Method Update

trinity/Particle/Tr2ParticleSystem.cpp:485–544

-------------------------------------------------------------------------------------- Description: Per-frame update method for the system. Updates particle system state. Arguments: globalArguments - Child emitter update arguments --------------------------------------------------------------------------------------

//   globalArguments - Child emitter update arguments
// --------------------------------------------------------------------------------------
void Tr2ParticleSystem::Update( const ITr2GenericEmitter::UpdateArguments& globalArguments )
{
	CCP_STATS_ZONE( __FUNCTION__ );

	auto arguments = globalArguments;
	arguments.parentTransform = m_worldTransform;


	if( m_previousDataOutdated )
	{
		float* gpuBuffer = m_buffers[Tr2ParticleElementData::GPU];
		uint32_t gpuDataSize = m_vertexSizes[Tr2ParticleElementData::GPU];
		uint32_t gpuDataHalfSize = gpuDataSize >> 1;

		for( uint32_t i = 0; i < m_aliveCount; ++i )
		{
			//Save the current data so we have the previous frame's data for motion vectors
			//This kinda has to be done regardless of if we tick or not, to make sure it's always up to date for rendering...
			std::copy(
				gpuBuffer + i * gpuDataSize,
				gpuBuffer + i * gpuDataSize + gpuDataHalfSize,
				gpuBuffer + i * gpuDataSize + gpuDataHalfSize );
		}

		m_previousDataOutdated = false;
	}

	// if we're offscreen or very small, we can tick less frequently
	if( m_updatePeriod > 1 )
	{
		++m_updatePeriodClock;
		m_updatePeriodClock %= m_updatePeriod;
		if( m_updatePeriodClock != 0 )
		{
			return;
		}
	}

	if( m_lastUpdate == 0 )
	{
		m_lastUpdate = arguments.time;
	}
	float dt = std::min( TimeAsFloat( arguments.time - m_lastUpdate ), 1.0f / 3.0f );
	m_lastUpdate = arguments.time;

	//include considerable hysteresis in toggling sorting.
	//Things to consider:
	// frametime breakpoints as global constant/setting/per-system?
	// re-enable a limited number of systems per frame?
	if( dt > 0.035f && m_sortingAllowed )
	{
		m_sortingAllowed = false;
	}
	else if( !m_sortingAllowed && dt < 0.02f )
	{
		m_sortingAllowed = true;
	}