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#include "ctranslate.h"
#include <math.h>
// TODO remove dublicate pi definitions
#define PI 3.14159265359
void csystem_init(csystem_t *cs, vector_t *up)
{
cs->up = up;
// Create new coordinate system where N is up. To do this we need two more vectors for the other axises.
// Create the 2. by setting x or y to 0
if (up->x > up->y) {
vector_set(&cs->ax, up->z, 0, -up->x);
} else {
vector_set(&cs->ax, 0, -up->z, up->y);
}
// Normalice
vector_scale_inv(&cs->ax, &cs->ax, vector_len(&cs->ax));
// Create the 3. axis by taking the cross of the other
vector_cross(&cs->az, up, &cs->ax);
}
void csystem_calc_real(csystem_t *cs, vector_t *inside, vector_t *real)
{
vector_set(real, inside->x * cs->ax.x + inside->y * cs->up->x + inside->z * cs->az.x,
inside->x * cs->ax.y + inside->y * cs->up->y + inside->z * cs->az.y,
inside->x * cs->ax.z + inside->y * cs->up->z + inside->z * cs->az.z);
}
void csystem_hemisphere_random(csystem_t *cs, COORD_T r1, COORD_T r2, vector_t *out)
{
COORD_T sinTheta = sqrt(1 - r1 * r1);
COORD_T phi = 2 * PI * r2;
// Calculate the random direction vector
vector_set(out, sinTheta * cos(phi), r1, sinTheta * sin(phi));
}
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