webgpu triangle

interfaces/Crafter.Graphics-RT.cppm

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+/*
+Crafter®.Graphics
+Copyright (C) 2026 Catcrafts®
+catcrafts.net
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License version 3.0 as published by the Free Software Foundation;
+*/
+
+// Portable RT types & constants.
+//
+// Native: aliases the Vulkan struct so existing code that passes
+// `RenderingElement3D::instance` directly into vkCmdBuildAccelerationStructuresKHR
+// is a no-op layout-wise.
+// DOM: provides a POD with the same byte layout + the same field names, so
+// user code touching `instance.mask`, `instance.flags`, `instance.transform`
+// etc. compiles unchanged.
+//
+// Flag constants are spelled out as Crafter::kRT* so portable user code can
+// avoid referencing VK_* on the DOM target. The values match
+// VkGeometryInstanceFlagBitsKHR / VkRayTracingShaderGroupTypeKHR so the
+// constants compare-equal on Vulkan if the user wants to mix surfaces.
+
+module;
+#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
+#include "vulkan/vulkan.h"
+#endif
+export module Crafter.Graphics:RT;
+import std;
+
+export namespace Crafter {
+#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
+    using RTTransformMatrix = VkTransformMatrixKHR;
+    using RTInstance        = VkAccelerationStructureInstanceKHR;
+#else
+    // Mirrors VkTransformMatrixKHR: row-major affine 3x4.
+    struct RTTransformMatrix {
+        float matrix[3][4];
+    };
+    static_assert(sizeof(RTTransformMatrix) == 48);
+
+    // Mirrors VkAccelerationStructureInstanceKHR byte-for-byte.
+    // On WebGPU the `accelerationStructureReference` slot holds the BLAS
+    // handle returned by MeshWebGPU::blasHandle (a u32 widened to u64).
+    struct RTInstance {
+        RTTransformMatrix transform;
+        std::uint32_t instanceCustomIndex                    : 24;
+        std::uint32_t mask                                   : 8;
+        std::uint32_t instanceShaderBindingTableRecordOffset : 24;
+        std::uint32_t flags                                  : 8;
+        std::uint64_t accelerationStructureReference;
+    };
+    static_assert(sizeof(RTInstance) == 64);
+#endif
+
+    // VkGeometryInstanceFlagBitsKHR mirror. Values verbatim so equal on both.
+    inline constexpr std::uint8_t kRTGeometryInstanceTriangleFacingCullDisable = 0x1;
+    inline constexpr std::uint8_t kRTGeometryInstanceTriangleFlipFacing        = 0x2;
+    inline constexpr std::uint8_t kRTGeometryInstanceForceOpaque               = 0x4;
+    inline constexpr std::uint8_t kRTGeometryInstanceForceNoOpaque             = 0x8;
+
+    // Hit-group identification. Matches VkRayTracingShaderGroupTypeKHR for
+    // the two types we actually support (general + triangles-hit).
+    enum class RTShaderGroupType : std::uint8_t {
+        General           = 0,   // raygen / miss / callable
+        TrianglesHitGroup = 1,
+    };
+
+    // Cross-backend description of one entry in the shader-group array
+    // passed to PipelineRT::Init. Mirrors the meaningful subset of
+    // VkRayTracingShaderGroupCreateInfoKHR: per group, the type and the
+    // indices (into the SBT's shader array) for general / closestHit /
+    // anyHit, with kRTShaderUnused == VK_SHADER_UNUSED_KHR for "none".
+    inline constexpr std::uint32_t kRTShaderUnused = 0xFFFFFFFFu;
+
+    struct RTShaderGroup {
+        RTShaderGroupType type             = RTShaderGroupType::General;
+        std::uint32_t      generalShader    = kRTShaderUnused;
+        std::uint32_t      closestHitShader = kRTShaderUnused;
+        std::uint32_t      anyHitShader     = kRTShaderUnused;
+    };
+}