# Difference between revisions of "Planar Subdivision in CSharp"

This project is part of the Emgu.CV.Example solution

## System Requirement

Component Requirement Detail
Emgu CV Version 1.5
Operation System Cross Platform

## Source Code

### Emgu CV 3.x

Click to view source code

```using System;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.InteropServices;
using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using Emgu.CV.Util;

namespace PlanarSubdivisionExample
{
public static class DrawSubdivision
{
/// <summary>
/// Create planar subdivision for random points
/// </summary>
/// <param name="maxValue">The points contains values between [0, maxValue)</param>
/// <param name="pointCount">The total number of points to create</param>
public static void CreateSubdivision(float maxValue, int pointCount, out Triangle2DF[] delaunayTriangles, out VoronoiFacet[] voronoiFacets)
{
#region create random points in the range of [0, maxValue]
PointF[] pts = new PointF[pointCount];
Random r = new Random((int)(DateTime.Now.Ticks & 0x0000ffff));
for (int i = 0; i < pts.Length; i++)
pts[i] = new PointF((float)r.NextDouble() * maxValue, (float)r.NextDouble() * maxValue);
#endregion

using (Subdiv2D subdivision = new Subdiv2D(pts))
{
//Obtain the delaunay's triangulation from the set of points;
delaunayTriangles = subdivision.GetDelaunayTriangles();

//Obtain the voronoi facets from the set of points
voronoiFacets = subdivision.GetVoronoiFacets();
}
}

/// <summary>
/// Draw the planar subdivision
/// </summary>
/// <param name="maxValue">The points contains values between [0, maxValue)</param>
/// <param name="pointCount">The total number of points</param>
/// <returns>An image representing the planar subvidision of the points</returns>
public static Mat Draw(float maxValue, int pointCount)
{
Triangle2DF[] delaunayTriangles;
VoronoiFacet[] voronoiFacets;
Random r = new Random((int)(DateTime.Now.Ticks & 0x0000ffff));

CreateSubdivision(maxValue, pointCount, out delaunayTriangles, out voronoiFacets);

//create an image for display purpose
Mat img = new Mat((int)maxValue, (int)maxValue, DepthType.Cv8U, 3);

//Draw the voronoi Facets
foreach (VoronoiFacet facet in voronoiFacets)
{
#if NETFX_CORE
Point[] polyline = Extensions.ConvertAll<PointF, Point>(facet.Vertices, Point.Round);
#else
Point[] polyline = Array.ConvertAll<PointF, Point>(facet.Vertices, Point.Round);
#endif
using (VectorOfPoint vp = new VectorOfPoint(polyline))
using (VectorOfVectorOfPoint vvp = new VectorOfVectorOfPoint(vp))
{
//Draw the facet in color
CvInvoke.FillPoly(
img, vvp,
new Bgr(r.NextDouble()*120, r.NextDouble()*120, r.NextDouble()*120).MCvScalar);

//highlight the edge of the facet in black
CvInvoke.Polylines(img, vp, true, new Bgr(0, 0, 0).MCvScalar, 2);
}
//draw the points associated with each facet in red
CvInvoke.Circle(img, Point.Round( facet.Point ), 5, new Bgr(0, 0, 255).MCvScalar, -1);
}

//Draw the Delaunay triangulation
foreach (Triangle2DF triangle in delaunayTriangles)
{
#if NETFX_CORE
Point[] vertices = Extensions.ConvertAll<PointF, Point>(triangle.GetVertices(), Point.Round);
#else
Point[] vertices = Array.ConvertAll<PointF, Point>(triangle.GetVertices(), Point.Round);
#endif
using (VectorOfPoint vp = new VectorOfPoint(vertices))
{
CvInvoke.Polylines(img, vp, true, new Bgr(255, 255, 255).MCvScalar);
}
}

return img;
}
}
}
```

### Emgu CV 2.x

Click to view source code

```using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Drawing;
using Emgu.CV;
using Emgu.CV.UI;
using Emgu.CV.Structure;

namespace PlanarSubdivisionExample
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Run();
}

static void Run()
{
float maxValue = 600;

#region create random points in the range of [0, maxValue]
PointF[] pts = new PointF[20];
Random r = new Random((int)(DateTime.Now.Ticks & 0x0000ffff));
for (int i = 0; i < pts.Length; i++)
pts[i] = new PointF((float)r.NextDouble() * maxValue, (float)r.NextDouble() * maxValue);
#endregion

Triangle2DF[] delaunayTriangles;
VoronoiFacet[] voronoiFacets;
using (PlanarSubdivision subdivision = new PlanarSubdivision(pts))
{
//Obtain the delaunay's triangulation from the set of points;
delaunayTriangles = subdivision.GetDelaunayTriangles();

//Obtain the voronoi facets from the set of points
voronoiFacets = subdivision.GetVoronoiFacets();
}

//create an image for display purpose
Image<Bgr, Byte> img = new Image<Bgr, byte>((int)maxValue, (int) maxValue);

//Draw the voronoi Facets
foreach (VoronoiFacet facet in voronoiFacets)
{
Point[] points = Array.ConvertAll<PointF, Point>(facet.Vertices, Point.Round);

//Draw the facet in color
img.FillConvexPoly(
points,
new Bgr(r.NextDouble() * 120, r.NextDouble() * 120, r.NextDouble() * 120)
);

//highlight the edge of the facet in black
img.DrawPolyline(points, true, new Bgr(Color.Black), 2);

//draw the points associated with each facet in red
img.Draw(new CircleF(facet.Point, 5.0f), new Bgr(Color.Red), 0);
}

//Draw the Delaunay triangulation
foreach (Triangle2DF triangles in delaunayTriangles)
{
img.Draw(triangles, new Bgr(Color.White), 1);
}

//display the image
ImageViewer.Show(img, "Plannar Subdivision");
}
}
}
```