double
RasterProjection::FinePixelDistance(const GeoPoint &location,
unsigned pixels) const
{
enum {
/**
* This factor is used to reduce fixed point rounding errors.
* x_scale and y_scale are quite large numbers, and building their
* reciprocals may lose a lot of precision.
*/
FACTOR = 256,
};
// must have called Set() first otherwise this is invalid
assert(x_scale != 0);
assert(y_scale != 0);
Angle distance = WidthToAngle(M_SQRT2 * FACTOR * pixels);
GeoPoint p = GeoPoint(location.longitude + distance, location.latitude);
auto x = location.DistanceS(p);
distance = HeightToAngle(M_SQRT2 * FACTOR * pixels);
p = GeoPoint(location.longitude, location.latitude + distance);
auto y = location.DistanceS(p);
return std::max(x, y) / FACTOR;
}
gcc_pure
GeoPoint
UnprojectFine(const RasterLocation &coords) const {
const Angle x = WidthToAngle(fixed((int)coords.x + left));
const Angle y = HeightToAngle(fixed(top - (int)coords.y));
return GeoPoint(x, y);
}
fixed
RasterProjection::FinePixelDistance(const GeoPoint &location,
unsigned pixels) const
{
enum {
/**
* This factor is used to reduce fixed point rounding errors.
* x_scale and y_scale are quite large numbers, and building their
* reciprocals may lose a lot of precision.
*/
FACTOR = 256,
};
Angle distance = WidthToAngle(fixed_sqrt_two * FACTOR * pixels);
GeoPoint p = GeoPoint(location.longitude + distance, location.latitude);
fixed x = location.Distance(p);
distance = HeightToAngle(fixed_sqrt_two * FACTOR * pixels);
p = GeoPoint(location.longitude, location.latitude + distance);
fixed y = location.Distance(p);
return std::max(x, y) / FACTOR;
}
