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#import "MGLGeometry_Private.h"
#import <mbgl/util/projection.hpp>
/** Vertical field of view, measured in degrees, for determining the altitude
of the viewpoint.
TransformState::getProjMatrix() assumes a vertical field of view of
2 arctan ⅓ rad ≈ 36.9°, but MapKit uses a vertical field of view of 30°.
flyTo() assumes a field of view of 2 arctan ½ rad. */
const CLLocationDegrees MGLAngularFieldOfView = 30;
const MGLCoordinateSpan MGLCoordinateSpanZero = {0, 0};
CGRect MGLExtendRect(CGRect rect, CGPoint point) {
if (point.x < rect.origin.x) {
rect.size.width += rect.origin.x - point.x;
rect.origin.x = point.x;
}
if (point.x > rect.origin.x + rect.size.width) {
rect.size.width += point.x - (rect.origin.x + rect.size.width);
}
if (point.y < rect.origin.y) {
rect.size.height += rect.origin.y - point.y;
rect.origin.y = point.y;
}
if (point.y > rect.origin.y + rect.size.height) {
rect.size.height += point.y - (rect.origin.y + rect.size.height);
}
return rect;
}
CLLocationDistance MGLAltitudeForZoomLevel(double zoomLevel, CGFloat pitch, CLLocationDegrees latitude, CGSize size) {
CLLocationDistance metersPerPixel = mbgl::Projection::getMetersPerPixelAtLatitude(latitude, zoomLevel);
CLLocationDistance metersTall = metersPerPixel * size.height;
CLLocationDistance altitude = metersTall / 2 / std::tan(MGLRadiansFromDegrees(MGLAngularFieldOfView) / 2.);
return altitude * std::sin(M_PI_2 - MGLRadiansFromDegrees(pitch)) / std::sin(M_PI_2);
}
double MGLZoomLevelForAltitude(CLLocationDistance altitude, CGFloat pitch, CLLocationDegrees latitude, CGSize size) {
CLLocationDistance eyeAltitude = altitude / std::sin(M_PI_2 - MGLRadiansFromDegrees(pitch)) * std::sin(M_PI_2);
CLLocationDistance metersTall = eyeAltitude * 2 * std::tan(MGLRadiansFromDegrees(MGLAngularFieldOfView) / 2.);
CLLocationDistance metersPerPixel = metersTall / size.height;
CGFloat mapPixelWidthAtZoom = std::cos(MGLRadiansFromDegrees(latitude)) * mbgl::util::M2PI * mbgl::util::EARTH_RADIUS_M / metersPerPixel;
return ::log2(mapPixelWidthAtZoom / mbgl::util::tileSize);
}
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