code: function processCamera(camera) {
        if (!outputJSON.cameras) {
          outputJSON.cameras = [];
        }
  
        var isOrtho = camera.isOrthographicCamera;
  
        var gltfCamera = {
          type: isOrtho ? 'orthographic' : 'perspective'
        };
  
        if (isOrtho) {
          gltfCamera.orthographic = {
            xmag: camera.right * 2,
            ymag: camera.top * 2,
            zfar: camera.far <= 0 ? 0.001 : camera.far,
            znear: camera.near < 0 ? 0 : camera.near
          };
        } else {
          gltfCamera.perspective = {
            aspectRatio: camera.aspect,
            yfov: THREE.Math.degToRad(camera.fov) / camera.aspect,
            zfar: camera.far <= 0 ? 0.001 : camera.far,
            znear: camera.near < 0 ? 0 : camera.near
          };
        }
  
        if (camera.name !== '') {
          gltfCamera.name = camera.type;
        }
  
        outputJSON.cameras.push(gltfCamera);
  
        return outputJSON.cameras.length - 1;
      }
docs: Process camera
  @param  {THREE.Camera} camera Camera to process
  @return {Integer}      Index of the processed mesh in the "camera" array