fitPlaneToScreen

/*
taken from:  https://gist.github.com/ayamflow/96a1f554c3f88eef2f9d0024fc42940f

// Basically solving an AAS triangle https://www.mathsisfun.com/algebra/trig-solving-aas-triangles.html
https://i.stack.imgur.com/PgSn3.jpg
*/

// return height and width of plane that covers viewport at the given plane z position
export default (camera, planeZ, viewWidth, viewHeight) => {
    const cameraZ = camera.position.z;
    const distance = cameraZ - planeZ;
    const aspect = viewWidth / viewHeight;
    const vFov = (camera.fov * Math.PI) / 180;
    const height = 2 * Math.tan(vFov / 2) * distance;
    const width = height * aspect;

    return {
        width,
        height
    };
};