export function getOffsetOrigin()

in modules/core/src/shaderlib/project/viewport-uniforms.js [40:105]
54 lines of code
13 McCabe index (conditional complexity)

export function getOffsetOrigin(
  viewport,
  coordinateSystem,
  coordinateOrigin = DEFAULT_COORDINATE_ORIGIN
) {
  let shaderCoordinateOrigin = coordinateOrigin;
  let geospatialOrigin;
  let offsetMode = true;

  if (
    coordinateSystem === COORDINATE_SYSTEM.LNGLAT_OFFSETS ||
    coordinateSystem === COORDINATE_SYSTEM.METER_OFFSETS
  ) {
    geospatialOrigin = coordinateOrigin;
  } else {
    geospatialOrigin = viewport.isGeospatial
      ? [Math.fround(viewport.longitude), Math.fround(viewport.latitude), 0]
      : null;
  }

  switch (viewport.projectionMode) {
    case PROJECTION_MODE.WEB_MERCATOR:
      if (
        coordinateSystem === COORDINATE_SYSTEM.LNGLAT ||
        coordinateSystem === COORDINATE_SYSTEM.CARTESIAN
      ) {
        offsetMode = false;
      }
      break;

    case PROJECTION_MODE.WEB_MERCATOR_AUTO_OFFSET:
      if (coordinateSystem === COORDINATE_SYSTEM.LNGLAT) {
        // viewport center in world space
        shaderCoordinateOrigin = geospatialOrigin;
      } else if (coordinateSystem === COORDINATE_SYSTEM.CARTESIAN) {
        // viewport center in common space
        shaderCoordinateOrigin = [
          Math.fround(viewport.center[0]),
          Math.fround(viewport.center[1]),
          0
        ];
        // Geospatial origin (wgs84) must match shaderCoordinateOrigin (common)
        geospatialOrigin = viewport.unprojectPosition(shaderCoordinateOrigin);
        shaderCoordinateOrigin[0] -= coordinateOrigin[0];
        shaderCoordinateOrigin[1] -= coordinateOrigin[1];
        shaderCoordinateOrigin[2] -= coordinateOrigin[2];
      }
      break;

    case PROJECTION_MODE.IDENTITY:
      shaderCoordinateOrigin = viewport.position.map(Math.fround);
      break;

    case PROJECTION_MODE.GLOBE:
      offsetMode = false;
      break;

    default:
      // Unknown projection mode
      offsetMode = false;
  }

  shaderCoordinateOrigin[2] = shaderCoordinateOrigin[2] || 0;

  return {geospatialOrigin, shaderCoordinateOrigin, offsetMode};
}