function distance(a, b) {
	    var dx = a[0] - b[0];
	    var dy = a[1] - b[1];
	    var dz = a[2] - b[2];
	    return Math.sqrt(dx * dx + dy * dy + dz * dz);
	  }
Computes the distance between 2 points
@param {module:twgl/v3.Vec3} a vector.
@param {module:twgl/v3.Vec3} b vector.
@return {number} distance between a and b
@memberOf module:twgl/v3