Function UpdateResource

Source/Engine/Streaming/Streaming.cpp:116–203

}

void UpdateResource(StreamableResource* resource, double currentTime)
{
    ASSERT(resource && resource->CanBeUpdated());

    // Pick group and handler dedicated for that resource
    auto group = resource->GetGroup();
    auto handler = group->GetHandler();

    // Calculate target quality for that asset
    float targetQuality = 1.0f;
    if (resource->IsDynamic())
    {
        targetQuality = handler->CalculateTargetQuality(resource, currentTime);
        targetQuality = Math::Saturate(targetQuality);
    }

    // Update quality smoothing
    resource->Streaming.QualitySamples.Add(targetQuality);
    targetQuality = resource->Streaming.QualitySamples.Maximum();
    targetQuality = Math::Saturate(targetQuality);

    // Calculate target residency level (discrete value)
    auto maxResidency = resource->GetMaxResidency();
    auto currentResidency = resource->GetCurrentResidency();
    auto allocatedResidency = resource->GetAllocatedResidency();
    auto targetResidency = handler->CalculateResidency(resource, targetQuality);
    ASSERT(allocatedResidency >= currentResidency && allocatedResidency >= 0);
    resource->Streaming.LastUpdateTime = currentTime;

    // Check if a target residency level has been changed
    if (targetResidency != resource->Streaming.TargetResidency)
    {
        // Register change
        resource->Streaming.TargetResidency = targetResidency;
        resource->Streaming.TargetResidencyChangeTime = currentTime;
    }

    // Check if need to change resource current residency
    if (handler->RequiresStreaming(resource, currentResidency, targetResidency))
    {
        // Check if need to change allocation for that resource
        if (allocatedResidency != targetResidency)
        {
            // Update resource allocation
            Task* allocateTask = resource->UpdateAllocation(targetResidency);
            if (allocateTask)
            {
                // When resource wants to perform reallocation on a task then skip further updating until it's done
                allocateTask->Start();
                resource->RequestStreamingUpdate();
                return;
            }
            else if (resource->GetAllocatedResidency() < targetResidency)
            {
                // Allocation failed (eg. texture format is not supported or run out of memory)
                resource->ResetStreaming();
                return;
            }