Add slang shaders for additional ray tracing samples

shaders/slang/raytracingintersection/raytracingintersection.slang

@@ -0,0 +1,96 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct Payload
+{
+    float3 hitValue;
+}
+
+RaytracingAccelerationStructure accelStruct;
+RWTexture2D<float4> image;
+
+struct UBO
+{
+    float4x4 viewInverse;
+    float4x4 projInverse;
+    float4 lightPos;
+};
+ConstantBuffer<UBO> ubo;
+
+struct Sphere {
+	float3 center;
+	float radius;
+	float4 color;
+};
+StructuredBuffer<Sphere> spheres;
+
+// Ray-sphere intersection
+// By Inigo Quilez, from https://iquilezles.org/articles/spherefunctions/
+float sphIntersect(const Sphere s, float3 ro, float3 rd)
+{
+    float3 oc = ro - s.center;
+    float b = dot(oc, rd);
+    float c = dot(oc, oc) - s.radius * s.radius;
+    float h = b * b - c;
+    if (h < 0.0) {
+        return -1.0;
+    }
+    h = sqrt(h);
+    return -b - h;
+}
+
+[shader("intersection")]
+void intersectionMain() {
+    Sphere sphere = spheres[PrimitiveIndex()];
+    float hit = sphIntersect(sphere, WorldRayOrigin(), WorldRayDirection());
+
+    if (hit > 0) {
+        ReportHit(hit, 0, 0);
+    }
+}
+
+[shader("raygeneration")]
+void raygenerationMain()
+{
+    uint3 LaunchID = DispatchRaysIndex();
+    uint3 LaunchSize = DispatchRaysDimensions();
+
+    const float2 pixelCenter = float2(LaunchID.xy) + float2(0.5, 0.5);
+    const float2 inUV = pixelCenter / float2(LaunchSize.xy);
+    float2 d = inUV * 2.0 - 1.0;
+    float4 target = mul(ubo.projInverse, float4(d.x, d.y, 1, 1));
+
+    RayDesc rayDesc;
+    rayDesc.Origin = mul(ubo.viewInverse, float4(0, 0, 0, 1)).xyz;
+    rayDesc.Direction = mul(ubo.viewInverse, float4(normalize(target.xyz), 0)).xyz;
+    rayDesc.TMin = 0.001;
+    rayDesc.TMax = 10000.0;
+
+    Payload payload;
+    TraceRay(accelStruct, RAY_FLAG_FORCE_OPAQUE, 0xff, 0, 0, 0, rayDesc, payload);
+
+    image[int2(LaunchID.xy)] = float4(payload.hitValue, 0.0);
+}
+
+[shader("closesthit")]
+void closesthitMain(inout Payload payload)
+{
+	Sphere sphere = spheres[PrimitiveIndex()];
+
+    float3 worldPos = WorldRayOrigin() + WorldRayDirection() * RayTCurrent();
+    float3 worldNormal = normalize(worldPos - sphere.center);
+
+    // Basic lighting
+    float3 lightVector = normalize(ubo.lightPos.xyz);
+    float dot_product = max(dot(lightVector, worldNormal), 0.2);
+    payload.hitValue = sphere.color.rgb * dot_product;	
+}
+
+[shader("miss")]
+void missMain(inout Payload payload)
+{
+    payload.hitValue = float3(0.0, 0.0, 0.2);
+}