src/dawn/native/vulkan/FramebufferFetchHelper.h

// Copyright 2026 The Dawn & Tint Authors
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#ifndef SRC_DAWN_NATIVE_VULKAN_FRAMEBUFFER_FETCH_H_
#define SRC_DAWN_NATIVE_VULKAN_FRAMEBUFFER_FETCH_H_

#include "src/dawn/common/MutexProtected.h"
#include "src/dawn/common/Ref.h"
#include "src/dawn/common/vulkan_platform.h"
#include "src/dawn/native/Commands.h"
#include "src/dawn/native/vulkan/DescriptorSetAllocator.h"
#include "src/dawn/native/vulkan/ResourceTableVk.h"
#include "src/dawn/native/vulkan/VulkanInfo.h"

namespace dawn::native::vulkan {

// Helper to create VkDescriptorSets for binding color attachments as input attachments in order
// to implement FramebufferFetch.
class FramebufferFetchHelper {
  public:
    explicit FramebufferFetchHelper(Device* device);
    ~FramebufferFetchHelper();

    // Returns layout suitable for a render pass with `attachmentCount` color attachments.
    ResultOrError<VkDescriptorSetLayout> GetLayout(uint32_t attachmentCount);

    // Returns a descriptor set that binds all render pass color attachments as input attachments.
    // The returned descriptor set is only valid to use for the current render pass.
    // It will be destroyed after the render pass is submitted to the GPU.
    ResultOrError<VkDescriptorSet> GetDescriptorsForRenderPass(const BeginRenderPassCmd* cmd);

  private:
    struct DescriptorSetHolder {
        VkDescriptorSetLayout layout = VK_NULL_HANDLE;
        Ref<DescriptorSetAllocator> allocator;
    };

    // Returns initialized descriptor set layout and allocator for `attachmentCount`. This is safe
    // to call from any thread.
    ResultOrError<DescriptorSetHolder> GetDescriptorSetData(uint32_t attachmentCount);

    raw_ptr<Device> mDevice;
    MutexProtected<std::array<DescriptorSetHolder, kMaxColorAttachments>> mHolders;
};

}  // namespace dawn::native::vulkan

#endif  // SRC_DAWN_NATIVE_VULKAN_FRAMEBUFFER_FETCH_H_