Element input with mouse pointer locked

Right now when the mouse pointer is locked you aren't really able to receive input in world placed UI elements (e.g. 3D screens with buttons).

It would be cool to support this one way or another, interface elements placed in world screens are quite a thing in many first person games.

One easy way for developers to approach this, is by using an internal/private method from the pc.ElementInput class. Example code:

this.app.mouse.on("mouseup", function (e) {

    // --- if pointer is locked we handle our own element input
    if(pc.Mouse.isPointerLocked() === true & e.button === pc.MOUSEBUTTON_LEFT){

        const centerX = this.app.graphicsDevice.canvas.width / 2;
        const centerY = this.app.graphicsDevice.canvas.height / 2;

        const target = this.app.elementInput._getTargetElement(this.entity.camera, centerX, centerY);

        if(target) target.fire('click');
    }
}, this);  

Basically this is a feature request to expose the _getTargetElement method as public API, unless there is formal support for this feature to be discussed.

Start with the pc.ElementInput class and its _getTargetElement method, then inspect how pointer-lock input and world-placed UI elements are currently handled. Decide whether exposing that method or adding formal pointer-lock support fits the existing API; done means developers can receive input from world UI while the pointer is locked through supported engine behavior.