int img_sample(img *p, const double *v, float *c)
{
const double lon = tolon(atan2(v[0], v[2])), lat = asin(v[1]);
float klat = 1.f;
float klon = 1.f;
if (p->latc || p->lat0 || p->lat1)
klat = (float) blend(p->lat0, p->lat1, angle(lat, p->latc));
if (p->lonc || p->lon0 || p->lon1)
klon = (float) blend(p->lon0, p->lon1, angle(lon, p->lonc));
float k;
int h = 0;
if ((k = klat * klon))
{
double t[2];
if (p->project(p, v, lon, lat, t))
{
if ((h = img_linear(p, t, c)))
{
switch (p->c)
{
case 4: c[3] *= k;
case 3: c[2] *= k;
case 2: c[1] *= k;
case 1: c[0] *= k;
}
}
}
}
return h;
}
int img_default(img *p, const double *v, double lon, double lat, double *t)
{
t[0] = p->h * (lat - p->minimum_latitude) / ( p->maximum_latitude - p->minimum_latitude);
t[1] = p->w * tolon(lon - p->westernmost_longitude) / (p->easternmost_longitude - p->westernmost_longitude);
return 1;
}
virtual void tolatlon(double l, double s, double& lat, double& lon) const
{
double x;
double y;
toXY(l, s, x, y);
double p = sqrt(x * x + y * y);
double c = atan(radius * p / 2) * 2;
lat = asin(cos(c) * sin(latp) + y * sin(c) * cos(latp) / p);
if (latp > 0)
lon = tolon(lonp + atan2(x, -y));
else
lon = tolon(lonp + atan2(x, y));
}
int img_simple_cylindrical(img *p, const double *v, double lon, double lat, double *t)
{
#if 0
lon = tolon(lon - M_PI);
#endif
t[0] = p->line_projection_offset - p->map_resolution * (todeg(lat) - todeg( p->center_latitude)) - 1; // FIRST_PIXEL
t[1] = p->sample_projection_offset + p->map_resolution * (todeg(lon) - todeg(p->center_longitude)) - 1; // FIRST_PIXEL
return 1;
}
virtual void tolatlon(double l, double s, double& lat, double& lon) const
{
double x;
double y;
toXY(l, s, x, y);
double p = sqrt(x * x + y * y);
double c = asin(p / radius);
lat = asin(cos(c) * sin(latp) + y * sin(c) * cos(latp) / p);
lon = tolon(lonp + atan2(x * sin(c), p * cos(c)));
}
int img_locate(img *p, const double *v)
{
const double lon = tolon(atan2(v[0], v[2])), lat = asin(v[1]);
double t[2];
if (p->project(p, v, lon, lat, t))
{
if (0 <= t[0] && t[0] < p->h && 0 <= t[1] && t[1] < p->w)
{
return 1;
}
return 0;
}
return 0;
}
