Method ApplyConstraint

trinity/Particle/Tr2SphereConstraint.cpp:99–260

-------------------------------------------------------------------------------------- Description: Implements ITr2GenericParticleConstraint interface. Checks for collision between a particle and a sphere. If collision is detected optionally applies physical response to particle position and/or velocity and run generators to re-generate particle data components. This method can be called asyncrono

//   dt - Frame time.
// --------------------------------------------------------------------------------------
void Tr2SphereConstraint::ApplyConstraint( const ITr2GenericEmitter::UpdateArguments& arguments, float** particles, unsigned* strides, unsigned count, float dt )
{
	if( !m_isValid )
	{
		return;
	}

	Tr2ParallelFor(
		Tr2BlockedRange<size_t>( 0, count, 100 ),
		[=]( const Tr2BlockedRange<size_t>& range ) -> void {
			XMVECTOR refPosition = m_position;
			XMVECTOR refRadius = XMVectorReplicate( m_radius );
			XMVECTOR invert = XMVectorReplicate( m_invertSphere ? -1.f : 1.f );
			XMVECTOR radiusCmp = XMVectorMultiply( invert, XMVectorMultiply( refRadius, refRadius ) );
			XMVECTOR particleRadiusCoefficient = m_particleRadiusCoefficient;

			Tr2ParticleStreamIterator<XMFLOAT3> position( particles, strides, m_positionElement );
			position += int( range.begin() );
			Tr2ParticleStreamIterator<XMFLOAT4> radiusStream( particles, strides, m_radiusElement );
			radiusStream += int( range.begin() );
			Tr2ParticleStreamIterator<XMFLOAT3> velocity( particles, strides, m_velocityElement );
			velocity += int( range.begin() );

			for( auto i = range.begin(); i < range.end(); ++i, ++position, ++radiusStream, ++velocity )
			{
				XMVECTOR radius = refRadius;
				if( m_radiusElement.m_offset != -1 )
				{
					if( m_invertSphere )
					{
						radius = XMVectorSubtract( radius, XMVector4Dot( XMLoadFloat4( radiusStream ), particleRadiusCoefficient ) );
					}
					else
					{
						radius = XMVectorAdd( radius, XMVector4Dot( XMLoadFloat4( radiusStream ), particleRadiusCoefficient ) );
					}
				}
				XMVECTOR curPosition = XMLoadFloat3( position );
				XMVECTOR curVelocity = XMLoadFloat3( velocity );
				XMVECTOR offset = XMVectorSubtract( curPosition, refPosition );
				XMVECTOR offsetLengthSq = XMVector3LengthSq( offset );

				// Check if the particle is inside the "prohibited space"
				if( XMVectorGetIntX( XMVectorLess( XMVectorMultiply( offsetLengthSq, invert ), radiusCmp ) ) )
				{
					if( m_affectPosition )
					{
						offset = XMVectorMultiply( offset, XMVectorReciprocal( XMVectorSqrt( offsetLengthSq ) ) );
						XMVECTOR newPosition = XMVectorMultiplyAdd( offset, radius, refPosition );
						XMStoreFloat3( position, newPosition );

						if( m_affectVelocity && m_velocityElement.m_offset != -1 )
						{
							offset = XMVectorMultiply( offset, invert );

							XMVECTOR velocityDot = XMVector3Dot( curVelocity, offset );
							if( XMVectorGetIntX( XMVectorLess( velocityDot, XMVectorZero() ) ) )
							{