public static ConvexArea convexPolygonFromPath()

in commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/twod/ConvexArea.java [221:271]
34 lines of code
7 McCabe index (conditional complexity)

    public static ConvexArea convexPolygonFromPath(final LinePath path) {
        // ensure that the path is closed; this also ensures that we do not have any infinite elements
        if (!path.isClosed()) {
            throw new IllegalArgumentException("Cannot construct convex polygon from unclosed path: " + path);
        }

        final List<LineConvexSubset> elements = path.getElements();
        if (elements.size() < 3) {
            throw new IllegalArgumentException(
                    "Cannot construct convex polygon from path with less than 3 elements: " + path);
        }

        // go through the elements and validate that the produced area is convex and finite
        // using the precision context from the first path element
        final LineConvexSubset startElement = elements.get(0);
        final Vector2D startVertex = startElement.getStartPoint();
        final Precision.DoubleEquivalence precision = startElement.getPrecision();

        Vector2D curVector;
        Vector2D prevVector = null;

        double signedArea;
        double totalSignedArea = 0.0;

        LineConvexSubset element;

        // we can skip the last element since the we know that the path is closed, meaning that the
        // last element's end point is equal to our start point
        for (int i = 0; i < elements.size() - 1; ++i) {
            element = elements.get(i);

            curVector = startVertex.vectorTo(element.getEndPoint());

            if (prevVector != null) {
                signedArea = prevVector.signedArea(curVector);
                if (precision.lt(signedArea, 0.0)) {
                    throw new IllegalArgumentException(NON_CONVEX_PATH_ERROR + path);
                }

                totalSignedArea += signedArea;
            }

            prevVector = curVector;
        }

        if (precision.lte(totalSignedArea, 0.0)) {
            throw new IllegalArgumentException(NON_CONVEX_PATH_ERROR + path);
        }

        return new ConvexArea(elements);
    }