static void compute_uvw_vectors(struct Camera *cam)
{
double halfu, halfv;
int i;
/* assumes dir and up are normalized */
VEC3_COPY(cam->wvec, cam->dir);
VEC3_NORMALIZE(cam->wvec);
VEC3_CROSS(cam->uvec, cam->wvec, cam->up);
VEC3_NORMALIZE(cam->uvec);
VEC3_CROSS(cam->vvec, cam->uvec, cam->wvec);
VEC3_NORMALIZE(cam->vvec);
halfv = tan(RADIAN(cam->fov/2));
halfu = halfv * cam->aspect;
for (i = 0; i < 3; i++) {
cam->scrn_bottom_left[i] = cam->center[i] +
cam->wvec[i] -
halfu * cam->uvec[i] -
halfv * cam->vvec[i];
}
VEC3_MUL_ASGN(cam->uvec, 2 * halfu);
VEC3_MUL_ASGN(cam->vvec, 2 * halfv);
}
void CamGetRay(const struct Camera *cam, const double *screen_uv, struct Ray *ray)
{
int i;
for (i = 0; i < 3; i++) {
ray->dir[i] =
cam->scrn_bottom_left[i] +
screen_uv[0] * cam->uvec[i] +
screen_uv[1] * cam->vvec[i] -
cam->center[i];
}
VEC3_NORMALIZE(ray->dir);
VEC3_COPY(ray->orig, cam->center);
ray->tmin = cam->znear;
ray->tmax = cam->zfar;
}
void CamGetRay(const struct Camera *cam, const double *screen_uv,
double time, struct Ray *ray)
{
const struct Transform *transform_interp = get_interpolated_transform(cam, time);
double target[3] = {0, 0, 0};
double eye[3] = {0, 0, 0};
compute_ray_target(cam, screen_uv, target);
XfmTransformPoint(transform_interp, target);
XfmTransformPoint(transform_interp, eye);
VEC3_SUB(ray->dir, target, eye);
VEC3_NORMALIZE(ray->dir);
VEC3_COPY(ray->orig, eye);
ray->tmin = cam->znear;
ray->tmax = cam->zfar;
}