//
//      This example creates point locators at random surface locations,
//      and positions a Null at each of these point locators.
//      
//      Even if these point locators are simply randomly constructed,
//      this example shows how to do it in the most accurate way,
//      which is to specify subtriangles which correspond to the actual
//      polygon triangulation.
//
NewScene( null, false );
var SphereGeom = CreatePrim("Sphere", "MeshSurface").ActivePrimitive.Geometry;
var NbPtLocators = 50;
var PolygonIndexArray = new Array(NbPtLocators);
var SubTriangleVertexArray = new Array(NbPtLocators*3);
var SubTriangleWeightArray = new Array(NbPtLocators*3);
var Polygons = SphereGeom.Polygons;
for(i = 0; i < NbPtLocators; i++) {
        PolygonIndexArray[i] = Math.floor(Math.random() * 0.999999 * Polygons.Count);
        var Polygon = Polygons.Item(PolygonIndexArray[i]);
        var SubTri = Math.floor(Math.random() * 0.999999 * (Polygon.NbPoints-2));
        var PolygonVertices = Polygon.Vertices;
        var TriangleSubIndices = Polygon.TriangleSubIndexArray.toArray();
        SubTriangleVertexArray[i*3] = PolygonVertices.Item(TriangleSubIndices[SubTri*3]).Index;
        SubTriangleVertexArray[i*3+1] = PolygonVertices.Item(TriangleSubIndices[SubTri*3+1]).Index;
        SubTriangleVertexArray[i*3+2] = PolygonVertices.Item(TriangleSubIndices[SubTri*3+2]).Index;
        var W1 = Math.random();
        var W2 = Math.random();
        var W3 = Math.random();
        var WSum = W1+W2+W3;
        SubTriangleWeightArray[i*3] = W1/WSum;
        SubTriangleWeightArray[i*3+1] = W2/WSum;
        SubTriangleWeightArray[i*3+2] = W3/WSum;
}
var RandomPointLocators = SphereGeom.ConstructPointLocators(PolygonIndexArray, SubTriangleVertexArray, SubTriangleWeightArray);
CreateNullsAtPointLocations(SphereGeom, RandomPointLocators);
function CreateNullsAtPointLocations( InGeom, InPointLocators )
{
        var SpherePositions = InGeom.EvaluatePositions(InPointLocators).toArray();
        var SphereNormals = InGeom.EvaluateNormals(InPointLocators).toArray();
        var TempVector = XSIMath.CreateVector3();
        var TempRotation = XSIMath.CreateRotation();
        for (i = 0; i < SpherePositions.length; i+=3)
        {
                var NullObj = GetPrim( "Null" );
                TempVector.Set(SpherePositions[i], SpherePositions[i+1], SpherePositions[i+2]);
                NullObj.LocalTranslation = TempVector;
                TempVector.Set(SphereNormals[i], SphereNormals[i+1], SphereNormals[i+2]);
                TempRotation.SetFromXYZAxes( TempVector, TempVector, TempVector );
                NullObj.LocalRotation = TempRotation;
        }
}