Method Read

Source/Engine/GraphicsDevice/WebGPU/GPUDeviceWebGPU.cpp:107–149

}

bool GPUQuerySetWebGPU::Read(uint32 index, uint64& result, bool wait)
{
    if (_state == Resolved)
    {
        // Start mapping the buffer
        ASSERT(!wait); // TODO: impl wgpuBufferMapAsync with waiting (see GPUBufferWebGPU::Map)
        WGPUBufferMapCallbackInfo callback = WGPU_BUFFER_MAP_CALLBACK_INFO_INIT;
        callback.mode = WGPUCallbackMode_AllowSpontaneous;
        callback.userdata1 = this;
        callback.callback = [](WGPUMapAsyncStatus status, WGPUStringView message, WGPU_NULLABLE void* userdata1, WGPU_NULLABLE void* userdata2)
        {
            if (status == WGPUMapAsyncStatus_Success)
            {
                auto set = (GPUQuerySetWebGPU*)userdata1;
                set->OnRead();
            }
#if !BUILD_RELEASE
            else
            {
                LOG(Error, "Query Set map failed with status {}, {}", (uint32)status, WEBGPU_TO_STR(message));
            }
#endif
        };
        wgpuBufferMapAsync(_readBuffer, WGPUMapMode_Read, 0, _index * sizeof(uint64), callback);
        _state = Mapping;
    }
    else if (_state == Mapped)
    {
        // Read the results from mapped buffer
        if (Type == GPUQueryType::Timer)
        {
            // Timestamp calculates a difference between two queries (begin/end) in nanoseconds (result is in microseconds)
            result = Math::Max(_mapped[index + 1] - _mapped[index], 0ull) / 1000;
        }
        else
        {
            // Occlusion outputs number of fragment samples that pass all the tests (scissor, stencil, depth, etc.)
            result = _mapped[index];
        }
        return true;
    }
    return false;
}

void GPUQuerySetWebGPU::OnRead()
{