Method UpdateViewDependentData

trinity/Particle/Tr2ParticleSystem.cpp:1021–1065

-------------------------------------------------------------------------------------- Description: Called before particle system is used for rendering. Optionally sorts particles and updates vertex buffer if needed. --------------------------------------------------------------------------------------

//   and updates vertex buffer if needed.
// --------------------------------------------------------------------------------------
void Tr2ParticleSystem::UpdateViewDependentData( const TriFrustum* frustum, const Matrix& worldTransform )
{
	CCP_STATS_ZONE( __FUNCTION__ );

	m_shouldSortVisible = false;

	m_worldTransform = worldTransform;

	if( !m_bufferDirty && !m_requiresSorting )
	{
		return;
	}

	if( !m_vertexBuffer.IsValid() )
	{
		return;
	}

	m_shouldSortVisible = true;
	m_updatePeriod = 1;
	if( frustum )
	{
		Vector3 minB, maxB;
		//If we were about to sort, first check that this system is visible and large enough to warrant sorting
		if( GetBoundingBox( minB, maxB ) )
		{
			Vector3 centre( ( maxB + minB ) * 0.5f );
			const Vector3 extent( ( maxB - minB ) * 0.5f );

			//use the contained sphere rather than circumscribing sphere, just to be a little conservative
			float radius = std::max( std::abs( extent.x ), std::max( std::abs( extent.y ), std::abs( extent.z ) ) );
			radius *= Length( m_worldTransform.GetX() );

			centre = Vector3( XMVector3TransformCoord( centre, m_worldTransform ) );
			const Vector4 boundingSphere = Vector4( centre.x, centre.y, centre.z, radius );

			if( !frustum->IsSphereVisible( &boundingSphere ) )
			{
				m_shouldSortVisible = false;
				// update every fourth frame
				m_updatePeriod = 4;
			}
		}
	}
}

void Tr2ParticleSystem::SortParticles()
{