Added slang shaders for additional samples

shaders/slang/multithreading/phong.slang

@@ -0,0 +1,54 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+    float3 Pos;
+    float3 Normal;
+    float3 Color;
+};
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 Normal;
+    float3 Color;
+    float3 ViewVec;
+    float3 LightVec;
+};
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input, uniform float4x4 mvp, uniform float3 color)
+{
+    VSOutput output;
+    if ((input.Color.r == 1.0) && (input.Color.g == 0.0) && (input.Color.b == 0.0))
+    {
+        output.Color = color;
+    }
+    else
+    {
+        output.Color = input.Color;
+    }
+    output.Pos = mul(mvp, float4(input.Pos.xyz, 1.0));
+    float4 pos = mul(mvp, float4(input.Pos, 1.0));
+    output.Normal = mul((float3x3)mvp, input.Normal);
+    float3 lPos = float3(0.0, 0.0, 0.0);
+    output.LightVec = lPos - pos.xyz;
+    output.ViewVec = -pos.xyz;
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+	float3 N = normalize(input.Normal);
+	float3 L = normalize(input.LightVec);
+	float3 V = normalize(input.ViewVec);
+	float3 R = reflect(-L, N);
+	float3 diffuse = max(dot(N, L), 0.0) * input.Color;
+	float3 specular = pow(max(dot(R, V), 0.0), 8.0) * float3(0.75, 0.75, 0.75);
+	return float4(diffuse + specular, 1.0);
+}