Camera constructor
Implementation
Camera({
double zoom = 1,
required double viewportWidth,
required double viewportHeight,
}) : assert(zoom != 0, "zoom cannot be 0"),
assert(viewportWidth > 0, "viewportWidth cannot be 0 or lower"),
assert(viewportHeight > 0, "viewportHeight cannot be 0 or lower"),
_zoom = zoom,
_viewportWidth = viewportWidth,
_viewportHeight = viewportHeight,
id = _idCounter++;