83 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 Normal;
+    float2 UV;
+};
+
+struct HSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 Normal;
+    float2 UV;
+};
+
+struct DSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 Normal;
+    float2 UV;
+};
+
+struct ConstantsHSOutput
+{
+    float TessLevelOuter[3] : SV_TessFactor;
+    float TessLevelInner[2] : SV_InsideTessFactor;
+};
+
+struct UBO
+{
+    float4x4 projection;
+    float4x4 model;
+    float tessAlpha;
+    float tessLevel;
+};
+ConstantBuffer<UBO> ubo;
+
+ConstantsHSOutput ConstantsHS(InputPatch<VSOutput, 3> patch)
+{
+    ConstantsHSOutput output;
+    output.TessLevelInner[0] = 1;
+    output.TessLevelInner[1] = 1;
+    output.TessLevelOuter[0] = 1;
+    output.TessLevelOuter[1] = 1;
+    output.TessLevelOuter[2] = 1;
+    return output;
+}
+
+[shader("hull")]
+[domain("tri")]
+[partitioning("integer")]
+[outputtopology("triangle_cw")]
+[outputcontrolpoints(3)]
+[patchconstantfunc("ConstantsHS")]
+[maxtessfactor(20.0f)]
+HSOutput hullMain(InputPatch<VSOutput, 3> patch, uint InvocationID : SV_OutputControlPointID)
+{
+    HSOutput output;
+    output.Pos = patch[InvocationID].Pos;
+	output.Normal = patch[InvocationID].Normal;
+	output.UV = patch[InvocationID].UV;
+    return output;
+}
+
+[shader("domain")]
+[domain("tri")]
+DSOutput domainMain(ConstantsHSOutput input, float3 TessCoord: SV_DomainLocation, const OutputPatch<HSOutput, 3> patch)
+{
+    DSOutput output = (DSOutput)0;
+    output.Pos = (TessCoord.x * patch[0].Pos) +
+                 (TessCoord.y * patch[1].Pos) +
+                 (TessCoord.z * patch[2].Pos);
+    output.Pos = mul(ubo.projection, mul(ubo.model, output.Pos));
+
+    output.Normal = TessCoord.x * patch[0].Normal + TessCoord.y * patch[1].Normal + TessCoord.z * patch[2].Normal;
+    output.UV = TessCoord.x * patch[0].UV + TessCoord.y * patch[1].UV + TessCoord.z * patch[2].UV;
+    return output;
+}