Method _getLocalAxes

src/webgl/p5.Camera.js:1824–1874

* Returns a camera's local axes: left-right, up-down, and forward-backward, * as defined by vectors in world-space. * @private

()

   * @private
   */
  _getLocalAxes() {
    // calculate camera local Z vector
    let z0 = this.eyeX - this.centerX;
    let z1 = this.eyeY - this.centerY;
    let z2 = this.eyeZ - this.centerZ;

    // normalize camera local Z vector
    const eyeDist = Math.sqrt(z0 * z0 + z1 * z1 + z2 * z2);
    if (eyeDist !== 0) {
      z0 /= eyeDist;
      z1 /= eyeDist;
      z2 /= eyeDist;
    }

    // calculate camera Y vector
    let y0 = this.upX;
    let y1 = this.upY;
    let y2 = this.upZ;

    // compute camera local X vector as up vector (local Y) cross local Z
    let x0 = y1 * z2 - y2 * z1;
    let x1 = -y0 * z2 + y2 * z0;
    let x2 = y0 * z1 - y1 * z0;

    // recompute y = z cross x
    y0 = z1 * x2 - z2 * x1;
    y1 = -z0 * x2 + z2 * x0;
    y2 = z0 * x1 - z1 * x0;

    // cross product gives area of parallelogram, which is < 1.0 for
    // non-perpendicular unit-length vectors; so normalize x, y here:
    const xmag = Math.sqrt(x0 * x0 + x1 * x1 + x2 * x2);
    if (xmag !== 0) {
      x0 /= xmag;
      x1 /= xmag;
      x2 /= xmag;
    }

    const ymag = Math.sqrt(y0 * y0 + y1 * y1 + y2 * y2);
    if (ymag !== 0) {
      y0 /= ymag;
      y1 /= ymag;
      y2 /= ymag;
    }

    return {
      x: [x0, x1, x2],
      y: [y0, y1, y2],
      z: [z0, z1, z2]
    };
  }

  /**
   * Orbits the camera about center point. For use with orbitControl().