// adjust fluid to terrain, compute sph parameters
void adjust_fluid(fluid* f, lp_grid lpg, aabb faabb, aabb taabb)
{
float height = faabb.max.getY() - taabb.min.getY();
float v_max = sqrt(2 * G * height);
float cs = v_max / sqrt(MAX_DENSITY_FLUCTUATION);
f->ideal_k = WATER_IDEAL_K;
f->tait_b = WATER_TAIT_B;
// dt to match MAX_DENSITY_FLUCTUATION between ticks
f->dt = COURANT * f->particle_radius / v_max;
// measure and store max density and samples in the initial fluid
// configuration in order to adjust later sph computations
clear_particle_data(lpg);
std::vector<interaction> interactions = collect_interactions(lpg);
compute_densities(interactions, lpg.step);
int max_samples = 0;
float max_density = 0;
for(particle* pp=f->particles; pp<f->particles + f->particle_count; pp++) {
if (pp->samples > max_samples) {
max_samples = pp->samples;
max_density = pp->density;
}
}
f->max_samples = (float) max_samples;
f->density_factor = f->density / (max_density * f->particle_mass);
printf("FLUID ADJUSTMENT INFO:\n");
printf("dt = %f\n", f->dt);
printf("max_density = %f\n", max_density);
printf("max_samples = %d\n", max_samples);
printf("density_factor = %f\n\n", f->density_factor);
}
void apply_sph(fluid_sim* fsimp)
{
clear_particle_data(fsimp->lpg);
std::vector<interaction> interactions = collect_interactions(fsimp->lpg);
compute_densities(interactions, fsimp->lpg.step);
compute_pressures(fsimp->f);
apply_forces(interactions, fsimp->f);
}
static void
rescale_layout_polarFocus(v_data * graph, int n,
double *x_coords, double *y_coords,
double x_focus, double y_focus, int interval, double distortion)
{
// Polar distortion - auxiliary function
int i;
double *densities = NULL, *smoothed_densities = NULL;
double *distances = N_NEW(n, double);
double *orig_distances = N_NEW(n, double);
int *ordering;
double ratio;
for (i = 0; i < n; i++)
{
distances[i] = DIST(x_coords[i], y_coords[i], x_focus, y_focus);
}
cpvec(orig_distances, 0, n - 1, distances);
ordering = N_NEW(n, int);
for (i = 0; i < n; i++)
{
ordering[i] = i;
}
quicksort_place(distances, ordering, 0, n - 1);
densities = compute_densities(graph, n, x_coords, y_coords);
smoothed_densities = smooth_vec(densities, ordering, n, interval, smoothed_densities);
// rescale distances
if (distortion < 1.01 && distortion > 0.99)
{
for (i = 1; i < n; i++)
{
distances[ordering[i]] = distances[ordering[i - 1]] + (orig_distances[ordering[i]] -
orig_distances[ordering
[i -
1]]) / smoothed_densities[ordering[i]];
}
} else
{
double factor;
// just to make milder behavior:
if (distortion >= 0)
{
factor = sqrt(distortion);
}
else
{
factor = -sqrt(-distortion);
}
for (i = 1; i < n; i++)
{
distances[ordering[i]] =
distances[ordering[i - 1]] + (orig_distances[ordering[i]] -
orig_distances[ordering
[i -
1]]) /
pow(smoothed_densities[ordering[i]], factor);
}
}
// compute new coordinate:
for (i = 0; i < n; i++)
{
if (orig_distances[i] == 0)
{
ratio = 0;
}
else
{
ratio = distances[i] / orig_distances[i];
}
x_coords[i] = x_focus + (x_coords[i] - x_focus) * ratio;
y_coords[i] = y_focus + (y_coords[i] - y_focus) * ratio;
}
free(densities);
free(smoothed_densities);
free(distances);
free(orig_distances);
free(ordering);
}
