float PointSet::GetValue ( float x, float y, float z )
{
float dx, dy, dz, dsq;
float sum;
int pndx;
Point* pcurr;
float R2 = 1.8*1.8;
Grid_FindCells ( Vector3DF(x,y,z), m_GridCellsize/2.0 );
int cnt = 0;
sum = 0.0;
for (int cell=0; cell < 8; cell++ ) {
if ( m_GridCell[cell] != -1 ) {
pndx = m_Grid [ m_GridCell[cell] ];
while ( pndx != -1 ) {
pcurr = (Point*) (mBuf[0].data + pndx*mBuf[0].stride);
dx = x - pcurr->pos.x;
dy = y - pcurr->pos.y;
dz = z - pcurr->pos.z;
dsq = dx*dx+dy*dy+dz*dz;
if ( dsq < R2 ) sum += R2 / dsq;
pndx = pcurr->next;
}
}
}
return sum;
}
// Compute Forces - Using spatial grid. Faster.
void FluidSystem::SPH_ComputeForceGrid ()
{
char *dat1, *dat1_end;
Fluid *p;
Fluid *pcurr;
int pndx;
Vector3DF force, fcurr;
register double pterm, vterm, dterm;
double c, d, dsq, r;
double dx, dy, dz;
double mR, mR2, visc;
float radius = m_Param[SPH_SMOOTHRADIUS] / m_Param[SPH_SIMSCALE];
d = m_Param[SPH_SIMSCALE];
mR = m_Param[SPH_SMOOTHRADIUS];
mR2 = (mR*mR);
visc = m_Param[SPH_VISC];
dat1_end = mBuf[0].data + NumPoints()*mBuf[0].stride;
for ( dat1 = mBuf[0].data; dat1 < dat1_end; dat1 += mBuf[0].stride ) {
p = (Fluid*) dat1;
force.Set ( 0, 0, 0 );
Grid_FindCells ( p->pos, radius );
for (int cell=0; cell < 8; cell++) {
if ( m_GridCell[cell] != -1 ) {
pndx = m_Grid [ m_GridCell[cell] ];
while ( pndx != -1 ) {
pcurr = (Fluid*) (mBuf[0].data + pndx*mBuf[0].stride);
if ( pcurr == p ) {pndx = pcurr->next; continue; }
dx = ( p->pos.x - pcurr->pos.x)*d; // dist in cm
dy = ( p->pos.y - pcurr->pos.y)*d;
dz = ( p->pos.z - pcurr->pos.z)*d;
dsq = (dx*dx + dy*dy + dz*dz);
if ( mR2 > dsq ) {
r = sqrt ( dsq );
c = (mR - r);
pterm = -0.5f * c * m_SpikyKern * ( p->pressure + pcurr->pressure) / r;
dterm = c * p->density * pcurr->density;
vterm = m_LapKern * visc;
force.x += ( pterm * dx + vterm * (pcurr->vel_eval.x - p->vel_eval.x) ) * dterm;
force.y += ( pterm * dy + vterm * (pcurr->vel_eval.y - p->vel_eval.y) ) * dterm;
force.z += ( pterm * dz + vterm * (pcurr->vel_eval.z - p->vel_eval.z) ) * dterm;
}
pndx = pcurr->next;
}
}
}
p->sph_force = force;
}
}
// Compute Pressures - Using spatial grid, and also create neighbor table
void FluidSystem::SPH_ComputePressureGrid ()
{
char *dat1, *dat1_end;
Fluid* p;
Fluid* pcurr;
int pndx;
int i, cnt = 0;
float dx, dy, dz, sum, dsq, c;
float d, d2, mR, mR2;
float radius = m_Param[SPH_SMOOTHRADIUS] / m_Param[SPH_SIMSCALE];
d = m_Param[SPH_SIMSCALE];
d2 = d*d;
mR = m_Param[SPH_SMOOTHRADIUS];
mR2 = mR*mR;
dat1_end = mBuf[0].data + NumPoints()*mBuf[0].stride;
i = 0;
for ( dat1 = mBuf[0].data; dat1 < dat1_end; dat1 += mBuf[0].stride, i++ ) {
p = (Fluid*) dat1;
sum = 0.0;
m_NC[i] = 0;
Grid_FindCells ( p->pos, radius );
for (int cell=0; cell < 8; cell++) {
if ( m_GridCell[cell] != -1 ) {
pndx = m_Grid [ m_GridCell[cell] ];
while ( pndx != -1 ) {
pcurr = (Fluid*) (mBuf[0].data + pndx*mBuf[0].stride);
if ( pcurr == p ) {pndx = pcurr->next; continue; }
dx = ( p->pos.x - pcurr->pos.x)*d; // dist in cm
dy = ( p->pos.y - pcurr->pos.y)*d;
dz = ( p->pos.z - pcurr->pos.z)*d;
dsq = (dx*dx + dy*dy + dz*dz);
if ( mR2 > dsq ) {
c = m_R2 - dsq;
sum += c * c * c;
if ( m_NC[i] < MAX_NEIGHBOR ) {
m_Neighbor[i][ m_NC[i] ] = pndx;
m_NDist[i][ m_NC[i] ] = sqrt(dsq);
m_NC[i]++;
}
}
pndx = pcurr->next;
}
}
m_GridCell[cell] = -1;
}
p->density = sum * m_Param[SPH_PMASS] * m_Poly6Kern ;
p->pressure = ( p->density - m_Param[SPH_RESTDENSITY] ) * m_Param[SPH_INTSTIFF];
p->density = 1.0f / p->density;
}
}
Vector3DF PointSet::GetGradient ( float x, float y, float z )
{
Vector3DF norm;
float dx, dy, dz, dsq;
float sum;
int pndx;
Point* pcurr;
float R2 = (m_GridCellsize/2.0)*(m_GridCellsize/2.0);
Grid_FindCells ( Vector3DF(x,y,z), m_GridCellsize/2.0 );
int cnt = 0;
sum = 0.0;
norm.Set (0,0,0);
for (int cell=0; cell < 8; cell++ ) {
if ( m_GridCell[cell] != -1 ) {
pndx = m_Grid [ m_GridCell[cell] ];
while ( pndx != -1 ) {
pcurr = (Point*) (mBuf[0].data + pndx*mBuf[0].stride);
dx = x - pcurr->pos.x;
dy = y - pcurr->pos.y;
dz = z - pcurr->pos.z;
dsq = dx*dx+dy*dy+dz*dz;
if ( dsq > 0 && dsq < R2 ) {
dsq = 2.0*R2 / (dsq*dsq);
norm.x += dx * dsq;
norm.y += dy * dsq;
norm.z += dz * dsq;
}
pndx = pcurr->next;
}
}
}
norm.Normalize ();
return norm;
}
DWORD PointSet::GetColor ( float x, float y, float z )
{
Vector3DF clr;
float dx, dy, dz, dsq;
float sum;
int pndx;
Point* pcurr;
float R2 = (m_GridCellsize/2.0)*(m_GridCellsize/2.0);
Grid_FindCells ( Vector3DF(x,y,z), m_GridCellsize/2.0 );
int cnt = 0;
sum = 0.0;
clr.Set (0,0,0);
for (int cell=0; cell < 8; cell++ ) {
if ( m_GridCell[cell] != -1 ) {
pndx = m_Grid [ m_GridCell[cell] ];
while ( pndx != -1 ) {
pcurr = (Point*) (mBuf[0].data + pndx*mBuf[0].stride);
dx = x - pcurr->pos.x;
dy = y - pcurr->pos.y;
dz = z - pcurr->pos.z;
dsq = dx*dx+dy*dy+dz*dz;
if ( dsq < R2 ) {
dsq = 2.0*R2 / (dsq*dsq);
clr.x += RED(pcurr->clr) * dsq;
clr.y += GRN(pcurr->clr) * dsq;
clr.z += BLUE(pcurr->clr) * dsq;
}
pndx = pcurr->next;
}
}
}
clr.Normalize ();
return COLORA(clr.x, clr.y, clr.z, 1.0);
}
