_initViewMatrix()

in modules/core/src/viewports/viewport.js [300:362]

• 45 lines of code
• 11 McCabe index (conditional complexity)

  _initViewMatrix(opts) {
    const {
      // view matrix
      viewMatrix = IDENTITY,

      longitude = null, // Anchor: lng lat zoom makes viewport work w/ geospatial coordinate systems
      latitude = null,
      zoom = null,

      position = null, // Anchor position offset (in meters for geospatial viewports)
      modelMatrix = null, // A model matrix to be applied to position, to match the layer props API
      focalDistance = 1, // Only needed for orthographic views

      distanceScales = null
    } = opts;

    // Check if we have a geospatial anchor
    this.isGeospatial = Number.isFinite(latitude) && Number.isFinite(longitude);

    this.zoom = zoom;
    if (!Number.isFinite(this.zoom)) {
      this.zoom = this.isGeospatial
        ? getMeterZoom({latitude}) + Math.log2(focalDistance)
        : DEFAULT_ZOOM;
    }
    const scale = Math.pow(2, this.zoom);
    this.scale = scale;

    // Calculate distance scales if lng/lat/zoom are provided
    this.distanceScales = this.isGeospatial
      ? getDistanceScales({latitude, longitude})
      : distanceScales || DEFAULT_DISTANCE_SCALES;

    this.focalDistance = focalDistance;

    this.distanceScales.metersPerUnit = new Vector3(this.distanceScales.metersPerUnit);
    this.distanceScales.unitsPerMeter = new Vector3(this.distanceScales.unitsPerMeter);

    this.position = ZERO_VECTOR;
    this.meterOffset = ZERO_VECTOR;
    if (position) {
      // Apply model matrix if supplied
      this.position = position;
      this.modelMatrix = modelMatrix;
      this.meterOffset = modelMatrix ? modelMatrix.transformVector(position) : position;
    }

    if (this.isGeospatial) {
      // Determine camera center
      this.longitude = longitude;
      this.latitude = latitude;
      this.center = this._getCenterInWorld({longitude, latitude});
    } else {
      this.center = position ? this.projectPosition(position) : [0, 0, 0];
    }
    this.viewMatrixUncentered = viewMatrix;
    // Make a centered version of the matrix for projection modes without an offset
    this.viewMatrix = new Matrix4()
      // Apply the uncentered view matrix
      .multiplyRight(this.viewMatrixUncentered)
      // And center it
      .translate(new Vector3(this.center || ZERO_VECTOR).negate());
  }