[SOLVED] How do we size something using screen pixels

[trusktr]

I was missing some basics, but since posting my last comment in this thread, I figured out the simple formula after doing some basic geometry with the frustum on paper:

Functions to calculate the visible width / height at a given z-depth from a perspective camera

Aha! After taking a look at this again, I realized that instead of using these functions and a binary search, matching the Three.js perspective to CSS3d perspective boils down to a short equation: const perspective = 800 // this equation const fov = 180 * ( 2 * Math.atan( innerHeight / 2 / perspective ) ) / Math.PI // then align the Three.js perspective with the CSS3D perspective: camera = new THREE.PerspectiveCamera( fov, window.innerWidth / window.innerHeight, 1, 10000 ); camera.position.se…

Its a fun satisfying process.