foreach (i, c; ['0', '1', '2', '3']) {
	GLViewport(`view`~c).renderingHandler = &views[i].draw;

	auto ctrl = ViewportControls(`view`~c~`ctrl`);
	views[i].coordSys.origin = vec3fi[ctrl.x, ctrl.y, ctrl.z];
	views[i].zoom = ctrl.zoom;
}