How to limit the camera panning

let width = app.renderer.domElement.width;
let height = app.renderer.domElement.height;
let panLimitX = width / 2;
let panLimitY = height / 2;
let movementX, movementY, offsetX, offsetY, prevX, prevY;
const pixelRatio = app.renderer.getPixelRatio();
const isMobileDevice = v3d.Detector.checkAndroid() || v3d.Detector.checkIOS();
const v3dCanvas = app.controls.domElement;
app.camera.setViewOffset(width, height, 0, 0, width, height);

window.addEventListener('resize', function() {
    width = app.renderer.domElement.width;
    height = app.renderer.domElement.height;
    panLimitX = width / 2;
    panLimitY = height / 2;
}, false);

if (isMobileDevice) {
    v3dCanvas.addEventListener('touchstart', function() {
        if (event.touches.length != 2)
            return;
        prevX = event.touches[0].pageX;
        prevY = event.touches[0].pageY;
    }, false);
    v3dCanvas.addEventListener('touchmove', setCamOffsetMobile,  false);
} else {
    v3dCanvas.addEventListener('mousemove', setCamOffsetDesktop,  false);
}

function setCamOffsetDesktop() {
    if (event.which < 2)
        return;
    setCamOffset(event.movementX, event.movementY);
}

function setCamOffsetMobile() {
    if (event.touches.length != 2)
        return;
    movementX = event.touches[0].pageX - prevX;
    movementY = event.touches[0].pageY - prevY;
    prevX = event.touches[0].pageX;
    prevY = event.touches[0].pageY;
    setCamOffset(movementX, movementY);
}

function setCamOffset(moveX, moveY) {
    offsetX = app.camera.view.offsetX - moveX * pixelRatio;
    offsetY = app.camera.view.offsetY - moveY * pixelRatio;
    offsetX = v3d.Math.clamp(offsetX, -panLimitX, panLimitX);
    offsetY = v3d.Math.clamp(offsetY, -panLimitY, panLimitY);
    app.camera.setViewOffset(width, height, offsetX, offsetY, width, height);
}

it’s the problem of FireFox. It can’t read event.which and event.button properly.

Replace if (event.which < 2) with if (event.buttons != 2) and it will work in FireFox too.

P.S. The demo has been updated. Works in the latest FireFox.
https://v3d.net/ajo