Need help about triangulation set of points with constrained edges

[roadcad]

Hello.

I am trying to triangulate set of points with constraint edges but could not to figure out how to do this with Triangle.net.

So, I hope that this is possible to do with this great library. It's attached example done in other software.

Thank you.

[wo80]

Use a Polygon and add the points and segments. Then use the polygon.Triangulate() method to create the mesh.

Take a look at https://github.com/wo80/Triangle.NET/wiki/Polygon#using-segments and let me know, if anything is unclear.

[roadcad]

Use a Polygon and add the points and segments. Then use the polygon.Triangulate() method to create the mesh.

Take a look at https://github.com/wo80/Triangle.NET/wiki/Polygon#using-segments and let me know, if anything is unclear.

Thank you for quick response.

I tested code from link which you provide, and it works well. I am little confused with outher and inner box from your example. Actually, in my example you can see set of arbitrary points and one polyline (set of lines) inside that polygon - not outher or inner box. This is one example, but it is possible that be more that one set of lines (polyline).

[wo80]

Here's another simple example:

using TriangleNet.Geometry;
using TriangleNet.Meshing;
using TriangleNet.Rendering.Text;

class Issue34
{
    public static void Run()
    {
        var poly = new Polygon();

        // The input point set.
        var points = new Vertex[]
        {
            new Vertex(0d, 0d),
            new Vertex(1d, 0d),
            new Vertex(1d, 1d),
            new Vertex(0d, 1d),

            // These vertices are endpoints of segments.
            new Vertex(.2d, .2d),
            new Vertex(.4d, .6d),
            new Vertex(.8d, .8d)
        };

        // Add all points at once.
        poly.Points.AddRange(points);

        // Now add segments. This is just a simple example. There are other
        // poly.Add(segment, ...) overloads that might be better suited for
        // your setup.
        poly.Add(new Segment(points[4], points[5]));
        poly.Add(new Segment(points[5], points[6]));

        // IMPORTANT: use convex option. Otherwise all triangles will be eaten
        // up since your input polygon has no outer boundary.
        var mesh = poly.Triangulate(new ConstraintOptions() { Convex = true });

        SvgImage.Save(mesh, "issue34.svg", 500, points: false);
    }
}

[wo80]

Note that setting up the geometry this way, you'll have to deal with vertices and segments. There's no concept of lines / line strings in Triangle.NET.

You might also want to take a look at the following example: https://gist.github.com/wo80/fe9b40925cdfdafedad935457c4768dd

It introduces a Constraint helper class and an extension method to simplify adding line strings to a polygon.

[roadcad]

@wo80 Thank you very much for your help, second example explains everything and now it works very well.