gl-vec3/rotateY.js

gl-matrix's vec3, split into smaller pieces

module.exports = rotateY;

/**
 * Rotate a 3D vector around the y-axis
 * @param {vec3} out The receiving vec3
 * @param {vec3} a The vec3 point to rotate
 * @param {vec3} b The origin of the rotation
 * @param {Number} c The angle of rotation
 * @returns {vec3} out
 */
function rotateY(out, a, b, c){
    var bx = b[0]
    var bz = b[2]

    // translate point to the origin
    var px = a[0] - bx
    var pz = a[2] - bz
    
    var sc = Math.sin(c)
    var cc = Math.cos(c)
  
    // perform rotation and translate to correct position
    out[0] = bx + pz * sc + px * cc
    out[1] = a[1]
    out[2] = bz + pz * cc - px * sc
  
    return out
}