Animated "raytraced" sphere in unicode Braille (run in console)

// WARNING edit: this has no framerate limit and will genuinely draw a lot of electrical power.
// press CTRL+C to stop animation! (or just close window)
// if you get question marks in boxes, you may need to run it in smth like Git Bash
w = 52; // If the sphere looks squished on your screen, change width and height here
h = 27;
iter = 2000; // increase iter to slow down animation, decrease to speed up
dot = (u, v) => u.reduce((a, x, i)=>a + x*v[i], 0);
PI = Math.PI;
f = "⠈⠑⠋⠛⠽⠿".split("");
for(;;){
    for(i=0; i < iter; i++){
        S=[];
        v = [-1/2, Math.cos(2*PI*i/iter), Math.sin(2*PI*i/iter)];
        v = v.map(x => x/dot(v,v));
        for(y = 0; y < h; y++){
            for(x = 0; x < w; x++){
                [p, t] = [x/w, y/h].map(e => e*PI/2 + PI/4);
                [x1, y1, z1] = [0, 0, -1.6];
                [x2, y2, z2] = [Math.sin(p)*Math.cos(t), Math.cos(p), Math.sin(p)*Math.sin(t)];
                a = x2*x2 + y2*y2 + z2*z2;
                b = -2*(-x1*x2 - y1*y2 - z1*z2);
                c = x1*x1 + y1*y1 + z1*z1-1;
                d = b*b - 4*a*c;
                if(d >= 0) {
                    u = (-b + Math.sqrt(d))/2/a;
                    n = [x1 + x2*u, y1 + y2*u, z1 + z2*u];
                    r = Math.acos(dot(n,v));
                    S.push(f[Math.floor(r*6/PI)]);
                }
                else S.push("⠀");
            }
            S.push("\n");
        }
        console.log(S.join(""));
    }
}