Add slang shaders for gears sample

shaders/slang/gears/gears.slang

@@ -0,0 +1,58 @@
+/* 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 EyePos;
+  float3 LightVec;
+};
+
+struct UBO
+{
+  float4x4 projection;
+  float4x4 view;
+  float4 lightpos;
+  float4x4 model[3];
+};
+ConstantBuffer<UBO> ubo;
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input, uint InstanceIndex: SV_StartInstanceLocation)
+{
+	VSOutput output;
+	output.Normal = normalize(mul((float3x3)transpose(ubo.model[InstanceIndex]), input.Normal).xyz);
+	output.Color = input.Color;
+	float4x4 modelView = mul(ubo.view, ubo.model[InstanceIndex]);
+	float4 pos = mul(modelView, float4(input.Pos, 1.0));
+	output.EyePos = mul(modelView, pos).xyz;
+	float4 lightPos = mul(float4(ubo.lightpos.xyz, 1.0), modelView);
+	output.LightVec = normalize(lightPos.xyz - output.EyePos);
+	output.Pos = mul(ubo.projection, pos);
+	return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+  float3 eye = normalize(-input.EyePos);
+  float3 reflected = normalize(reflect(-input.LightVec, input.Normal));
+
+  float4 ambient = float4(0.2, 0.2, 0.2, 1.0);
+  float4 diffuse = float4(0.5, 0.5, 0.5, 0.5) * max(dot(input.Normal, input.LightVec), 0.0);
+  float4 specular = float4(0.5, 0.5, 0.5, 1.0) * pow(max(dot(reflected, eye), 0.0), 0.8) * 0.25;
+
+  return float4((ambient + diffuse) * float4(input.Color, 1.0) + specular);
+}