orbitBy method
Rotates the orbit by deltaAzimuth (around world up) and deltaPolar
(elevation), radians. Polar is clamped to [minPolar, maxPolar].
Implementation
void orbitBy(double deltaAzimuth, double deltaPolar) {
_azimuthGoal += deltaAzimuth;
_polarGoal = (_polarGoal + deltaPolar).clamp(minPolar, maxPolar);
}