Ray Query opaque shadows

Author: JoseEmilio-ARM

attachments/38_ray_tracing.cpp

@@ -195,7 +195,8 @@ class HelloTriangleApplication {
         vk::KHRCreateRenderpass2ExtensionName,
         vk::KHRAccelerationStructureExtensionName,
         vk::KHRBufferDeviceAddressExtensionName,
-        vk::KHRDeferredHostOperationsExtensionName
+        vk::KHRDeferredHostOperationsExtensionName,
+        vk::KHRRayQueryExtensionName
     };
 
     void initWindow() {
@@ -372,7 +373,8 @@ class HelloTriangleApplication {
                 vk::PhysicalDeviceVulkan12Features,
                 vk::PhysicalDeviceVulkan13Features,
                 vk::PhysicalDeviceExtendedDynamicStateFeaturesEXT,
-                vk::PhysicalDeviceAccelerationStructureFeaturesKHR>();
+                vk::PhysicalDeviceAccelerationStructureFeaturesKHR,
+                vk::PhysicalDeviceRayQueryFeaturesKHR>();
             bool supportsRequiredFeatures = features.template get<vk::PhysicalDeviceFeatures2>().features.samplerAnisotropy &&
                                             features.template get<vk::PhysicalDeviceVulkan13Features>().dynamicRendering &&
                                             features.template get<vk::PhysicalDeviceExtendedDynamicStateFeaturesEXT>().extendedDynamicState &&
@@ -382,7 +384,8 @@ class HelloTriangleApplication {
                                             features.template get<vk::PhysicalDeviceVulkan12Features>().runtimeDescriptorArray &&
                                             features.template get<vk::PhysicalDeviceVulkan12Features>().shaderSampledImageArrayNonUniformIndexing &&
                                             features.template get<vk::PhysicalDeviceVulkan12Features>().bufferDeviceAddress &&
-                                            features.template get<vk::PhysicalDeviceAccelerationStructureFeaturesKHR>().accelerationStructure;
+                                            features.template get<vk::PhysicalDeviceAccelerationStructureFeaturesKHR>().accelerationStructure &&
+                                            features.template get<vk::PhysicalDeviceRayQueryFeaturesKHR>().rayQuery;
 
             return supportsVulkan1_3 && supportsGraphics && supportsAllRequiredExtensions && supportsRequiredFeatures;
           } );
@@ -447,14 +450,15 @@ class HelloTriangleApplication {
         // query for Vulkan 1.3 features
         vk::StructureChain<vk::PhysicalDeviceFeatures2, vk::PhysicalDeviceVulkan12Features,
             vk::PhysicalDeviceVulkan13Features, vk::PhysicalDeviceExtendedDynamicStateFeaturesEXT,
-            vk::PhysicalDeviceAccelerationStructureFeaturesKHR> featureChain = {
-                {.features = {.samplerAnisotropy = true } },            // vk::PhysicalDeviceFeatures2
+            vk::PhysicalDeviceAccelerationStructureFeaturesKHR, vk::PhysicalDeviceRayQueryFeaturesKHR> featureChain = {
+                {.features = {.samplerAnisotropy = true } },                       // vk::PhysicalDeviceFeatures2
                 {.shaderSampledImageArrayNonUniformIndexing = true, .descriptorBindingSampledImageUpdateAfterBind = true,
                  .descriptorBindingPartiallyBound = true, .descriptorBindingVariableDescriptorCount = true,
-                 .runtimeDescriptorArray = true, .bufferDeviceAddress = true }, // vk::PhysicalDeviceVulkan12Features
-                {.synchronization2 = true, .dynamicRendering = true },  // vk::PhysicalDeviceVulkan13Features
-                {.extendedDynamicState = true },                         // vk::PhysicalDeviceExtendedDynamicStateFeaturesEXT
-                {.accelerationStructure = true },                         // vk::PhysicalDeviceAccelerationStructureFeaturesKHR
+                 .runtimeDescriptorArray = true, .bufferDeviceAddress = true },    // vk::PhysicalDeviceVulkan12Features
+                {.synchronization2 = true, .dynamicRendering = true },             // vk::PhysicalDeviceVulkan13Features
+                {.extendedDynamicState = true },                                   // vk::PhysicalDeviceExtendedDynamicStateFeaturesEXT
+                {.accelerationStructure = true },                                  // vk::PhysicalDeviceAccelerationStructureFeaturesKHR
+                {.rayQuery = true }                                                // vk::PhysicalDeviceRayQueryFeaturesKHR
         };
 
         // create a Device
@@ -1002,14 +1006,10 @@ class HelloTriangleApplication {
             vk::AccelerationStructureGeometryDataKHR geomData(trianglesData);
             vk::AccelerationStructureGeometryKHR blasGeometry{
                 .geometryType = vk::GeometryTypeKHR::eTriangles,
-                .geometry = geomData
+                .geometry = geomData,
+                .flags = vk::GeometryFlagBitsKHR::eOpaque
             };
 
-            if (!submesh.alphaCut)
-            {
-                blasGeometry.flags = vk::GeometryFlagBitsKHR::eOpaque;
-            }
-
             vk::AccelerationStructureBuildRangeInfoKHR blasRangeInfo{
                 .primitiveCount = static_cast<uint32_t>(submesh.indexCount / 3),
                 .primitiveOffset = 0,

attachments/38_ray_tracing.slang

@@ -22,6 +22,7 @@ struct VSOutput
     float3 fragColor;
     float2 fragTexCoord;
     float3 fragNormal;
+    float3 worldPos;
 };
 
 [shader("vertex")]
@@ -31,6 +32,7 @@ VSOutput vertMain(VSInput input) {
     output.fragColor = input.inColor;
     output.fragTexCoord = input.inTexCoord;
     output.fragNormal = input.inNormal;
+    output.worldPos = mul(ubo.model, float4(input.inPosition, 1.0)).xyz;
     return output;
 }
 
@@ -46,7 +48,46 @@ struct PushConstant {
 [push_constant]
 PushConstant pc;
 
+static const float3 lightDir = float3(-6.0, 0.0, 6.0);
+
+// Small epsilon to avoid self-intersection
+static const float EPSILON = 0.01;
+
+bool in_shadow(float3 P)
+{
+    // Build the shadow ray from the world position toward the light
+    RayDesc shadowRayDesc;
+    shadowRayDesc.Origin = P;
+    shadowRayDesc.Direction = normalize(lightDir);
+    shadowRayDesc.TMin = EPSILON;
+    shadowRayDesc.TMax = 1e4;
+
+    // Initialize a ray-query for shadows
+    RayQuery<RAY_FLAG_SKIP_PROCEDURAL_PRIMITIVES |
+             RAY_FLAG_ACCEPT_FIRST_HIT_AND_END_SEARCH> sq;
+    let rayFlags = RAY_FLAG_SKIP_PROCEDURAL_PRIMITIVES |
+             RAY_FLAG_ACCEPT_FIRST_HIT_AND_END_SEARCH;
+
+    sq.TraceRayInline(accelerationStructure, rayFlags, 0xFF, shadowRayDesc);
+
+    sq.Proceed();
+
+    // If the shadow ray intersects an opaque triangle, we consider the pixel in shadow
+    bool hit = (sq.CommittedStatus() == COMMITTED_TRIANGLE_HIT);
+
+    return hit;
+}
+
 [shader("fragment")]
 float4 fragMain(VSOutput vertIn) : SV_TARGET {
-   return textures[pc.materialIndex].Sample(textureSampler, vertIn.fragTexCoord);
+   float4 baseColor = textures[pc.materialIndex].Sample(textureSampler, vertIn.fragTexCoord);
+
+   bool inShadow = in_shadow(vertIn.worldPos);
+
+   // Darken if in shadow
+   if (inShadow) {
+       baseColor.rgb *= 0.2;
+   }
+
+   return baseColor;
 }

attachments/CMakeLists.txt

@@ -89,7 +89,7 @@ function (add_slang_shader_target TARGET)
   )
   add_custom_command (
           OUTPUT  ${SHADERS_DIR}/slang.spv
-          COMMAND ${SLANGC_EXECUTABLE} ${SHADER_SOURCES} -target spirv -profile spirv_1_4 -emit-spirv-directly -fvk-use-entrypoint-name ${ENTRY_POINTS} -o slang.spv
+          COMMAND ${SLANGC_EXECUTABLE} ${SHADER_SOURCES} -target spirv -profile spirv_1_4+spvRayQueryKHR -emit-spirv-directly -fvk-use-entrypoint-name ${ENTRY_POINTS} -o slang.spv
           WORKING_DIRECTORY ${SHADERS_DIR}
           DEPENDS ${SHADERS_DIR} ${SHADER_SOURCES}
           COMMENT "Compiling Slang Shaders"