inline
void update_forces(particle_t* pi, particle_t* pj, float h2, float rho0,
float C0, float Cp, float Cv, float* pia, float* pja) {
float dx[3];
vec3_diff(dx, pi->x, pj->x);
float r2 = vec3_len2(dx);
if (r2 < h2) {
const float rhoi = pi->rho;
const float rhoj = pj->rho;
float q = sqrt(r2 / h2);
float u = 1 - q;
float w0 = C0 * u / rhoi / rhoj;
float wp = w0 * Cp * (rhoi + rhoj - 2 * rho0) * u / q;
float wv = w0 * Cv;
float dv[3];
vec3_diff(dv, pi->v, pj->v);
// Equal and opposite pressure forces
vec3_saxpy(pia, wp, dx);
vec3_saxpy(pja, -wp, dx);
// Equal and opposite viscosity forces
vec3_saxpy(pia, wv, dv);
vec3_saxpy(pja, -wv, dv);
}
}
union vec3 *vec3_normalize(union vec3 *vo, const union vec3 *vi)
{
float len = sqrt(vec3_len2(vi));
vo->v.x = vi->v.x / len;
vo->v.y = vi->v.y / len;
vo->v.z = vi->v.z / len;
return vo;
}
int nearest_faction(union vec3 v)
{
int i;
double len;
int winner = 0;
union vec3 distv;
for (i = 0; i < nfactions(); i++) {
double dist;
vec3_sub(&distv, &v, &fact[i].center);
dist = vec3_len2(&distv);
if (i == 0 || dist < len) {
len = dist;
winner = i;
}
}
return winner;
}
static void add_subdivided_triangle(
triangle trg,
float edge_length_limit2,
triangle** output,
size_t* count,
size_t* allocated
) {
if(edge_length_limit2 > 0.0f) {
// If the longest edge of the triangle has length larger than the limit,
// then we split that edge.
float maxval = -1.0f;
int maxval_i = 0;
for(int i = 0; i < 3; ++i) {
int j = (i + 1) % 3;
float val = vec3_len2(vec3_sub(trg.corners[i], trg.corners[j]));
if(val > maxval) {
maxval = val;
maxval_i = i;
}
}
if(maxval > edge_length_limit2) {
triangle trg1 = trg;
triangle trg2 = trg;
int i = maxval_i;
int j = (i + 1) % 3;
int k = (j + 1) % 3;
// We don't split exactly at the center to have some nice randomness
// in the triangles.
double t = 0.4f + 0.2f * (double)rand() / (double)RAND_MAX;
vec3 split = vec3_add(
vec3_mul(trg.corners[i], 1.0f - t),
vec3_mul(trg.corners[j], t)
);
trg1.corners[0] = split;
trg1.corners[1] = trg.corners[k];
trg1.corners[2] = trg.corners[i];
trg2.corners[0] = split;
trg2.corners[1] = trg.corners[j];
trg2.corners[2] = trg.corners[k];
add_subdivided_triangle(
trg1, edge_length_limit2, output, count, allocated
);
add_subdivided_triangle(
trg2, edge_length_limit2, output, count, allocated
);
return;
}
}
++(*count);
while((*count) > (*allocated)) {
(*allocated) *= 2;
*output = checked_realloc2(*output, *allocated, sizeof(triangle));
}
(*output)[(*count) - 1] = trg;
}
