Need Help with 3D triangulation for Android

Questions & Answers
1

I just ran into the first big problem with my current Android project.
I want to display a 3d Level that is generated from 2d data. (List of obstacles with defined corner points + a fix height stored in a json file.)
I managed to draw them onto the floor using some code I found online and the triangulation code from the wiki. Now to make them 3d I would have to move the top part (which I already have) up (that is eays :P) and then draw a border/walls around it.

The Problem is that all the triangulation code I found online is 2d only. In order to draw my walls/ borders I need a 3rd axis(up). But whenever I tried to modify my code to add 3d support Unity stopped rendering any triangles at all :frowning:

Would be great If anyone could help me with this.

This is what I currently use:

 private static Mesh CreateMesh(List<Vector3> verts)
    {
        var tris = new Triangulator(verts.Select(x => x.ToVector2xz()).ToArray());
        var mesh = new Mesh();

        var vertices = verts.Select(x => new Vector3(x.x, x.y, x.z)).ToList();
        var indices = tris.Triangulate().ToList();
        //var uv = new List<Vector2>();

        var n = vertices.Count;
        for (int index = 0; index < n; index++)
        {
            var v = vertices[index];
            vertices.Add(new Vector3(v.x, v.y, v.z));
        }

        for (int i = 0; i < n - 1; i++)
        {
            indices.Add(i);
            indices.Add(i + n);
            indices.Add(i + n + 1);
            indices.Add(i);
            indices.Add(i + n + 1);
            indices.Add(i + 1);
        }

        indices.Add(n - 1);
        indices.Add(n);
        indices.Add(0);

        indices.Add(n - 1);
        indices.Add(n + n - 1);
        indices.Add(n);



        mesh.vertices = vertices.ToArray();
        mesh.triangles = indices.ToArray();

        mesh.RecalculateNormals();
        mesh.RecalculateBounds();

        return mesh;
    }
2

Figured it out on my own. Sometimes a cup of hot choclat works wonders…

      private static Mesh CreateMesh(List<Vector3> verts, float height)
        {
            var tris = new Triangulator(verts.Select(x => x.ToVector2xz()).ToArray());
            var mesh = new Mesh();

            var vertices = verts.Select(x => new Vector3(x.x, height, x.z)).ToList();
            var indices = tris.Triangulate().ToList();
            //var uv = new List<Vector2>();

            var numberOfPointsPerRing = vertices.Count;
            for (int index = 0; index < numberOfPointsPerRing; index++)
            {
                var v = vertices[index];
                vertices.Add(new Vector3(v.x, 0, v.z));
            }

            for (int i = 0; i < numberOfPointsPerRing - 1; i++)
            {
                indices.Add(i);
                indices.Add(i + numberOfPointsPerRing);
                indices.Add(i + numberOfPointsPerRing + 1);
                indices.Add(i);
                indices.Add(i + numberOfPointsPerRing + 1);
                indices.Add(i + 1);
            }

            indices.Add(numberOfPointsPerRing - 1);
            indices.Add(numberOfPointsPerRing);
            indices.Add(0);

            indices.Add(numberOfPointsPerRing - 1);
            indices.Add(numberOfPointsPerRing + numberOfPointsPerRing - 1);
            indices.Add(numberOfPointsPerRing);


            //Lower pointposition hinzufügen
            foreach(Vector3 point in verts)
            {
                vertices.Add(new Vector3(point.x, 0, point.z));
            }


            int pointAbove = numberOfPointsPerRing;
            for(int i=0; i<numberOfPointsPerRing; i++)
            {
                //right upper triangle
                indices.Add(i);             //right down
                indices.Add(i+1+pointAbove);//left up
                indices.Add(i+ pointAbove); //right up

                //left lower triangle
                indices.Add(i +1);             //right down
                indices.Add(i + 1 + pointAbove);//left up
                indices.Add(i); //right up

            }



            mesh.vertices = vertices.ToArray();
            mesh.triangles = indices.ToArray();

            mesh.RecalculateNormals();
            mesh.RecalculateBounds();

            return mesh;
        }

    }
}