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From "Andrew Willis (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MATH-780) BSPTree class and recovery of a Euclidean 3D BRep
Date Fri, 20 Apr 2012 15:12:40 GMT
BSPTree class and recovery of a Euclidean 3D BRep
-------------------------------------------------

                 Key: MATH-780
                 URL: https://issues.apache.org/jira/browse/MATH-780
             Project: Commons Math
          Issue Type: Bug
    Affects Versions: 3.0
         Environment: Linux
            Reporter: Andrew Willis


New to the work here. Thanks for your efforts on this code.

I create a BSPTree from a BoundaryRep (Brep) my test Brep is a tetrahedron as represented
by a float array containing 4 3D points (x,y,z) order and an array of indices (4 triplets
for the 4 faces of the tet). I construct a BSPMesh() as shown in the code below. I can construct
the PolyhedronsSet() however, when I interrogate the shape (with getSize() or getBoundarySize()
I get infinity back as a result). When I try to get back the BRep (by traversing the BSPTree
resulting from PolyhedronsSet.getTree(true) and getting the PolygonsSet() associated with
each 3D SubPlane, I get a null vertex back and strange values. 

Any ideas?

public class BSPMesh {

    public BSPMesh(float[] coords, int[] indices) {
        double size;
        setBoundingBox(coords);
        ArrayList<SubHyperplane<Euclidean3D>> subHyperplaneList = new ArrayList();
        for (int idx = 0; idx < indices.length; idx += 3) {
            int idxA = indices[idx] * 3;
            int idxB = indices[idx + 1] * 3;
            int idxC = indices[idx + 2] * 3;
            Vector3D v_1 = new Vector3D(coords[idxA], coords[idxA + 1], coords[idxA + 2]);
            Vector3D v_2 = new Vector3D(coords[idxB], coords[idxB + 1], coords[idxB + 2]);
            Vector3D v_3 = new Vector3D(coords[idxC], coords[idxC + 1], coords[idxC + 2]);
            Vector3D[] vertices = {v_1, v_2, v_3};
            Plane polyPlane = new Plane(v_1, v_2, v_3);
            ArrayList<SubHyperplane<Euclidean2D>> lines = new ArrayList();

            Vector2D[] projPts = new Vector2D[vertices.length];
            for (int ptIdx=0; ptIdx < projPts.length; ptIdx++) {
                projPts[ptIdx] = polyPlane.toSubSpace(vertices[ptIdx]);
            }

            SubLine lineInPlane = null;
            for (int ptIdx=0; ptIdx < projPts.length; ptIdx++) {
                lineInPlane = new SubLine(projPts[ptIdx], projPts[(ptIdx+1)%projPts.length]);
                lines.add(lineInPlane);
            }
            Region<Euclidean2D> polyRegion = new PolygonsSet(lines);
            SubPlane polygon = new SubPlane(polyPlane, polyRegion);
            size = polyRegion.getSize(); // correct size here
            Vector3D[][] verticesTest = getVertices(polygon); // correctly retrieves the BRep
for each face
            subHyperplaneList.add(polygon);
        }
        PolyhedronsSet polyhedronsSet = new PolyhedronsSet(subHyperplaneList);
        BSPTree<Euclidean3D> myTree = polyhedronsSet.getTree(true);
        size = polyhedronsSet.getSize();        // strange Inf returned
        size = polyhedronsSet2.getBoundarySize();         // strange Inf returned
        tree = myTree;
        Vector3D[][] vertices = getVertices((SubPlane) ((BoundaryAttribute) tree.getAttribute()).getPlusOutside());
// strange values returned here
        System.out.println("END");
    }

    public static void main(String[] args) {
            float[] tetCoords = {1, 0, 0,
                2, 0, 0,
                1, 1, 0,
                1, 0, 1};
            int[] tetIndices = {0, 1, 2,
                0, 1, 3,
                0, 2, 3,
                2, 1, 3};
            BSPMesh blah = new BSPMesh(tetCoords, tetIndices);
     }
}



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