//////////////////////////////////////////////////////////////////////
// Advect using the MacCormack method from the Selle paper
//////////////////////////////////////////////////////////////////////
void FLUID_3D::advectMacCormack()
{
Vec3Int res = Vec3Int(_xRes,_yRes,_zRes);
if(DOMAIN_BC_LEFT == 0) copyBorderX(_xVelocity, res);
else setZeroX(_xVelocity, res);
if(DOMAIN_BC_TOP == 0) copyBorderY(_yVelocity, res);
else setZeroY(_yVelocity, res);
if(DOMAIN_BC_FRONT == 0) copyBorderZ(_zVelocity, res);
else setZeroZ(_zVelocity, res);
SWAP_POINTERS(_xVelocity, _xVelocityOld);
SWAP_POINTERS(_yVelocity, _yVelocityOld);
SWAP_POINTERS(_zVelocity, _zVelocityOld);
SWAP_POINTERS(_density, _densityOld);
SWAP_POINTERS(_heat, _heatOld);
const float dt0 = _dt / _dx;
// use force arrays as temp arrays
for (int x = 0; x < _totalCells; x++)
_xForce[x] = _yForce[x] = 0.0;
float* t1 = _xForce;
float* t2 = _yForce;
advectFieldMacCormack(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _densityOld, _density, t1,t2, res, _obstacles);
advectFieldMacCormack(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _heatOld, _heat, t1,t2, res, _obstacles);
advectFieldMacCormack(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _xVelocityOld, _xVelocity, t1,t2, res, _obstacles);
advectFieldMacCormack(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _yVelocityOld, _yVelocity, t1,t2, res, _obstacles);
advectFieldMacCormack(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _zVelocityOld, _zVelocity, t1,t2, res, _obstacles);
if(DOMAIN_BC_LEFT == 0) copyBorderX(_xVelocity, res);
else setZeroX(_xVelocity, res);
if(DOMAIN_BC_TOP == 0) copyBorderY(_yVelocity, res);
else setZeroY(_yVelocity, res);
if(DOMAIN_BC_FRONT == 0) copyBorderZ(_zVelocity, res);
else setZeroZ(_zVelocity, res);
setZeroBorder(_density, res);
setZeroBorder(_heat, res);
for (int x = 0; x < _totalCells; x++)
t1[x] = t2[x] = 0.0;
}
//////////////////////////////////////////////////////////////////////
// Advect using the MacCormack method from the Selle paper
//////////////////////////////////////////////////////////////////////
void FLUID_3D::advectMacCormackEnd2(int zBegin, int zEnd)
{
const float dt0 = _dt / _dx;
Vec3Int res = Vec3Int(_xRes,_yRes,_zRes);
// use force array as temp arrays
float* t1 = _xForce;
// advectFieldMacCormack2(dt, xVelocity, yVelocity, zVelocity, oldField, newField, tempfield, temp, res, obstacles)
advectFieldMacCormack2(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _densityOld, _density, _densityTemp, t1, res, _obstacles, zBegin, zEnd);
advectFieldMacCormack2(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _heatOld, _heat, _heatTemp, t1, res, _obstacles, zBegin, zEnd);
advectFieldMacCormack2(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _xVelocityOld, _xVelocityTemp, _xVelocity, t1, res, _obstacles, zBegin, zEnd);
advectFieldMacCormack2(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _yVelocityOld, _yVelocityTemp, _yVelocity, t1, res, _obstacles, zBegin, zEnd);
advectFieldMacCormack2(dt0, _xVelocityOld, _yVelocityOld, _zVelocityOld, _zVelocityOld, _zVelocityTemp, _zVelocity, t1, res, _obstacles, zBegin, zEnd);
if(_domainBcLeft == 0) copyBorderX(_xVelocityTemp, res, zBegin, zEnd);
else setZeroX(_xVelocityTemp, res, zBegin, zEnd);
if(_domainBcFront == 0) copyBorderY(_yVelocityTemp, res, zBegin, zEnd);
else setZeroY(_yVelocityTemp, res, zBegin, zEnd);
if(_domainBcTop == 0) copyBorderZ(_zVelocityTemp, res, zBegin, zEnd);
else setZeroZ(_zVelocityTemp, res, zBegin, zEnd);
setZeroBorder(_density, res, zBegin, zEnd);
setZeroBorder(_heat, res, zBegin, zEnd);
/*int begin=zBegin * _slabSize;
int end=begin + (zEnd - zBegin) * _slabSize;
for (int x = begin; x < end; x++)
_xForce[x] = _yForce[x] = 0.0f;*/
}
void FLUID_3D::advectMacCormackBegin(int zBegin, int zEnd)
{
Vec3Int res = Vec3Int(_xRes,_yRes,_zRes);
if(_domainBcLeft == 0) copyBorderX(_xVelocityOld, res, zBegin, zEnd);
else setZeroX(_xVelocityOld, res, zBegin, zEnd);
if(_domainBcFront == 0) copyBorderY(_yVelocityOld, res, zBegin, zEnd);
else setZeroY(_yVelocityOld, res, zBegin, zEnd);
if(_domainBcTop == 0) copyBorderZ(_zVelocityOld, res, zBegin, zEnd);
else setZeroZ(_zVelocityOld, res, zBegin, zEnd);
}
//////////////////////////////////////////////////////////////////////
// project into divergence free field
//////////////////////////////////////////////////////////////////////
void FLUID_3D::project()
{
int x, y, z;
size_t index;
float *_pressure = new float[_totalCells];
float *_divergence = new float[_totalCells];
memset(_pressure, 0, sizeof(float)*_totalCells);
memset(_divergence, 0, sizeof(float)*_totalCells);
setObstacleBoundaries(_pressure);
// copy out the boundaries
if(DOMAIN_BC_LEFT == 0) setNeumannX(_xVelocity, _res);
else setZeroX(_xVelocity, _res);
if(DOMAIN_BC_TOP == 0) setNeumannY(_yVelocity, _res);
else setZeroY(_yVelocity, _res);
if(DOMAIN_BC_FRONT == 0) setNeumannZ(_zVelocity, _res);
else setZeroZ(_zVelocity, _res);
// calculate divergence
index = _slabSize + _xRes + 1;
for (z = 1; z < _zRes - 1; z++, index += 2 * _xRes)
for (y = 1; y < _yRes - 1; y++, index += 2)
for (x = 1; x < _xRes - 1; x++, index++)
{
float xright = _xVelocity[index + 1];
float xleft = _xVelocity[index - 1];
float yup = _yVelocity[index + _xRes];
float ydown = _yVelocity[index - _xRes];
float ztop = _zVelocity[index + _slabSize];
float zbottom = _zVelocity[index - _slabSize];
if(_obstacles[index+1]) xright = - _xVelocity[index];
if(_obstacles[index-1]) xleft = - _xVelocity[index];
if(_obstacles[index+_xRes]) yup = - _yVelocity[index];
if(_obstacles[index-_xRes]) ydown = - _yVelocity[index];
if(_obstacles[index+_slabSize]) ztop = - _zVelocity[index];
if(_obstacles[index-_slabSize]) zbottom = - _zVelocity[index];
_divergence[index] = -_dx * 0.5f * (
xright - xleft +
yup - ydown +
ztop - zbottom );
// DG: commenting this helps CG to get a better start, 10-20% speed improvement
// _pressure[index] = 0.0f;
}
copyBorderAll(_pressure);
// solve Poisson equation
solvePressurePre(_pressure, _divergence, _obstacles);
setObstaclePressure(_pressure);
// project out solution
float invDx = 1.0f / _dx;
index = _slabSize + _xRes + 1;
for (z = 1; z < _zRes - 1; z++, index += 2 * _xRes)
for (y = 1; y < _yRes - 1; y++, index += 2)
for (x = 1; x < _xRes - 1; x++, index++)
{
if(!_obstacles[index])
{
_xVelocity[index] -= 0.5f * (_pressure[index + 1] - _pressure[index - 1]) * invDx;
_yVelocity[index] -= 0.5f * (_pressure[index + _xRes] - _pressure[index - _xRes]) * invDx;
_zVelocity[index] -= 0.5f * (_pressure[index + _slabSize] - _pressure[index - _slabSize]) * invDx;
}
}
if (_pressure) delete[] _pressure;
if (_divergence) delete[] _divergence;
}