ray_tracing_scene.hpp

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#pragma once
 
#include "vulkan_common.hpp"
 
#include <cstdint>
#include <glm/glm.hpp>
#include <optional>
#include <vector>
 
namespace renderer {
class VulkanCore;
 
class RayTracingScene {
public:
  struct Instance {
    glm::mat4 transform {1.0f};
    vk::DeviceAddress blas_address = 0;
    uint32_t custom_index = 0;
    uint8_t mask = 0xFF;
    bool deforming = false;
  };
 
  RayTracingScene(const VulkanCore& core, uint32_t frames_in_flight);
 
  void beginFrame();
 
  void addInstance(const Instance& instance);
 
  void build(vk::CommandBuffer cmd, uint32_t frame_index, bool tracing);
 
  [[nodiscard]]
  auto getAccelerationStructure(uint32_t frame_index) const -> vk::AccelerationStructureKHR;

  [[nodiscard]]
  auto getAccelerationStructureGeneration(uint32_t frame_index) const -> uint64_t {
    return frame_index < m_frames.size() ? m_frames[frame_index].tlas_generation : 0;
  }
 
  [[nodiscard]]
  auto getInstanceCount() const noexcept -> uint32_t {
    return static_cast<uint32_t>(m_instances.size());
  }
 
  static constexpr uint32_t k_max_instances = 8192;
 
  static constexpr uint32_t k_max_refits_before_rebuild = 240;
 
private:
  struct FrameResources {
    std::optional<vma::raii::Buffer> instance_buffer;
    std::optional<vma::raii::Buffer> tlas_buffer;
    std::optional<vma::raii::Buffer> scratch;
    vk::raii::AccelerationStructureKHR tlas = nullptr;
    uint64_t tlas_generation = 0;
    uint32_t built_instances = 0;
 
    std::vector<Instance> built;
    uint32_t refits_since_build = 0;
  };
 
  const VulkanCore* m_core = nullptr;
  std::vector<FrameResources> m_frames;
  std::vector<Instance> m_instances;

  PFN_vkCmdBuildAccelerationStructuresKHR m_build_acceleration_structures = nullptr;
};
 
}