Method Allocate

trinity/Eve/EveInstancedMeshManager.cpp:369–403

EveInstancedMeshManager::InstanceBuffer::Allocation EveInstancedMeshManager::InstanceBuffer::Allocate( uint32_t count )
{
	USE_MAIN_THREAD_RENDER_CONTEXT();

	auto frameNumber = renderContext.GetRecordingFrameNumber();

	auto offset = GetUnusedRegion( count );
	if( !offset.has_value() )
	{
		if( mappedData )
		{
			mappedRetiredBuffers.push_back( buffer.get() );
			mappedData = nullptr;
		}
		auto oldCount = buffer ? buffer->GetDesc().count : 0;
		retiredBuffers.push_back( std::move( buffer ) );
		buffer = std::make_unique<Tr2BufferAL>();
		uint32_t newCount = std::max( count, oldCount ? oldCount * 2 : 128 * 1024 );
		buffer->Create( 4, newCount, Tr2GpuUsage::VERTEX_BUFFER, Tr2CpuUsage::WRITE_OFTEN | Tr2CpuUsage::NON_SYNCRONIZED_WRITE, nullptr, renderContext );
		regions.clear();
		offset = 0;
	}

	buffer->MapForWriting( mappedData, renderContext );

	if( !regions.empty() && regions.back().recordedFrame == frameNumber && regions.back().offset + regions.back().length == offset )
	{
		regions.back().length += count;
	}
	else
	{
		regions.push_back( { offset.value(), count, frameNumber } );
	}
	return { buffer.get(), mappedData + offset.value(), offset.value() };
}

std::optional<uint32_t> EveInstancedMeshManager::InstanceBuffer::GetUnusedRegion( uint32_t count )
{