orthographic camera projection

[aphex-]

Hello.
I have a virtual orthographic camera that has the following rotation:

rotation = {  x: 55.3,  y: 0,  z: 45 } // degrees

I would like to project screen coordinated to camera space coordinates. ``

const cameraPoint = camera.project(screenPoint);
const screenPoint2 = camera.inverse(cameraPoint);
// expecting screenPoint == screenPoint2

How can I create such a camera and how do I project my coordinates back and forth? Thank you! :)