Added slang shaders for additional samples

shaders/slang/offscreen/phong.slang

@@ -0,0 +1,63 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+    float3 Pos;
+    float3 Color;
+    float3 Normal;
+};
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float ClipDistance : SV_ClipDistance0;
+    float3 Normal;
+    float3 Color;
+    float3 EyePos;
+    float3 LightVec;
+};
+
+struct UBO
+{
+    float4x4 projection;
+    float4x4 view;
+    float4x4 model;
+    float4 lightPos;
+};
+ConstantBuffer<UBO> ubo;
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input)
+{
+    VSOutput output;
+    output.Normal = input.Normal;
+    output.Color = input.Color;
+    output.Pos = mul(ubo.projection, mul(ubo.view, mul(ubo.model, float4(input.Pos, 1.0))));
+    output.EyePos = mul(ubo.view, mul(ubo.model, float4(input.Pos, 1.0))).xyz;
+    output.LightVec = normalize(ubo.lightPos.xyz - output.EyePos);
+    // Clip against reflection plane
+    float4 clipPlane = float4(0.0, 0.0, 0.0, 0.0);
+    output.ClipDistance = dot(float4(input.Pos, 1.0), clipPlane);
+    return output;
+}
+
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+	float3 Eye = normalize(-input.EyePos);
+	float3 Reflected = normalize(reflect(-input.LightVec, input.Normal));
+	float4 IAmbient = float4(0.1, 0.1, 0.1, 1.0);
+	float4 IDiffuse = max(dot(input.Normal, input.LightVec), 0.0).xxxx;
+	float specular = 0.75;
+	float4 ISpecular = float4(0.0, 0.0, 0.0, 0.0);
+	if (dot(input.EyePos, input.Normal) < 0.0)
+	{
+		ISpecular = float4(0.5, 0.5, 0.5, 1.0) * pow(max(dot(Reflected, Eye), 0.0), 16.0) * specular;
+	}
+	return float4((IAmbient + IDiffuse) * float4(input.Color, 1.0) + ISpecular);
+}