[MATH-1450] PolygonsSet sets incorrect value for last vertex in open loops

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0, 3.5, 3.6
• Fix Version/s: 4.0
• Assignee: Unassigned
• Reporter: Matt Juntunen
• Created: 11/Feb/18 04:41
• Updated: 15/Feb/18 18:57
• Resolved: 15/Feb/18 18:57

Description

According to the documentation, for open infinite vertex loops returned by the PolygonsSet.getVertices() method, the last two points can be used to determine the direction of the last edge in the loop. However, the current code returns a point from the second-to-last edge. For example, the code below builds a box open on the top. It currently returns the vertex loop [null, \{0; 1}, \{0; 0}, \{1; 0}, \{1; 0}], where the last two vertices are the same point and cannot be used to determine the direction of the last edge. The returned vertex loop should be [null, \{0; 1}, \{0; 0}, \{1; 0}, \{1; 1}].

Cartesian2D v0 = new Cartesian2D(0, 1);
        Cartesian2D v1 = new Cartesian2D(0, 0);
        Cartesian2D v2 = new Cartesian2D(1, 0);
        Cartesian2D v3 = new Cartesian2D(1, 1);

        Line left = new Line(v0, v1, 1e-10);
        Line bottom = new Line(v1, v2, 1e-10);
        Line right = new Line(v2, v3, 1e-10);

        List<SubHyperplane<Euclidean2D>> boundaries = new ArrayList<>();
        boundaries.add(new SubLine(left, new IntervalsSet(left.toSubSpace(v0).getX(), left.toSubSpace(v1).getX(), 1e-10)));
        boundaries.add(new SubLine(bottom, new IntervalsSet(bottom.toSubSpace(v1).getX(), bottom.toSubSpace(v2).getX(), 1e-10)));
        boundaries.add(new SubLine(right, new IntervalsSet(right.toSubSpace(v2).getX(), right.toSubSpace(v3).getX(), 1e-10)));

        PolygonsSet polygon = new PolygonsSet(boundaries, 1e-10);

        polygon.getVertices();

      

 

Pull Request: https://github.com/apache/commons-math/pull/81