how can I select a Object (Children) in view?

With mauseclick...

Hi! I'm using CuttingEarsTriangulator to draw complex polygons.
It works almost all the time but I found some cases in which method Triangulate gives me null even if the polygons is valid.

One of this cases is when I pass the following list of points:
0,0
0,1.894
-2.536,1.42
-5.072,1.42
-5.072,2.84
-10.144,2.84
-10.144,0

How can I get my triangles? Is there a workaround?

I haven't studied the code in the Helix stack, but I've gotten very good Cutting Ear results from the archived CodeProject project at:

http://www.codeproject.com/Articles/8238/Polygon-Triangulation-in-C

The code is conveniently in C# and contains no dependencies on anything except .NET (probably .NET 1.1, so it would be good for any .NET stack)

baucez: thanks for the example polygon - I will add a unit test for this case
RobPerkins: thanks for the link, I will have a look at that implementation, and possible use it to verify results

the following code

           var polygon = new[]
                              {
                                  new Point(0, 0),
                                  new Point(0, 1.894),
                                  new Point(-2.536, 1.42),
                                  new Point(-5.072, 1.42),
                                  new Point(-5.072, 2.84),
                                  new Point(-10.144, 2.84),
                                  new Point(-10.144, 0)
                              };
            var result = CuttingEarsTriangulator.Triangulate(polygon);

gives the result

{0 1 2 3 4 5 6 0 2 3 5 6 6 2 3}

which looks correct to me...

Objo.. you are right!
I looked better at my code and I found that the list of points that I gave you was approximated.

If you try this code will fail:

  {
            var polygon = new[]
                {
                    new Point(0, 0),
                    new Point(0, 2.97),
                    new Point(-2.389999999999997, 2.97),
                    new Point(-2.389999999999997, 1.4849999999999999),
                    new Point(-4.7799999999999976, 1.4849999999999999),
                    new Point(-4.7799999999999976, 2.97),
                    new Point(-9.5599999999999987, 2.97),
                    new Point(-9.5599999999999987, 0),
                };

            var result = CuttingEarsTriangulator.Triangulate(polygon);
            Assert.IsNotNull(result);
        }

The problem is caused by double arithmetic approximations.
In particular (but I'm not sure is the only place in the code) the problem is in the comparisons at the end of CuttingEarsTriangulator.InsideTriangle method

thanks! I have checked in the fix

Hi
I started to add position and normal and texture coordinates to a meshbuilder but i get memory inefficient by debuger!
Is it a memory leak? How can i handle this?

Please provide an example that shows the problem! The MeshBuilder should not hold any memory.

I found that my problem is about exceeding memory for an array not meshbuilder thank you

What is the concept For merging two meshgeometry3D ?
Is there anything in this library for it?

The MeshBuilder.Append method can do this!

Hi,
I don't know how to change the opacity of an FileModelVisual3D object.
Somebody can help me...

Try to traverse the visual tree below the FileModelVisual3D and replace the materials in the GeometryModel3D objects.

thanks for your answer but I don't know how 'to traverse the visual tree'...
I can access to children of viewport but after... I don't know...

Hi,
Anybody knows how to retrieve geometryModel3D from FileModelVisual3D ?

I've never worked with FileModelVisual3D but I'm sure that the way is to try to cast its Content as GeometryModel3D and Model3DGroup:

   Model3DGroup grupo = (Model3DGroup)myFileModelVisual3D.Content;

            foreach (var modelo in grupo.Children.OfType<GeometryModel3D>())
            {
                GeometryModel3D model = (GeometryModel3D)modelo;
                var mat1 = modelo.Material.Clone();
                var mat2 = modelo.BackMaterial.Clone();
                MaterialHelper.ChangeOpacity(mat1, SliderVerifyOpacity.Value);
                MaterialHelper.ChangeOpacity(mat2, SliderVerifyOpacity.Value);

                model.Material = mat1;
                model.BackMaterial = mat2;
            }

            foreach (var group in grupo.Children.OfType<Model3DGroup>())
            {
                Model3DGroup grupoModel = (Model3DGroup)group;
                foreach (var modelo in grupoModel.Children.OfType<GeometryModel3D>())
                {
                    GeometryModel3D model = (GeometryModel3D)modelo;

                    var mat1 = modelo.Material.Clone();
                    var mat2 = modelo.BackMaterial.Clone();
                    MaterialHelper.ChangeOpacity(mat1, SliderVerifyOpacity.Value);
                    MaterialHelper.ChangeOpacity(mat2, SliderVerifyOpacity.Value);

                    model.Material = mat1;
                    model.BackMaterial = mat2;
                }
            }

In this example the opacity is controlled by a Slider, change to a specific value if you want it so.
Good luck.

How can I make 2D polygon geometry with image texture.

For the rectangle I use two triangle and for texture I added coordinates for triangles:

// triangle ABC
mesh.TriangleIndices.Add(0);
mesh.TriangleIndices.Add(1);
mesh.TriangleIndices.Add(2);

// triangle ACD
mesh.TriangleIndices.Add(0);
mesh.TriangleIndices.Add(2);
mesh.TriangleIndices.Add(3);

mesh.TextureCoordinates.Add(new Point(0, 1)); // point A
mesh.TextureCoordinates.Add(new Point(1, 1)); // point B
mesh.TextureCoordinates.Add(new Point(1, 0)); // point C
mesh.TextureCoordinates.Add(new Point(0, 0)); // point D


var d = new DiffuseMaterial(imgBrush);
mGeometries.Add(new GeometryModel3D(mesh, d));

....


On this discussion I found functions for create of polygon.
public static MeshGeometry3D FillPolygon(Polygon p)

    {
        List<Point3D> pts3D = new List<Point3D>();
        foreach (var point in p.Points)
        {
            pts3D.Add(new Point3D(point.X, point.Y, 0));
        }
        Polygon3D p3 = new Polygon3D(pts3D);
        return FillPolygon(p3);
    }

    public static MeshGeometry3D FillPolygon(Polygon3D p3)
    {
        var meshBuilder = new MeshBuilder(false, false);

        Polygon polygon = p3.Flatten();
        var triangleIndexes = CuttingEarsTriangulator.Triangulate(polygon.Points);

        meshBuilder.Append(p3.Points, triangleIndexes);

        return meshBuilder.ToMesh();
    }

Polygon drawing right, but I do not know how I do configuration for fill texture on the polygon.
Texture is rectangle image and I wants show shape cut of texture on the polygon.

Thank you very much.
Jindrich