Add slang shader for gltf sample

shaders/slang/gltfloading/mesh.slang

@@ -0,0 +1,64 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+	float3 Pos;
+	float3 Normal;
+	float2 UV;
+	float3 Color;
+};
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+	float3 Normal;
+	float3 Color;
+	float2 UV;
+	float3 ViewVec;
+	float3 LightVec;
+};
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 view;
+	float4 lightPos;
+	float4 viewPos;
+};
+ConstantBuffer<UBO> ubo;
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input, uniform float4x4 modelMat)
+{
+	VSOutput output;
+	output.Normal = input.Normal;
+	output.Color = input.Color;
+    output.UV = input.UV;
+    output.Pos = mul(ubo.projection, mul(ubo.view, mul(modelMat, float4(input.Pos.xyz, 1.0))));
+
+    float4 pos = mul(ubo.view, mul(modelMat, float4(input.Pos.xyz, 1.0)));
+	output.Normal = mul((float3x3)ubo.view, input.Normal);
+	output.LightVec = ubo.lightPos.xyz - pos.xyz;
+	output.ViewVec = ubo.viewPos.xyz - pos.xyz;
+	return output;
+}
+
+[[vk::binding(0, 1)]] Sampler2D samplerColorMap;
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+    float4 color = samplerColorMap.Sample(input.UV) * float4(input.Color, 1.0);
+
+    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), 16.0) * float3(0.75, 0.75, 0.75);
+    return float4(diffuse * color.rgb + specular, 1.0);
+}