## PolygonFace.TriangleSubIndexArray

### Introduced

v5.0

### Description

Returns a 1-dimensional packed Array of triangulation descriptions corresponding to the tesselation of the polygon. The polygon is tesselated into (NbPoints - 2) triangles, and 3 indices in the range (0..NbPoints-1) are returned for each triangle. Each index triplet describes a subtriangle of the polygon, and the indices correspond to the vertex or node ordering within the polygon.
Notice that the triangulation of a polygon may change accordingly to the deformation of the geometry.

### C# Syntax

    // get accessor
    Object rtn = PolygonFace.TriangleSubIndexArray;

### Examples

#### JScript Example

    /*
            This example demonstrates how to describe the triangulation of some polygons.
    */
    NewScene( null, false );
    var SphereGeom = Application.ActiveSceneRoot.AddGeometry("Sphere", "MeshSurface").ActivePrimitive.Geometry;
    var Polygons = SphereGeom.Polygons;
    for(i = 0; i < Polygons.Count; i++)
    {
            var Polygon = Polygons.Item(i);
            var NbTriangles = Polygon.NbPoints-2;
            var PolygonVertices = Polygon.Vertices;
            var PolygonNodes = Polygon.Nodes;
            var TriangleSubIndices = Polygon.TriangleSubIndexArray.toArray();
            for(j = 0; j < NbTriangles; j++)
            {
                    Application.LogMessage("SubTriangle " + j + " of Polygon " + i + " correspond to vertices (" +
                            PolygonVertices.Item(TriangleSubIndices[j*3]).Index + ", " +
                            PolygonVertices.Item(TriangleSubIndices[j*3+1]).Index + ", " +
                            PolygonVertices.Item(TriangleSubIndices[j*3+2]).Index + ") and nodes (" +
                            PolygonNodes.Item(TriangleSubIndices[j*3]).Index + ", " +
                            PolygonNodes.Item(TriangleSubIndices[j*3+1]).Index + ", " +
                            PolygonNodes.Item(TriangleSubIndices[j*3+2]).Index + ").");
            }
    }
    // Expected results:
    //INFO : SubTriangle 0 of Polygon 0 correspond to vertices (9, 2, 0) and nodes (0, 1, 2).
    //INFO : SubTriangle 0 of Polygon 1 correspond to vertices (2, 9, 10) and nodes (3, 4, 5).
    //INFO : SubTriangle 1 of Polygon 1 correspond to vertices (2, 10, 3) and nodes (3, 5, 6).
    //INFO : SubTriangle 0 of Polygon 2 correspond to vertices (3, 10, 11) and nodes (7, 8, 9).
    //INFO : SubTriangle 1 of Polygon 2 correspond to vertices (3, 11, 4) and nodes (7, 9, 10).
    //etc.

### See Also

PolygonFace.Vertices PolygonFace.Nodes