Function transformPolygon

docs/app/js/sanddance-app.js:130768–130770

(coordinates)

function transform(grid, sx, sy, tx, ty) {
    const x1 = grid.x1 || 0, y1 = grid.y1 || 0, flip = sx * sy < 0;
    function transformPolygon(coordinates) {
        coordinates.forEach(transformRing);
    }
    function transformRing(coordinates) {
        if (flip) coordinates.reverse(); // maintain winding order
        coordinates.forEach(transformPoint);