javascript - Can someone explain the formula

Question

I have found a formula which does the following:

https://threejs.org/examples/css3d_periodictable.html (the sphere version)

I modified the code a little bit to work with my objects, but changed nothing in the math behind it.

My question is if someone can explain what is exactly happening in the calculation for the position.

This is the code:

for ( var i = 0, l = 30; i < l; i ++ ) {

    var phi = Math.acos( -1 + ( 2 * i ) / l );
    var theta = Math.sqrt( l * Math.PI ) * phi;

    var object = new THREE.Mesh( geometry, material );

    object.position.x = 1000 * Math.cos( theta ) * Math.sin( phi );
    object.position.y = 1000 * Math.sin( theta ) * Math.sin( phi );
    object.position.z = 1000 * Math.cos( phi );

    scene.add(object);

}

I hope someone is able to help me

Thanks in advance

Answer 1

This code is transforming Cartesian coordinates to spherical coordinates. Check this wikipedia entry on coordinate system convertions.

The best way to draw a sphere ;)