Rework compute kernel

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "cmake.generator": "Ninja"
+}

CMakeLists.txt

@@ -17,6 +17,7 @@ find_package(glfw3 CONFIG REQUIRED)
 find_package(glm CONFIG REQUIRED)
 find_package(Ktx CONFIG REQUIRED)
 find_package(imgui CONFIG REQUIRED)
+find_package(slang CONFIG REQUIRED)
 
 add_executable(RayTracer "")
 target_include_directories(RayTracer PUBLIC src/)
@@ -26,12 +27,11 @@ target_link_libraries(RayTracer PUBLIC imgui::imgui)
 target_link_libraries(RayTracer PUBLIC GLEW::GLEW)
 target_link_libraries(RayTracer PUBLIC glm::glm)
 target_link_libraries(RayTracer PUBLIC KTX::ktx)
-if(WIN32)
+target_link_libraries(RayTracer PUBLIC slang::slang)
-target_include_directories(RayTracer PUBLIC ${VCPKG_INSTALLED_DIR}/x64-windows/include)
+
-target_link_libraries(RayTracer PUBLIC ${VCPKG_INSTALLED_DIR}/x64-windows/lib/slang.lib)
+if(APPLE)
-elseif(APPLE)
     target_include_directories(RayTracer PUBLIC ${VCPKG_INSTALLED_DIR}/arm64-osx/include)
-SET(CMAKE_OSX_DEPLOYMENT_TARGET 26.0)
+    set(CMAKE_OSX_DEPLOYMENT_TARGET 26.0)
     target_link_libraries(RayTracer PUBLIC
       "-framework Metal"
       "-framework MetalKit"
@@ -39,6 +39,17 @@ target_link_libraries(RayTracer PUBLIC
       "-framework Foundation"
       "-framework QuartzCore"
     )
-
 endif()
+
+if(WIN32)
+    target_include_directories(RayTracer PUBLIC ${VCPKG_INSTALLED_DIR}/x64-windows/include)
+    target_link_libraries(RayTracer PUBLIC ${VCPKG_INSTALLED_DIR}/x64-windows/lib/slang.lib)
+endif()
+
+add_custom_command(TARGET RayTracer POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy_directory
+        ${CMAKE_CURRENT_SOURCE_DIR}/res
+        $<TARGET_FILE_DIR:RayTracer>
+)
+
 add_subdirectory(src/)

res/shaders/ClosestHit.slang

@@ -1,125 +0,0 @@
-import Common;
-
-
-[shader("closesthit")]
-void closestHit(inout RayPayload hitValue, in BuiltInTriangleIntersectionAttributes attr)
-{
-    hitValue.hit = true;
-    // todo: replace with anyhit shader
-    if(hitValue.anyHit)
-        return;
-    const float3 barycentricCoords = float3(1.0f - attr.barycentrics.x - attr.barycentrics.y, attr.barycentrics.x, attr.barycentrics.y);
-
-    ModelReference m = pParams.modelData[InstanceID()];
-
-    // offset into the index buffer
-    uint indexOffset = m.indicesOffset;
-    // added to indices to reference correct part of global mesh pool
-    uint vertexOffset = m.positionOffset;
-
-    uint vertexIndex0 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * PrimitiveIndex() + 0];
-    uint vertexIndex1 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * PrimitiveIndex() + 1];
-    uint vertexIndex2 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * PrimitiveIndex() + 2];
-
-    Vertex attr0 = loadVertex(vertexIndex0);
-    Vertex attr1 = loadVertex(vertexIndex1);
-    Vertex attr2 = loadVertex(vertexIndex2);
-
-    Vertex vert = Vertex.interpolate(attr0, attr1, attr2, barycentricCoords);
-
-    float3 normalLight = dot(vert.normal, WorldRayDirection()) < 0 ? vert.normal : -vert.normal;
-
-    MaterialParameter mat = pParams.materialData[m.materialIndex];
-    float3 emissive = mat.emissive_type.xyz;
-
-    float3 localAccRad = float3(0);
-    float3 rnd = rand01(uint3(vertexIndex0, vertexIndex1, vertexIndex2));
-    //float kt = ka + ks;
-    //float s = -log(rnd.z) / kt;
-    //float3 xs = r.o + s * r.d;
-    //if (s < t) {
-    //    float p = kt * rnd.z;
-    //    if (depth > 5) {
-    //        if (rnd.z >= p) break;
-    //        else accmat /= p;
-    //    }
-    //    float3 ldirect = nextEventEstimation(accmat, r.d, xs, -r.d, kt, true, rnd);
-    //    accrad += (fogEmm + ks * ldirect) / kt;
-    //    accmat *= ks / kt;
-    //    rayDesc.Origin = xs;
-    //    rayDesc.Direction = float3(
-    //        cos(2*PI*rnd.x)*sqrt(1-rnd.y*rnd.y),
-    //        sin(2*PI*rnd.x)*sqrt(1-rnd.y*rnd.y),
-    //        rnd.y
-    //    );
-    //    continue;
-    //}
-
-    //float p = max(max(mat.albedo.x, mat.albedo.y), mat.albedo.z);
-    //if(hitValue.depth > 5) {
-    //    if (rnd.z >= p) return;
-    //    else hitValue.accmat /= p;
-    //}
-
-
-    //-- Ideal DIFFUSE reflection
-    //if(bool(useNEE)) {
-    //    accrad += nextEventEstimation(accmat, r.d, params.x, params.nl, kt, false, rnd);
-    //}
-    for(uint i = 0; i < pSamps.numDirectionalLights; ++i) {
-        float3 x = vert.position;
-        float3 l = -pParams.directionalLights[i].direction.xyz;
-        RayDesc rayDesc;
-        rayDesc.TMax = 10000.0f;
-        rayDesc.TMin = 0.001f;
-        rayDesc.Origin = x;
-        rayDesc.Direction = l;
-        RayPayload payload;
-        payload.depth = hitValue.depth;
-        payload.emissive = 1;
-        payload.anyHit = true;
-        TraceRay(pParams.scene, 0, 0xff, 0, 0, 0, rayDesc, payload);
-
-        // we have missed all geometry, so directional light is affecting us
-        if(!payload.hit) {
-            localAccRad += mat.shade(vert.normal, -WorldRayDirection(), -pParams.directionalLights[i].direction, pParams.directionalLights[i].color);
-        }
-    }
-    for(uint i = 0; i < pSamps.numPointLights; ++i) {
-        RayPayload payload;
-        float3 x = vert.position;
-        float3 l = pParams.pointLights[i].position - vert.position;
-        // todo: cancel if light too far away to affect
-
-        RayDesc rayDesc;
-        rayDesc.TMax = 1.0f;
-        rayDesc.TMin = 0.001f;
-        rayDesc.Origin = x;
-        rayDesc.Direction = l;
-        TraceRay(pParams.scene, 0, 0xff, 0, 0, 0, rayDesc, payload);
-    
-        // hitting only after the light
-        if(!payload.hit) {
-            localAccRad += mat.shade(vert.normal, -WorldRayDirection(), normalize(l), pParams.pointLights[i].color);
-        }
-    }
-    hitValue.light += localAccRad + emissive;
-    // Indirect Illumination: cosine-weighted importance sampling
-    if(hitValue.depth < 12) {
-    	float r1 = 2 * PI * rnd.x, r2 = rnd.y, r2s = sqrt(r2);
-        float3 w = normalLight;
-        float3 u = normalize((cross(abs(w.x)>0.1 ? float3(0,1,0) : float3(1,0,0), w)));
-        float3 v = cross(w,u);
-        RayDesc rayDesc;
-        rayDesc.TMax = 10000.0f;
-        rayDesc.TMin = 0.001f;
-        rayDesc.Origin = vert.position;
-        rayDesc.Direction = normalize(u*cos(r1)*r2s + v * sin(r1)*r2s + w * sqrt(1 - r2));
-        RayPayload payload;
-        payload.light = float3(0);
-        payload.emissive = 0;   // in the next bounce, consider reflective part only!
-        payload.depth = hitValue.depth+1;
-        payload.anyHit = false;
-        TraceRay(pParams.scene, 0, 0xff, 0, 0, 0, rayDesc, payload);
-    }
-}

res/shaders/ComputeKernel.slang

@@ -1,21 +1,55 @@
 import Common;
 
+struct HitInfo
+{
+  float3 position;
+  float3 normal;
+  float3 barycentricCoords;
+  uint instanceIndex;
+  uint primitiveIndex;
+};
+
+HitInfo get_hit_info(RayQuery<RAY_FLAG_NONE> q)
+{
+  HitInfo info;
+  // In Slang for Metal/Vulkan, these are the standard names for ray query results
+  info.instanceIndex = q.CommittedInstanceID();
+  info.primitiveIndex = q.CommittedPrimitiveIndex();
+  float2 baryCenter = q.CommittedRayBarycentrics();
+  info.barycentricCoords = float3(1.0f - baryCenter.x - baryCenter.y, baryCenter.x, baryCenter.y);
+  return info;
+}
+
+Vertex interpolate_vertex(uint vertexIdx0, uint vertexIdx1, uint vertexIdx2, float3 bary)
+{
+  Vertex v0 = loadVertex(vertexIdx0);
+  Vertex v1 = loadVertex(vertexIdx1);
+  Vertex v2 = loadVertex(vertexIdx2);
+
+  Vertex vert;
+  vert.position = v0.position * bary.x + v1.position * bary.y + v2.position * bary.z;
+  vert.texCoords = v0.texCoords * bary.x + v1.texCoords * bary.y + v2.texCoords * bary.z;
+  vert.normal = v0.normal * bary.x + v1.normal * bary.y + v2.normal * bary.z;
+  return vert;
+}
+
 [shader("compute")]
 [numthreads(8, 8, 1)]
-void computeKernel(uint2 threadId [[thread_position_in_grid]])
+void computeKernel(uint2 threadId: SV_DispatchThreadID)
 {
   if (threadId.x >= pParams.cam.width || threadId.y >= pParams.cam.height)
     return;
 
   uint pass = pSamps.pass;
   uint samplesPerPixel = pSamps.samplesPerPixel;
-    if (pass == samplesPerPixel) return;
+  if (pass == samplesPerPixel)
+    return;
 
   uint2 pix = threadId;
   uint imgWidth = pParams.cam.width;
   uint imgHeight = pParams.cam.height;
 
-    //-- define cam
+  // -- Camera setup --
   float3 camPos = pParams.cam.cameraPosition;
   float3 camForward = pParams.cam.cameraForward;
   float f = pParams.cam.f;
@@ -32,50 +66,120 @@ void computeKernel(uint2 threadId [[thread_position_in_grid]])
 
   float S_I = (S_O * f) / (S_O - f);
 
-    //-- sample sensor
+  // -- Sample sensor --
   float3 rnd = rand01(uint3(pix, pass));
   float2 rnd2 = 2.0f * float2(rnd.xy); // tent filter
-    float2 tent = float2(rnd2.x < 1 ? sqrt(rnd2.x) - 1 : 1 - sqrt(2 - rnd2.x), 
+  float2 tent = float2(rnd2.x < 1 ? sqrt(rnd2.x) - 1 : 1 - sqrt(2 - rnd2.x), rnd2.y < 1 ? sqrt(rnd2.y) - 1 : 1 - sqrt(2 - rnd2.y));
-                         rnd2.y < 1 ? sqrt(rnd2.y) - 1 : 1 - sqrt(2 - rnd2.y));
   float2 s = ((float2(pix) + 0.5f * (0.5f + float2((pass / 2) % 2, pass % 2) + tent)) / float2(imgWidth, imgHeight) - 0.5f) * sdim;
 
   float3 lc = camPos + camForward * 0.035f; // sample on 3d sensor plane
   float3 spos = camPos + cx * s.x + cy * s.y;
   float3 rayDir = normalize(lc - spos);
 
-    //-- setup lens (simplified)
+  // -- Lens (Aperture) --
-    float3 lensSample = lc; // for now, just use camera position slightly offset if needed? 
-    // Actually let's do it properly based on A parameter
   float3 lensN = -camForward;
   float3 lensX = cross(lensN, float3(0, 1, 0));
   float3 lensY = cross(lensN, lensX);
-    float2 rnd01 = rand01(uint3(pix, pass)).xy;
+  float2 rndL = rand01(uint3(pix, pass + 100)).xy;
-    lensSample = lc + rnd01.x * A * lensX + rnd01.y * A * lensY;
+  float3 lensSample = lc + (rndL.x - 0.5) * A * lensX + (rndL.y - 0.5) * A * lensY;
 
-    float focalPoint = camPos + (S_O + S_I) * camForward;
+  float3 focalPoint = camPos + (S_O + S_I) * camForward;
-    float t_focus = dot(focalPoint - lensSample, lensN) / dot(rayDir, lensN);
-    float3 focus = lensSample + t_focus * rayDir;
 
+  // Simple ray construction
   float3 rayOrg = lensSample;
-    float3 rayDirFinal = normalize(focus - lensSample);
+  float3 rayDirFinal = normalize(focalPoint - lensSample);
 
-    // Ray Tracing Loop
+  // -- Path Tracing Loop --
-    RayPayload payload;
+  float3 accumulatedRadiance = float3(0.0);
-    payload.light = float3(0);
+  float3 throughput = float3(1.0);
-    payload.emissive = 1.0f;
-    payload.depth = 1;
-    payload.hit = false;
-    payload.anyHit = false;
 
-    // Note: We are using the compute-based intersection loop because it's easier to implement in a single kernel
+  for (int bounce = 0; bounce < 4; ++bounce)
-    // and we have access to common helper functions. In a full RT pipeline we would use dedicated shaders.
+  {
+    RayQuery<RAY_FLAG_NONE> q;
+    RayDesc rayDesc;
+    rayDesc.Origin = rayOrg;
+    rayDesc.Direction = rayDirFinal;
+    rayDesc.TMin = 0.001;
+    rayDesc.TMax = 1e20;
+    q.TraceRayInline(pParams.scene, RAY_FLAG_NONE, 0xff, rayDesc);
 
-    // Since we don't have the specialized 'intersector' object from before, 
+    if (q.Proceed())
-    // we will use a placeholder for now or assume it's available if provided by Slang/Metal context.
+    {
-    // BUT since I am writing this from scratch, I should probably implement the traversal OR 
+      HitInfo hit = get_hit_info(q);
-    // just use MS's Compute-based approach as in Compute.metal which worked.
 
-    // Wait! To keep it simple and "lazy", I will just copy the logic from Compute.metal into this Slang file
+      ModelReference m = pParams.modelData[hit.instanceIndex];
-    // and replace all its types with pParams fields.
+      uint indexOffset = m.indicesOffset;
+      uint vertexOffset = m.positionOffset;
 
+      uint v0 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * hit.primitiveIndex + 0];
+      uint v1 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * hit.primitiveIndex + 1];
+      uint v2 = vertexOffset + pParams.indexBuffer[indexOffset + 3 * hit.primitiveIndex + 2];
+
+      Vertex vert = interpolate_vertex(v0, v1, v2, hit.barycentricCoords);
+      MaterialParameter mat = pParams.materialData[m.materialIndex];
+
+      accumulatedRadiance += throughput * mat.emissive_type.xyz;
+
+      // --- Direct Lighting (NEE) ---
+      float3 directLight = float3(0);
+      for (uint i = 0; i < pSamps.numDirectionalLights; ++i)
+      {
+        float3 lDir = -pParams.directionalLights[i].direction.xyz;
+        RayQuery<RAY_FLAG_NONE> sq;
+        RayDesc rayDesc;
+        rayDesc.Origin = vert.position + vert.normal * 0.001;
+        rayDesc.Direction = lDir;
+        rayDesc.TMin = 0.001;
+        rayDesc.TMax = 1e20;
+        sq.TraceRayInline(pParams.scene, RAY_FLAG_NONE, 0xff, rayDesc);
+        if (!sq.Proceed())
+        {
+          directLight += mat.shade(vert.normal, -rayDirFinal, lDir, pParams.directionalLights[i].color);
+        }
+      }
+      for (uint i = 0; i < pSamps.numPointLights; ++i)
+      {
+        float3 lVec = pParams.pointLights[i].position - vert.position;
+        float3 lDir = normalize(lVec);
+        RayQuery<RAY_FLAG_NONE> sq;
+        RayDesc rayDesc;
+        rayDesc.Origin = vert.position + vert.normal * 0.001;
+        rayDesc.Direction = lDir;
+        rayDesc.TMin = 0.001;
+        rayDesc.TMax = 1e20;
+        sq.TraceRayInline(pParams.scene, RAY_FLAG_NONE, 0xff, rayDesc);
+        if (sq.Proceed() == false || sq.CommittedRayT() > length(lVec))
+        {
+          directLight += mat.shade(vert.normal, -rayDirFinal, lDir, pParams.pointLights[i].color);
+        }
+      }
+      accumulatedRadiance += throughput * directLight;
+
+      // --- Indirect Lighting (Cosine-weighted sampling) ---
+      float3 rnd = rand01(uint3(pix, pass + bounce + 200));
+      float r1 = 2.0 * PI * rnd.x;
+      float r2 = rnd.y;
+      float r2s = sqrt(r2);
+
+      float3 w = vert.normal;
+      float3 u = normalize(cross(abs(w.x) > 0.1 ? float3(0, 1, 0) : float3(1, 0, 0), w));
+      float3 v = cross(w, u);
+      float3 nextDir = normalize(u * cos(r1) * r2s + v * sin(r1) * r2s + w * sqrt(1.0 - r2));
+
+      throughput *= mat.albedo_alpha.xyz;
+
+      rayOrg = vert.position + vert.normal * 0.001;
+      rayDirFinal = nextDir;
+
+      if (length(throughput) < 0.01)
+        break;
+    }
+    else
+    {
+      accumulatedRadiance += throughput * float3(0.05, 0.05, 0.1);
+      break;
+    }
+  }
+
+  pParams.image[threadId] = float4(accumulatedRadiance, 1.0);
 }

res/shaders/Miss.slang

@@ -1,8 +0,0 @@
-import Common;
-
-[shader("miss")]
-void miss(inout RayPayload p)
-{
-    p.light = float3(0.05, 0.05, 0.1); // Dark blueish background instead of black
-    p.hit = false;
-}

res/shaders/RayGen.slang

@@ -1,57 +0,0 @@
-import Common;
-
-[shader("raygeneration")]
-void raygen()
-{
-    if(pSamps.pass == pSamps.samplesPerPixel) return;
-    uint2 pix = DispatchRaysIndex().xy;
-    uint2 imgdim = DispatchRaysDimensions().xy;
-
-    //-- define cam
-    Ray cam = Ray(pParams.cam.cameraPosition, pParams.cam.cameraForward);
-    float3 cx = -normalize(cross(cam.d, abs(cam.d.y) < 0.9 ? float3(0, 1, 0) : float3(0, 0, 1))), cy = cross(cam.d, cx);
-    const float2 sdim = float2(0.036, 0.024);
-
-    float S_I = (pParams.cam.S_O * pParams.cam.f) / (pParams.cam.S_O - pParams.cam.f);
-
-    //-- sample sensor
-    float2 rnd2 = 2*rand01(uint3(pix, pSamps.pass)).xy;   // vvv tent filter sample  
-    float2 tent = float2(rnd2.x<1 ? sqrt(rnd2.x)-1 : 1-sqrt(2-rnd2.x), rnd2.y<1 ? sqrt(rnd2.y)-1 : 1-sqrt(2-rnd2.y));
-    float2 s = ((pix + 0.5 * (0.5 + float2((pSamps.pass/2)%2, pSamps.pass%2) + tent)) / float2(imgdim) - 0.5) * sdim;
-    float3 spos = cam.o + cx*s.x + cy*s.y, lc = cam.o + cam.d * 0.035;           // sample on 3d sensor plane
-    Ray r = Ray(lc, normalize(lc - spos));      // construct ray
-
-
-    //-- setup lens
-    float3 lensP = lc;
-    float3 lensN = -cam.d;
-    float3 lensX = cross(lensN, float3(0, 1, 0)); // the exact vector doesnt matter
-    float3 lensY = cross(lensN, lensX);
-    uint3 rndSeed = uint3(pix, pSamps.pass);
-    float2 rnd01 = rand01(rndSeed).xy;
-
-    float3 lensSample = lensP + rnd01.x * pParams.cam.A * lensX + rnd01.y * pParams.cam.A * lensY;
-
-    float3 focalPoint = cam.o + (pParams.cam.S_O + S_I) * cam.d;
-    float t = dot(focalPoint - r.o, lensN) / dot(r.d, lensN);
-    float3 focus = r.o + t * r.d;
-
-    RayDesc rayDesc;
-    rayDesc.Origin = lensSample;
-    rayDesc.Direction = normalize(focus - lensSample);
-    rayDesc.TMin = 0.001;
-    rayDesc.TMax = 10000.0;
-	
-    const uint maxDepth = 12;
-    RayPayload payload;
-    // initialize accumulated radiance and bxdf
-    payload.light=float3(0);
-    payload.emissive = 1;
-    payload.depth = 1;
-    payload.anyHit = false;
-    TraceRay(pParams.scene, 0, 0xff, 0, 0, 0, rayDesc, payload);
-
-    if(pSamps.pass == 0) pParams.radianceAccumulator[pix] = float4(0);
-    pParams.radianceAccumulator[pix] += float4(payload.light / pSamps.samplesPerPixel, 0);
-    pParams.image[pix] = float4(clamp(pParams.radianceAccumulator[pix].xyz, 0, 1), 1);
-}

src/main.cpp

@@ -12,12 +12,12 @@ int main()
       .color = glm::vec3(1, 1, 1),
   });
   renderer->addPointLight(PointLight{});
-  renderer->addModels(ModelLoader::loadModel("../res/models/cube.fbx"),
+  renderer->addModels(ModelLoader::loadModel("../res/models/stanford-bunny.obj"),
                       glm::mat4(glm::vec4(1.0f, 0.0f, 0.0f, 0.0f), glm::vec4(0.0f, 1.0f, 0.0f, 0.0f), glm::vec4(0.0f, 0.0f, 1.0f, 0.0f),
                                 glm::vec4(0.0f, 0.0f, 0.0f, 1.0f)));
   renderer->generate();
   Camera camera = Camera{
-      .position = glm::vec3(5, 1, 2),
+      .position = glm::vec3(2, 1, 2),
       .target = glm::vec3(0, 0, 0),
       .f = 0,
       .A = 0,

src/metal/CMakeLists.txt

@@ -4,4 +4,5 @@ target_sources(RayTracer
         MetalRenderer.mm
         MetalScene.h
         MetalScene.mm
-        Compute.metal)
+        ComputeKernel.metal
+)

src/metal/Compute.metal

@@ -1,323 +0,0 @@
-#include <metal_stdlib>
-#include <simd/simd.h>
-#include <metal_numeric>
-
-using namespace metal;
-
-using namespace raytracing;
-
-
-enum class MaterialType
-{
-  BlinnPhong
-};
-
-struct GPUCamera
-{
-    packed_float3 position;
-    float f;
-    packed_float3 forward;
-    float S_O;
-    packed_float3 fogEmm;
-    float ks;
-    float A;
-    float ka;
-    float2 sensorSize;
-    uint width;
-    uint height;
-};
-
-struct SampleParams
-{
-    uint pass;
-    uint samplesPerPixel;
-    uint numDirectionalLights;
-    uint numPointLights;
-};
-
-struct Payload
-{
-  float3 rnd01;
-  float3 accumulatedRadiance = float3(0);
-  float3 accumulatedMaterial = float3(1);
-  uint depth = 0;
-  float emissive = 1;
-};
-
-struct ModelReference
-{
-  uint positionOffset = 0;
-  uint numPositions = 0;
-  uint indicesOffset = 0;
-  uint numIndices = 0;
-};
-
-struct HitInfo
-{
-  float t = numeric_limits<float>::max();
-  float3 position;
-  float3 normal;
-  // not entirely sure what that does
-  // its the normal being flipped based on some dot product
-  float3 normalLight;
-  float2 texCoords;
-};
-
-struct BRDF
-{
-  float3 albedo = float3(1, 1, 1);
-  float alpha = 1;
-  float3 specularColor = float3(1, 1, 1);
-  float shininess = 0.004;
-  float3 emissive = float3(0, 0, 0);
-  MaterialType materialType;
-  float3 evaluate(HitInfo hit, float3 viewDir, float3 lightDir, float3 lightColor)
-  {
-    float3 normal = hit.normal;
-    float diffuse = max(dot(normal, lightDir), 0.0f);
-    float3 h = normalize(lightDir + viewDir);
-    float specular = pow(clamp(dot(normal, h), 0.0f, 1.0f), shininess);
-    
-    return (albedo * diffuse * lightColor) + float3(0.03, 0.03, 0.03);
-  }
-};
-
-
-struct PointLight
-{
-  float3 position = float3(0, 0, 0);
-  packed_float3 color = float3(1, 1, 1);
-  float attenuation = 1;
-};
-
-struct DirectionalLight
-{
-  float3 direction = float3(0, 1, 0);
-  float3 color = float3(1, 1, 1);
-  };
-
-float3 rand01(uint3 x)
-{ // pseudo-random number generator
-  for (int i = 3; i-- > 0;)
-    x = ((x >> 8U) ^ uint3(x.y, x.z, x.x)) * 1103515245U;
-  return float3(x) * (1.0f / float(0xffffffffU));
-}
-
-template<typename T, typename IndexType>
-inline T interpolateVertexAttribute(constant T *attributes,
-                                    uint offset,
-                                    IndexType i0,
-                                    IndexType i1,
-                                    IndexType i2,
-                                    float2 uv) {
-    // Look up value for each vertex.
-    const T T0 = attributes[offset + i0];
-    const T T1 = attributes[offset + i1];
-    const T T2 = attributes[offset + i2];
-
-    // Compute the sum of the vertex attributes weighted by the barycentric coordinates.
-    // The barycentric coordinates sum to one.
-    return (1.0f - uv.x - uv.y) * T2 + uv.x * T0 + uv.y * T1;
-}
-
-kernel void computeKernel(
-    uint2 threadId [[thread_position_in_grid]],
-    constant GPUCamera& camera,
-    constant SampleParams& sample,
-    constant packed_uint3* indexBuffer [[buffer(0)]],
-    constant packed_float3* positions [[buffer(1)]],
-    constant packed_float2* texCoords [[buffer(2)]],
-    constant packed_float3* normals [[buffer(3)]],
-    constant ModelReference* modelRefs [[buffer(4)]],
-    constant BRDF* materials [[buffer(5)]],
-    constant DirectionalLight* directionalLights [[buffer(6)]],
-    constant PointLight* pointLights [[buffer(7)]],
-    constant MTLAccelerationStructureInstanceDescriptor* instances [[buffer(8)]],
-    instance_acceleration_structure accelerationStructure [[buffer(9)]],
-    texture2d<float, access::read_write> accumulator [[texture(0)]],
-    texture2d<float, access::read_write> image [[texture(1)]]
-)
-{
-    Payload payload;
-    ray cam;
-    cam.origin = camera.position;
-    cam.direction = normalize(camera.forward);
-    cam.max_distance = INFINITY;
-    float3 cx =
-    normalize(cross(cam.direction, abs(cam.direction.y) < 0.9 ? float3(0, 1, 0) : float3(0, 0, 1))),
-    cy = cross(cx, cam.direction);
-    const float2 sdim = camera.sensorSize; // sensor size (36 x 24 mm)
-    
-    float S_I = (camera.S_O * camera.f) / (camera.S_O - camera.f);
-    
-    //-- sample sensor
-    uint2 pix = threadId;
-    if(pix.x >= camera.width || pix.y >= camera.height)
-        return;
-    
-    payload.rnd01 = rand01(uint3(pix, sample.pass));
-    float2 rnd2 = 2.0f * float2(payload.rnd01.xy); // vvv tent filter sample
-    float2 tent =
-    float2(rnd2.x < 1 ? sqrt(rnd2.x) - 1 : 1 - sqrt(2 - rnd2.x), rnd2.y < 1 ? sqrt(rnd2.y) - 1 : 1 - sqrt(2 - rnd2.y));
-    float2 s =
-    ((float2(pix) + 0.5f * (0.5f + float2((sample.pass / 2) % 2, sample.pass % 2) + tent)) / float2(camera.width, camera.height) -
-     0.5f) *
-    sdim;
-    float3 spos = cam.origin + cx * s.x + cy * s.y, lc = cam.origin + cam.direction * 0.035f; // sample on 3d sensor plane
-    cam.origin = lc;
-    cam.direction = normalize(lc - spos);                                                     // construct ray
-    
-    //-- setup lens
-    float3 lensP = lc;
-    float3 lensN = -cam.direction;
-    float3 lensX = cross(lensN, float3(0, 1, 0)); // the exact vector doesnt matter
-    float3 lensY = cross(lensN, lensX);
-    
-    float3 lensSample = lensP + payload.rnd01.x * camera.A * lensX + payload.rnd01.y * camera.A * lensY;
-    
-    float3 focalPoint = cam.origin + (camera.S_O + S_I) * cam.direction;
-    float t = dot(focalPoint - cam.origin, lensN) / dot(cam.direction, lensN);
-    float3 focus = cam.origin + t * cam.direction;
-    cam.origin = lensSample;
-    cam.direction = normalize(focus - lensSample); // TODO: Fix lens
-    
-    intersector<triangle_data, instancing> i;
-    i.assume_geometry_type(geometry_type::triangle);
-    i.force_opacity(forced_opacity::opaque);
-    
-    typename intersector<triangle_data, instancing>::result_type intersection;
-    while(payload.depth < 12) {
-        i.accept_any_intersection(false);
-        
-        intersection = i.intersect(cam, accelerationStructure, 0xff);
-        
-        if(intersection.type == intersection_type::none)
-            break;
-        
-        uint instanceId = intersection.instance_id;
-        constant ModelReference& ref = modelRefs[instanceId];
-        
-        HitInfo info;
-        info.t = intersection.distance;
-        const auto indices = indexBuffer[ref.indicesOffset + intersection.primitive_id];
-        info.position = interpolateVertexAttribute(positions, ref.positionOffset, indices.x, indices.y, indices.z, intersection.triangle_barycentric_coord);
-        info.texCoords = interpolateVertexAttribute(texCoords, ref.positionOffset, indices.x, indices.y, indices.z, intersection.triangle_barycentric_coord);
-        info.normal = normalize(interpolateVertexAttribute(normals, ref.positionOffset, indices.x, indices.y, indices.z, intersection.triangle_barycentric_coord));
-        info.normalLight = dot(info.normal, cam.direction) < 0 ? info.normal : -info.normal;
-        
-        BRDF brdf;
-      brdf.albedo = float3(0, 1, 0);
-        
-        float p = max(max(brdf.albedo.x, brdf.albedo.y), brdf.albedo.z);
-        if (payload.depth > 5)
-        {
-            if (payload.rnd01.z >= p)
-                break;
-            else
-                payload.accumulatedMaterial /= p;
-        }
-        // emissive
-        payload.accumulatedRadiance += payload.accumulatedMaterial * brdf.emissive * payload.emissive;
-        payload.accumulatedMaterial *= brdf.albedo;
-        
-        // direct lighting
-        for (uint l = 0; l < sample.numDirectionalLights; ++l)
-        {
-            // if there is an intersection, the light is occluded so no lighting
-            ray shadowRay;
-            shadowRay.origin = info.position + info.normal * 1e-3f;
-            shadowRay.direction = -directionalLights[l].direction;
-            shadowRay.max_distance = INFINITY;
-            i.accept_any_intersection(true);
-            intersection = i.intersect(shadowRay, accelerationStructure, 0xff);
-            if(intersection.type == intersection_type::none)
-            {
-                payload.accumulatedRadiance += brdf.evaluate(info, -cam.direction, normalize(shadowRay.direction), directionalLights[l].color);
-            }
-        }
-        for (uint l = 0; l < sample.numPointLights; ++l)
-        {
-            float3 lightDir = pointLights[l].position - info.position;
-            ray shadowRay;
-            shadowRay.origin = info.position + info.normal * 1e-3f;
-            shadowRay.direction = lightDir;
-            shadowRay.max_distance = 1;
-            i.accept_any_intersection(true);
-            intersection = i.intersect(shadowRay, accelerationStructure, 0xff);
-            if (intersection.type == intersection_type::none)
-            {
-                float d = length(lightDir);
-                float illuminance = max(1 - d / pointLights[l].attenuation, 0.0f);
-                
-                payload.accumulatedRadiance += illuminance * brdf.evaluate(info, -cam.direction, normalize(lightDir), pointLights[l].color);
-            }
-        }
-        
-        // TODO: Next Event Estimation for mesh lights
-        
-        // indirect lighting
-        float r1 = 2 * M_PI_F * payload.rnd01.x;
-        float r2 = payload.rnd01.y;
-        float r2s = sqrt(r2);
-        float3 w = info.normalLight;
-        float3 u = normalize(cross(abs(w.x) > 0.1 ? float3(0, 1, 0) : float3(1, 0, 0), w));
-        float3 v = cross(w, u);
-        cam.origin = info.position;
-        cam.direction = normalize(u * cos(r1) * r2s + v * sin(r1) * r2s + w * sqrt(1 - r2));
-        payload.emissive = 0;
-        payload.depth++;
-    }
-    float resolver = float(sample.samplesPerPixel) / float(sample.pass+1);
-    float4 previous = float4(0);
-    if(sample.pass != 0)
-    {
-      previous = accumulator.read(threadId);
-    }
-    float4 result = previous + float4(payload.accumulatedRadiance / float(sample.samplesPerPixel), 0);
-    accumulator.write(result, threadId);
-    image.write(pow(max(result * resolver, 0), float4(0.45f)), threadId);
-}
-
-
-// Screen filling quad in normalized device coordinates.
-constant float2 quadVertices[] = {
-    float2(-1, -1),
-    float2(-1,  1),
-    float2( 1,  1),
-    float2(-1, -1),
-    float2( 1,  1),
-    float2( 1, -1)
-};
-
-struct CopyVertexOut {
-    float4 position [[position]];
-    float2 uv;
-};
-
-// Simple vertex shader that passes through NDC quad positions.
-vertex CopyVertexOut copyVertex(unsigned short vid [[vertex_id]]) {
-    float2 position = quadVertices[vid];
-
-    CopyVertexOut out;
-
-    out.position = float4(position, 0, 1);
-    out.uv = position * 0.5f + 0.5f;
-
-    return out;
-}
-
-// Simple fragment shader that copies a texture and applies a simple tonemapping function.
-fragment float4 copyFragment(CopyVertexOut in [[stage_in]],
-                             texture2d<float> tex)
-{
-    constexpr sampler sam(min_filter::nearest, mag_filter::nearest, mip_filter::none);
-
-    float3 color = tex.sample(sam, in.uv).xyz;
-
-    // Apply a simple tonemapping function to reduce the dynamic range of the
-    // input image into a range which the screen can display.
-    color = color / (1.0f + color);
-
-    return float4(color, 1.0f);
-}
-

src/metal/ComputeKernel.metal

@@ -0,0 +1,357 @@
+#include <metal_stdlib>
+using namespace metal;
+
+// --- Structs (matching C++ and MetalRenderer.mm) ---
+
+struct GPUCamera {
+    float3 cameraPosition;
+    float f;
+    float3 cameraForward;
+    float S_O;
+    float3 fogEmm;
+    float ks;
+    float A;
+    float ka;
+    float2 sensorSize;
+    uint width;
+    uint height;
+};
+
+struct MaterialParameter {
+    float4 albedo_alpha;      // xyz: albedo, w: alpha
+    float4 specularColor_sh; // xyz: specularColor, w: shininess
+    float4 emissive_type;     // xyz: emissive, w: materialType (as float)
+
+    float3 shade(float3 normal, float3 viewDir, float3 lightDir, float3 lightColor) const {
+        float3 albedo = albedo_alpha.xyz;
+        float shininess = specularColor_sh.w;
+        float diffuse = max(dot(normal, lightDir), 0.0);
+        float3 h = normalize(lightDir + viewDir);
+        float specular = pow(clamp(dot(normal, h), 0.0, 1.0), shininess);
+
+        return (albedo * diffuse * lightColor) + (specularColor_sh.xyz * specular * lightColor);
+    }
+};
+
+struct ModelReference {
+    uint32_t positionOffset;
+    uint32_t numPositions;
+    uint32_t indicesOffset;
+    uint32_t numIndices;
+    uint32_t materialIndex;
+};
+
+struct PointLight {
+    float3 position;
+    float pad;
+    float3 color;
+    float attenuation;
+};
+
+struct DirectionalLight {
+    float3 direction;
+    float pad;
+    float3 color;
+    float pad1;
+};
+
+struct SampleParams {
+    uint pass;
+    uint samplesPerPixel;
+    uint numDirectionalLights;
+    uint numPointLights;
+    uint numModels;
+};
+
+// --- Ray-triangle intersection (Möller-Trumbore) ---
+
+// Returns t (distance along ray) if hit, or FLT_MAX if no intersection.
+// Writes barycentric coordinates into *bcwOut when it hits.
+static float rayTriangle(float3 ro, float3 rd, float3 v0, float3 v1, float3 v2,
+                         thread float* tOut, thread float2* bcwOut) {
+    const float EPSILON = 1e-8;
+    float3 edge1 = v1 - v0;
+    float3 edge2 = v2 - v0;
+    float3 h     = cross(rd, edge2);
+    float a      = dot(edge1, h);
+    if (a > -EPSILON && a < EPSILON)
+        return FLT_MAX;  // ray parallel to triangle
+    float f = 1.0 / a;
+    float3 s = ro - v0;
+    float u  = f * dot(s, h);
+    if (u < 0.0 || u > 1.0)
+        return FLT_MAX;
+    float3 q = cross(s, edge1);
+    float v  = f * dot(rd, q);
+    if (v < 0.0 || u + v > 1.0)
+        return FLT_MAX;
+    // t must be positive and within ray bounds
+    float tt = f * dot(edge2, q);
+    if (tt < EPSILON)
+        return FLT_MAX;
+    *tOut  = tt;
+    *bcwOut = float2(u, v);
+    return tt;}
+
+// Test ray against all triangles of all models. Returns closest hit info or FLT_MAX.
+struct HitInfo {
+    float   t;
+    uint    modelIndex;
+    uint    primIndex;
+    float2  bary;
+};
+
+static HitInfo intersectAll(
+    device const uint32_t* indexBuf,
+    device const float*    posBuf,
+    device const ModelReference* models,
+    uint numModels,
+    float3 ro,
+    float3 rd)
+{
+    HitInfo hit = { FLT_MAX, 0u, 0u, float2(0.0) };
+
+    for (uint m = 0; m < numModels; ++m) {
+        uint idxOff  = models[m].indicesOffset;
+        uint vtxOff  = models[m].positionOffset;
+        uint triCount = models[m].numIndices / 3;
+        for (uint t = 0u; t < triCount; ++t) {
+            uint i0 = idxOff + 3 * t + 0;
+            uint i1 = idxOff + 3 * t + 1;
+            uint i2 = idxOff + 3 * t + 2;
+
+            float3 v0 = float3(posBuf[vtxOff + 3*i0],     posBuf[vtxOff + 3*i0+1],   posBuf[vtxOff + 3*i0+2]);
+            float3 v1 = float3(posBuf[vtxOff + 3*i1],     posBuf[vtxOff + 3*i1+1],   posBuf[vtxOff + 3*i1+2]);
+            float3 v2 = float3(posBuf[vtxOff + 3*i2],     posBuf[vtxOff + 3*i2+1],   posBuf[vtxOff + 3*i2+2]);
+
+            float hitT;
+            float2 hitBC;
+            float tt = rayTriangle(ro, rd, v0, v1, v2, &hitT, &hitBC);
+            if (tt < hit.t) {
+                hit.t      = tt;
+                hit.modelIndex  = m;
+                hit.primIndex  = t;
+                hit.bary     = hitBC;
+            }
+        }
+    }
+    return hit;
+}
+
+// Shadow variant — returns true if any triangle blocks the ray within distance 'dist'.
+static bool isBlocked(
+    device const uint32_t* indexBuf,
+    device const float*    posBuf,
+    device const ModelReference* models,
+    uint numModels,
+    float3 ro,
+    float3 rd,
+    float dist)
+{
+    for (uint m = 0; m < numModels; ++m) {
+        uint idxOff  = models[m].indicesOffset;
+        uint vtxOff  = models[m].positionOffset;
+        uint triCount = models[m].numIndices / 3;
+        for (uint t = 0u; t < triCount; ++t) {
+            uint i0 = idxOff + 3 * t + 0;
+            uint i1 = idxOff + 3 * t + 1;
+            uint i2 = idxOff + 3 * t + 2;
+
+            float3 v0 = float3(posBuf[vtxOff + 3*i0],     posBuf[vtxOff + 3*i0+1],   posBuf[vtxOff + 3*i0+2]);
+            float3 v1 = float3(posBuf[vtxOff + 3*i1],     posBuf[vtxOff + 3*i1+1],   posBuf[vtxOff + 3*i1+2]);
+            float3 v2 = float3(posBuf[vtxOff + 3*i2],     posBuf[vtxOff + 3*i2+1],   posBuf[vtxOff + 3*i2+2]);
+
+            float hitT;
+            float2 hitBC;
+            float tt = rayTriangle(ro, rd, v0, v1, v2, &hitT, &hitBC);
+            if (tt < dist) return true;
+        }
+    }
+    return false;
+}
+
+// --- Helpers ---
+
+float3 rand01(uint3 x) {
+    for (int i = 3; i > 0; --i) {
+        x = ((x >> 8u) ^ x.yzx) * 1103515245u;
+    }
+    return float3(x) * (1.0 / 4294967295.0); // 1/0xFFFFFFFF
+}
+
+// --- Kernels ---
+
+kernel void computeKernel(
+    device uint32_t* indexBuffer   [[ buffer(0) ]],
+    device float*    positions      [[ buffer(1) ]],
+    device float2*   texCoords      [[ buffer(2) ]],
+    device float3*   normals        [[ buffer(3) ]],
+    device ModelReference* modelData [[ buffer(4) ]],
+    device MaterialParameter* materialData [[ buffer(5) ]],
+    device DirectionalLight* directionalLights [[ buffer(6) ]],
+    device PointLight* pointLights   [[ buffer(7) ]],
+    device float*    instanceBuffer_dummy [[ buffer(8) ]], 
+    texture2d<float, access::write> accumulator [[ texture(0) ]],
+    texture2d<float, access::write> image      [[ texture(1) ]],
+    constant GPUCamera& gpuCam     [[ buffer(10) ]],
+    constant SampleParams& pSamps  [[ buffer(11) ]],
+    uint2 threadId                 [[thread_position_in_grid]]
+) {
+    if (threadId.x >= gpuCam.width || threadId.y >= gpuCam.height)
+        return;
+
+    uint pass     = pSamps.pass;
+    uint spp      = pSamps.samplesPerPixel;
+    if (pass >= spp)
+        return;
+
+    // -- Camera setup --
+    float3 camPos   = gpuCam.cameraPosition;
+    float3 camFwd   = gpuCam.cameraForward;
+    float  S_O      = gpuCam.S_O;
+    float2 sdim     = gpuCam.sensorSize;
+
+    float3 cx = -normalize(cross(camFwd, abs(camFwd.y) < 0.9 ? float3(0,1,0) : float3(0,0,1)));
+    float3 cy = cross(camFwd, cx);
+
+    float S_I = (S_O * gpuCam.f) / (S_O - gpuCam.f);
+
+    // -- Sample sensor with tent filter + dither --
+    float3 rnd = rand01(uint3(threadId.x, threadId.y, pass));
+    float2 rnd2 = 2.0 * float2(rnd.xy); // tent filter
+    float2 tent = float2(
+        rnd2.x < 1 ? sqrt(rnd2.x) - 1 : 1 - sqrt(2 - rnd2.x),
+        rnd2.y < 1 ? sqrt(rnd2.y) - 1 : 1 - sqrt(2 - rnd2.y));
+    float2 s = ((float2(threadId) + 0.5 * (0.5 + float2((pass / 2) % 2, pass % 2) + tent))
+                 / float2(gpuCam.width, gpuCam.height) - 0.5) * sdim;
+
+    float3 lc = camPos + camFwd * 0.035; // sample on 3d sensor plane
+    [[maybe_unused]]
+    float3 spos = camPos + cx * s.x + cy * s.y;
+
+    // -- Lens (Aperture) / DOF --
+    float3 lensN = -camFwd;
+    float3 lensX = cross(lensN, float3(0,1,0));
+    float3 lensY = cross(lensN, lensX);
+    float2 rndL  = rand01(uint3(threadId.x, threadId.y, pass + 100)).xy;
+    float3 lensSample = lc + (rndL.x - 0.5) * gpuCam.A * lensX + (rndL.y - 0.5) * gpuCam.A * lensY;
+
+    float3 focalPoint = camPos + (S_O + S_I) * camFwd;
+
+    float3 rayOrg   = lensSample;
+    float3 rayDirF  = normalize(focalPoint - lensSample);
+
+    // -- Path Tracing Loop --
+    float3 accumulatedRadiance = float3(0.0);
+    float3 throughput            = float3(1.0);
+
+    for (int bounce = 0; bounce < 4; ++bounce) {
+        // Manual ray-triangle intersection against all scene triangles
+        HitInfo hit = intersectAll(indexBuffer, positions, modelData, pSamps.numModels, rayOrg, rayDirF);
+
+        if (hit.t < FLT_MAX) {
+            uint instanceIndex = hit.modelIndex;
+            uint primitiveIndex = hit.primIndex;
+            float2 bcw         = hit.bary;
+            float3 bary        = float3(1.0 - bcw.x - bcw.y, bcw.x, bcw.y);
+
+            ModelReference m = modelData[instanceIndex];
+            uint idxOff  = m.indicesOffset;
+            uint vtxOff  = m.positionOffset;
+
+            uint v0_idx = vtxOff + indexBuffer[idxOff + 3*primitiveIndex + 0];
+            uint v1_idx = vtxOff + indexBuffer[idxOff + 3*primitiveIndex + 1];
+            uint v2_idx = vtxOff + indexBuffer[idxOff + 3*primitiveIndex + 2];
+
+            // Interpolate position, normal, texCoords (barycentric)
+            float3 p0 = float3(positions[3*v0_idx], positions[3*v0_idx+1], positions[3*v0_idx+2]);
+            [[maybe_unused]] float2 t0 = texCoords[v0_idx];
+            float3 n0 = normals[v0_idx];
+
+            float3 p1 = float3(positions[3*v1_idx], positions[3*v1_idx+1], positions[3*v1_idx+2]);
+            [[maybe_unused]] float2 t1 = texCoords[v1_idx];
+            float3 n1 = normals[v1_idx];
+
+            float3 p2 = float3(positions[3*v2_idx], positions[3*v2_idx+1], positions[3*v2_idx+2]);
+            [[maybe_unused]] float2 t2 = texCoords[v2_idx];
+            float3 n2 = normals[v2_idx];
+
+            float3 pos  = p0 * bary.x + p1 * bary.y + p2 * bary.z;
+            // tex = t0*bary.x + t1*bary.y + t2*bary.z; // for texture lookups
+            float3 norm = normalize(n0 * bary.x + n1 * bary.y + n2 * bary.z);
+
+            MaterialParameter mat = materialData[m.materialIndex];
+
+            // Emissive contribution
+            accumulatedRadiance += throughput * mat.emissive_type.xyz;
+
+            // --- Direct Lighting (NEE) ---
+            float3 directLight = float3(0);
+
+            for (uint j = 0; j < pSamps.numDirectionalLights; ++j) {
+                float3 lDir = -directionalLights[j].direction;
+                if (!isBlocked(indexBuffer, positions, modelData, pSamps.numModels,
+                               pos + norm * 0.001, lDir, FLT_MAX)) {
+                    directLight += mat.shade(norm, -rayDirF, lDir, directionalLights[j].color);
+                }
+            }
+
+            for (uint j = 0; j < pSamps.numPointLights; ++j) {
+                float3 lVec = pointLights[j].position - pos;
+                float3 lDir = normalize(lVec);
+                float dist  = length(lVec);
+                if (!isBlocked(indexBuffer, positions, modelData, pSamps.numModels,
+                               pos + norm * 0.001, lDir, dist)) {
+                    directLight += mat.shade(norm, -rayDirF, lDir, pointLights[j].color)
+                                   * (1.0 / (dist * dist + 1.0));
+                }
+            }
+            accumulatedRadiance += throughput * directLight;
+
+            // --- Indirect Lighting (cosine-weighted hemisphere sampling) ---
+            float3 rnd_ind = rand01(uint3(threadId.x, threadId.y, pass + bounce + 200));
+            float r1 = 2.0 * M_PI_F * rnd_ind.x;
+            float r2 = rnd_ind.y;
+            float r2s = sqrt(r2);
+
+            float3 w = norm;
+            float3 u = normalize(cross(abs(w.x) > 0.1 ? float3(0,1,0) : float3(1,0,0), w));
+            float3 v = cross(w, u);
+            float3 nextDir = normalize(u * cos(r1) * r2s + v * sin(r1) * r2s + w * sqrt(1.0 - r2));
+
+            throughput *= mat.albedo_alpha.xyz;
+
+            rayOrg   = pos + norm * 0.001;
+            rayDirF  = nextDir;
+
+            if (length(throughput) < 0.01) break;
+        } else {
+            // No hit — sky color
+            accumulatedRadiance += throughput * float3(0.05, 0.05, 0.1);
+            break;
+        }
+    }
+
+    image.write(float4(accumulatedRadiance, 1.0), threadId);
+}
+
+// --- Quad rendering shaders (pass-through) ---
+
+struct VertexOut {
+    float4 position [[position]];
+    float2 uv;
+};
+
+vertex VertexOut copyVertex(uint vid [[vertex_id]]) {
+    VertexOut out;
+    float2 pos = float2((float)((vid << 1) & 2), (float)(vid & 2));
+    out.position = float4(pos * 2.0 - 1.0, 0.0, 1.0);
+    out.uv = pos;
+    return out;
+}
+
+fragment float4 copyFragment(VertexOut in [[stage_in]],
+                             texture2d<float, access::sample> tex [[texture(0)]]) {
+    sampler s(mag_filter::linear, min_filter::linear);
+    return tex.sample(s, in.uv);
+}

src/metal/MetalRenderer.h

@@ -28,6 +28,7 @@ struct SampleParams
   uint samplesPerPixel;
   uint numDirectionalLights;
   uint numPointLights;
+  uint numModels;
 };
 
 class MetalRenderer : public Renderer

src/metal/MetalRenderer.mm

@@ -2,14 +2,23 @@
 #include "metal/MetalScene.h"
 #include "scene/Renderer.h"
 #include "util/Camera.h"
+#include <Foundation/Foundation.h>
 #include <GLFW/glfw3.h>
+#include <filesystem>
+#include <fstream>
 #include <imgui.h>
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_metal.h>
+#include <iostream>
+#include <mutex>
+#include <sstream>
+#include <string>
+#include <vector>
 
 NSWindow* window;
 CAMetalLayer* metalLayer;
 id<CAMetalDrawable> drawable;
+id<MTLTexture> texToDraw;
 
 id<MTLDevice> device;
 id<MTLLibrary> library;
@@ -19,35 +28,46 @@ id<MTLComputePipelineState> computePipeline;
 id<MTLTexture> accumulator = nullptr;
 id<MTLTexture> resultTexture = nullptr;
 
+static std::mutex g_metal_mtx;
+
 MTLRenderPassDescriptor* renderPass;
 id<MTLRenderCommandEncoder> renderEncoder;
 id<MTLCommandBuffer> renderCmd;
 id<MTLRenderPipelineState> pipelineState;
 
-static void glfw_error_callback(int error, const char* description)
+static void glfw_error_callback(int error, const char* description) { fprintf(stderr, "Glfw Error %d: %s\n", error, description); }
-{
-    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
-}
 MetalRenderer::MetalRenderer()
 {
   width = 1920;
   height = 1080;
+  texToDraw = nullptr;
   device = MTLCreateSystemDefaultDevice();
 
-  library = [device newDefaultLibrary];
-  if (!library) {
   NSError* error = nil;
-    NSURL* url = [NSURL fileURLWithPath:@"../src/metal/Compute.metallib"];
+  MTLCompileOptions* compileOptions = [[MTLCompileOptions alloc] init];
-    library = [device newLibraryWithURL:url error:&error];
+  std::string shaderSource;
-    if (!library) {
+  {
-      fprintf(stderr, "Failed to load library from %s: %s\n", [url path], [[error localizedDescription] UTF8String]);
+    // Note: Adjust path based on where you run the binary from
+    std::ifstream shaderFile("../src/metal/ComputeKernel.metal");
+    if (!shaderFile.is_open())
+    {
+      std::cerr << "Failed to open shader file!" << std::endl;
+      return;
     }
+    std::stringstream buffer;
+    buffer << shaderFile.rdbuf();
+    shaderSource = buffer.str();
   }
 
+  library = [device newLibraryWithSource:[NSString stringWithUTF8String:shaderSource.c_str()] options:compileOptions error:&error];
+  if(error)
+  {
+    std::cerr << "Failed to compile shader: " << [[error localizedDescription] UTF8String] << std::endl;
+    return;
+  }
   queue = [device newCommandQueue];
   scene = new MetalScene(device, queue);
   function = [library newFunctionWithName:@"computeKernel"];
-  NSError* error;
   computePipeline = [device newComputePipelineStateWithFunction:function error:&error];
 
   IMGUI_CHECKVERSION();
@@ -82,12 +102,20 @@ MetalRenderer::MetalRenderer()
 
   pipelineState = [device newRenderPipelineStateWithDescriptor:renderDescriptor error:&error];
 
+  // Create persistent compute-result textures once.
+  MTLTextureDescriptor* texDesc = [[MTLTextureDescriptor alloc] init];
+  [texDesc setWidth:1920];
+  [texDesc setHeight:1080];
+  [texDesc setPixelFormat:MTLPixelFormatRGBA32Float];
+  [texDesc setUsage:MTLTextureUsageShaderWrite | MTLTextureUsageShaderRead];
+  resultTexture = [device newTextureWithDescriptor:texDesc];
+  accumulator   = [device newTextureWithDescriptor:texDesc];
+  [texDesc release];
+
   [renderDescriptor release];
 }
 
-MetalRenderer::~MetalRenderer() {
+MetalRenderer::~MetalRenderer() { [renderPass release]; }
-  [renderPass release];
-}
 
 void MetalRenderer::addPointLight(PointLight point) { scene->addPointLight(point); }
 void MetalRenderer::addDirectionalLight(DirectionalLight dir) { scene->addDirectionalLight(dir); }
@@ -97,13 +125,14 @@ void MetalRenderer::generate() { scene->generate(); }
 
 void MetalRenderer::beginFrame()
 {
-  @autoreleasepool {
+  @autoreleasepool
+  {
 
     glfwPollEvents();
     int w, h;
     glfwGetFramebufferSize(handle, &w, &h);
-  framebufferWidth = width;
+    framebufferWidth = w;
-  framebufferHeight = height;
+    framebufferHeight = h;
     metalLayer.drawableSize = CGSizeMake(framebufferWidth, framebufferHeight);
     drawable = [metalLayer nextDrawable];
     renderCmd = [queue commandBuffer];
@@ -112,12 +141,22 @@ void MetalRenderer::beginFrame()
     renderPass.colorAttachments[0].loadAction = MTLLoadActionClear;
     renderPass.colorAttachments[0].storeAction = MTLStoreActionStore;
     ImGui_ImplMetal_NewFrame(renderPass);
+    ;
     ImGui_ImplGlfw_NewFrame();
     ImGui::NewFrame();
     renderEncoder = [renderCmd renderCommandEncoderWithDescriptor:renderPass];
     [renderEncoder setRenderPipelineState:pipelineState];
 
-    [renderEncoder setFragmentTexture:resultTexture atIndex:0];
+    id<MTLTexture> tex;
+    {
+      std::lock_guard<std::mutex> lock(g_metal_mtx);
+      tex = resultTexture;
+      if (tex)
+        [tex retain];
+    }
+    texToDraw = tex;
+
+    [renderEncoder setFragmentTexture:texToDraw atIndex:0];
 
     // Draw a quad which fills the screen.
     [renderEncoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:6];
@@ -130,7 +169,8 @@ void MetalRenderer::beginFrame()
 
 void MetalRenderer::update()
 {
-  @autoreleasepool {
+  @autoreleasepool
+  {
     ImGui::Render();
     ImGui_ImplMetal_RenderDrawData(ImGui::GetDrawData(), renderCmd, renderEncoder);
     [renderEncoder endEncoding];
@@ -139,6 +179,12 @@ void MetalRenderer::update()
     [renderCmd commit];
     [renderCmd release];
     [drawable release];
+
+    if (texToDraw)
+    {
+      [texToDraw release];
+      texToDraw = nullptr;
+    }
   }
 }
 
@@ -146,33 +192,24 @@ void MetalRenderer::render(Camera camera, RenderParameter parameter)
 {
   GPUCamera gpuCam = {
       .cameraPosition = camera.position,
-      .A = camera.A,
-      .cameraForward = camera.target - camera.position,
       .f = camera.f,
+      .cameraForward = camera.target - camera.position,
       .S_O = camera.S_O,
+      .fogEmm = glm::vec3(0, 0, 0),
+      .ks = 0,
+      .A = camera.A,
+      .ka = 0,
       .sensorSize = camera.sensorSize,
       .width = parameter.width,
       .height = parameter.height,
   };
 
-  if(accumulator != nullptr)
-  {
-    [accumulator release];
-    [resultTexture release];
-  }
-    MTLTextureDescriptor* texDescriptor = [[MTLTextureDescriptor alloc] init];
-    [texDescriptor setWidth:parameter.width];
-    [texDescriptor setHeight:parameter.height];
-    [texDescriptor setPixelFormat:MTLPixelFormatRGBA32Float];
-    [texDescriptor setUsage:MTLTextureUsageShaderWrite | MTLTextureUsageShaderRead];
-    accumulator = [device newTextureWithDescriptor:texDescriptor];
-    resultTexture = [device newTextureWithDescriptor:texDescriptor];
-  [texDescriptor release];
   for (uint i = 0; i < parameter.numSamples; ++i)
   {
     if (!running)
       return;
-    @autoreleasepool{
+    @autoreleasepool
+    {
       id<MTLCommandBuffer> cmdBuffer = [queue commandBuffer];
       id<MTLComputeCommandEncoder> encoder = [cmdBuffer computeCommandEncoder];
       // cmdBuffer->addCompletedHandler([this](MTL::CommandBuffer* cmdBuffer)
@@ -183,6 +220,7 @@ void MetalRenderer::render(Camera camera, RenderParameter parameter)
           .samplesPerPixel = parameter.numSamples,
           .numDirectionalLights = scene->getNumDirLights(),
           .numPointLights     = scene->getNumPointLights(),
+          .numModels          = scene->getNumModels(),
       };
       [encoder setComputePipelineState:computePipeline];
       [encoder setBuffer:scene->indicesBuffer offset:0 atIndex:0];
@@ -198,6 +236,10 @@ void MetalRenderer::render(Camera camera, RenderParameter parameter)
       {
         [encoder setBuffer:scene->directionalLightBuffer offset:0 atIndex:6];
       }
+      if (scene->getNumPointLights() > 0)
+      {
+        [encoder setBuffer:scene->pointLightBuffer offset:0 atIndex:7];
+      }
       [encoder setBuffer:scene->instanceBuffer offset:0 atIndex:8];
       [encoder setAccelerationStructure:scene->accelerationStructure atBufferIndex:9];
       [encoder setTexture:accumulator atIndex:0];

src/metal/MetalScene.mm

@@ -40,7 +40,7 @@ void MetalScene::createRayTracingHierarchy()
   for (uint i = 0; i < refs.size(); ++i)
   {
     MTLAccelerationStructureTriangleGeometryDescriptor* descriptor = [MTLAccelerationStructureTriangleGeometryDescriptor descriptor];
-    descriptor.triangleCount = refs[i].numIndices;
+    descriptor.triangleCount = refs[i].numIndices / 3;
     descriptor.indexBuffer = indicesBuffer;
     descriptor.indexBufferOffset = refs[i].indicesOffset * sizeof(glm::uvec3);
     descriptor.indexType = MTLIndexTypeUInt32;

src/scene/Scene.h

@@ -41,6 +41,7 @@ public:
 
   constexpr uint32_t getNumDirLights() const { return (uint)directionalLights.size(); }
   constexpr uint32_t getNumPointLights() const { return (uint)pointLights.size(); }
+  constexpr uint32_t getNumModels()      const { return (uint)models.size(); }
 
 protected:
   std::vector<ModelReference> refs;