/**
* Rearrange point (x, y) in the HEALPix projection by
* combining the polar caps into two polar squares.
* Put the north polar square in position north_square and
* the south polar square in position south_square.
* If inverse=1, then uncombine the polar caps.
* @param north_square integer between 0 and 3.
* @param south_square integer between 0 and 3.
**/
static XY combine_caps(double x, double y, int north_square, int south_square,
int inverse) {
XY xy;
double v[2];
double a[2];
double vector[2];
double v_min_c[2];
double ret_dot[2];
CapMap capmap = get_cap(x, y, north_square, south_square, inverse);
if (capmap.region == equatorial) {
xy.x = capmap.x;
xy.y = capmap.y;
return xy;
}
v[0] = x;
v[1] = y;
if (inverse == 0) {
/* Rotate (x, y) about its polar cap tip and then translate it to
north_square or south_square. */
int pole = 0;
double (*tmpRot)[2];
double c[2] = {capmap.x, capmap.y};
if (capmap.region == north) {
pole = north_square;
a[0] = (-3.0*M_PI/4.0 + pole*M_PI/2);
a[1] = (M_PI/2.0 + pole*0);
tmpRot = rot[get_rotate_index(capmap.cn - pole)];
vector_sub(v, c, v_min_c);
dot_product(tmpRot, v_min_c, ret_dot);
vector_add(ret_dot, a, vector);
} else {
pole = south_square;
a[0] = (-3.0*M_PI/4.0 + pole*M_PI/2);
a[1] = (M_PI/-2.0 + pole*0);
tmpRot = rot[get_rotate_index(-1*(capmap.cn - pole))];
vector_sub(v, c, v_min_c);
dot_product(tmpRot, v_min_c, ret_dot);
vector_add(ret_dot, a, vector);
}
xy.x = vector[0];
xy.y = vector[1];
return xy;
} else {
/* Inverse function.
Unrotate (x, y) and then translate it back. */
int pole = 0;
double (*tmpRot)[2];
double c[2] = {capmap.x, capmap.y};
/* disassemble */
if (capmap.region == north) {
pole = north_square;
a[0] = (-3.0*M_PI/4.0 + capmap.cn*M_PI/2);
a[1] = (M_PI/2.0 + capmap.cn*0);
tmpRot = rot[get_rotate_index(-1*(capmap.cn - pole))];
vector_sub(v, c, v_min_c);
dot_product(tmpRot, v_min_c, ret_dot);
vector_add(ret_dot, a, vector);
} else {
pole = south_square;
a[0] = (-3.0*M_PI/4.0 + capmap.cn*M_PI/2);
a[1] = (M_PI/-2.0 + capmap.cn*0);
tmpRot = rot[get_rotate_index(capmap.cn - pole)];
vector_sub(v, c, v_min_c);
dot_product(tmpRot, v_min_c, ret_dot);
vector_add(ret_dot, a, vector);
}
xy.x = vector[0];
xy.y = vector[1];
return xy;
}
}
inline void combine_caps(T& xy_x, T& xy_y, int north_square, int south_square,
int inverse)
{
static const T half_pi = detail::half_pi<T>();
static const T fourth_pi = detail::fourth_pi<T>();
T v[2];
T c[2];
T vector[2];
T v_min_c[2];
T ret_dot[2];
const double (*tmpRot)[2];
int pole = 0;
cap_map<T> capmap = get_cap(xy_x, xy_y, north_square, south_square, inverse);
if (capmap.region == cap_map<T>::equatorial) {
xy_x = capmap.x;
xy_y = capmap.y;
return;
}
v[0] = xy_x; v[1] = xy_y;
c[0] = capmap.x; c[1] = capmap.y;
if (inverse == 0) {
/* Rotate (xy_x, xy_y) about its polar cap tip and then translate it to
north_square or south_square. */
if (capmap.region == cap_map<T>::north) {
pole = north_square;
tmpRot = rot[get_rotate_index(capmap.cn - pole)];
} else {
pole = south_square;
tmpRot = rot[get_rotate_index(-1*(capmap.cn - pole))];
}
} else {
/* Inverse function.
Unrotate (xy_x, xy_y) and then translate it back. */
/* disassemble */
if (capmap.region == cap_map<T>::north) {
pole = north_square;
tmpRot = rot[get_rotate_index(-1*(capmap.cn - pole))];
} else {
pole = south_square;
tmpRot = rot[get_rotate_index(capmap.cn - pole)];
}
}
vector_sub(v, c, v_min_c);
dot_product(tmpRot, v_min_c, ret_dot);
{
T a[2];
/* Workaround cppcheck git issue */
T* pa = a;
// TODO: in proj4 5.0.0 this line is used instead
//pa[0] = -3.0*fourth_pi + ((inverse == 0) ? 0 : capmap.cn) *half_pi;
pa[0] = -3.0*fourth_pi + ((inverse == 0) ? pole : capmap.cn) *half_pi;
pa[1] = half_pi;
vector_add(ret_dot, a, vector);
}
xy_x = vector[0];
xy_y = vector[1];
}
