Added HLSL shaders

shaders/hlsl/raytracingpositionfetch/closesthit.rchit

@@ -0,0 +1,57 @@
+/* Copyright (c) 2024, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct Attributes
+{
+    float2 bary;
+};
+
+struct Payload
+{
+    [[vk::location(0)]] float3 hitValue;
+};
+
+struct UBO
+{
+    float4x4 viewInverse;
+    float4x4 projInverse;
+    float4 lightPos;
+};
+cbuffer ubo : register(b2)
+{
+    UBO ubo;
+};
+
+[[vk::ext_extension("SPV_KHR_ray_tracing_position_fetch")]]
+
+[shader("closesthit")]
+void main(inout Payload p, in Attributes attribs)
+{
+	// We need the barycentric coordinates to calculate data for the current position
+    const float3 barycentricCoords = float3(1.0f - attribs.bary.x - attribs.bary.y, attribs.bary.x, attribs.bary.y);
+
+	// With VK_KHR_ray_tracing_position_fetch we can access the vertices for the hit triangle in the shader
+
+    // We need to use special syntax for SPIR-V inlines
+    #define HitTriangleVertexPositionsKHR 5391
+    [[vk::ext_builtin_output(HitTriangleVertexPositionsKHR)]]
+    static float3 gl_HitTriangleVertexPositions[3];
+
+    float3 vertexPos0 = gl_HitTriangleVertexPositions[0];
+    float3 vertexPos1 = gl_HitTriangleVertexPositions[1];
+    float3 vertexPos2 = gl_HitTriangleVertexPositions[2];
+    float3 currentPos = vertexPos0 * barycentricCoords.x + vertexPos1 * barycentricCoords.y + vertexPos2 * barycentricCoords.z;
+
+	// Calcualte the normal from above values
+    float3 normal = normalize(cross(vertexPos1 - vertexPos0, vertexPos2 - vertexPos0));
+    normal = normalize(mul(float4(normal, 1.0), WorldToObject4x3()));
+
+	// Basic lighting
+    float3 lightDir = normalize(ubo.lightPos.xyz - currentPos);
+    float diffuse = max(dot(normal, lightDir), 0.0);
+
+    p.hitValue.rgb = 0.1 + diffuse;
+}