download_device_local()

MAYAFLUX_API void MayaFlux::Buffers::download_device_local	(	const std::shared_ptr< VKBuffer > &	source,
		const std::shared_ptr< VKBuffer > &	target,
		const std::shared_ptr< VKBuffer > &	staging_buffer
	)

Download data from a device-local buffer using a staging buffer.

Parameters

source	Source VKBuffer to download data from
target	Target VKBuffer to store the downloaded data
staging_buffer	Host-visible staging VKBuffer used for the download

This function handles downloading data from a device-local VKBuffer by utilizing a staging buffer. It issues a command to copy the data from the device-local buffer to the staging buffer, invalidates the staging buffer memory, and then copies the data into a CPU-accessible format to update the target buffer.

Definition at line 166 of file StagingUtils.cpp.

{
    auto buffer_service = Registry::BackendRegistry::instance()
                              .get_service<Registry::Service::BufferService>();
 
    if (!buffer_service) {
        error<std::runtime_error>(
            Journal::Component::Buffers,
            Journal::Context::BufferProcessing,
            std::source_location::current(),
            "upload_host_visible requires a valid buffer service");
    }
 
    buffer_service->execute_immediate([&](void* ptr) {
        vk::BufferCopy copy_region;
        copy_region.srcOffset = 0;
        copy_region.dstOffset = 0;
        copy_region.size = source->get_size_bytes();
 
        auto cmd = static_cast<vk::CommandBuffer*>(ptr);
 
        cmd->copyBuffer(
            source->get_buffer(),
            staging_buffer->get_buffer(),
            1, &copy_region);
    });
 
    staging_buffer->mark_invalid_range(0, source->get_size_bytes());
 
    auto& staging_resources = staging_buffer->get_buffer_resources();
    auto invalid_ranges = staging_buffer->get_and_clear_invalid_ranges();
    for (auto& [offset, size] : invalid_ranges) {
        buffer_service->invalidate_range(
            staging_resources.memory,
            offset,
            size);
    }
 
    void* staging_mapped = staging_resources.mapped_ptr;
    if (!staging_mapped) {
        error<std::runtime_error>(
            Journal::Component::Buffers,
            Journal::Context::BufferProcessing,
            std::source_location::current(),
            "Staging buffer has no mapped pointer");
    }
 
    std::vector<uint8_t> raw_bytes(source->get_size_bytes());
    std::memcpy(raw_bytes.data(), staging_mapped, source->get_size_bytes());
 
    std::dynamic_pointer_cast<VKBuffer>(target)->set_data({ raw_bytes });
}

References MayaFlux::Journal::BufferProcessing, MayaFlux::Journal::Buffers, MayaFlux::Registry::BackendRegistry::get_service(), and MayaFlux::Registry::BackendRegistry::instance().

Referenced by MayaFlux::Buffers::VKBuffer::clone_to(), MayaFlux::Buffers::BufferDownloadProcessor::download_device_local(), and download_from_gpu().

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