## Friday, 26 June 2015

### A Simple C++ Class for 3D Mesh Decimation

Some time ago I wrote a simple C++ class to simplify a 3D mesh. It is based on Michael Garland's article "Surface Simplification Using Quadric Error Metrics"

The code is available under a BSD license.

A win64 executable is also available for quick testing.

The code produces good quality results. However, it is relatively slow!

Usage:
MeshSimplification fileNameIn.obj targetNTrianglesDecimatedMesh targetNVerticesDecimatedMesh maxDecimationError fileNameOut.obj

For instance, to generate a decimated mesh with 1000 triangles use the following command line:
MeshSimplification input.obj 1000 0 1.0 decimated.obj

To generate a decimated mesh with 1000 vertices:
MeshSimplification input.obj 0 1000 1.0 decimated.obj

To generate a decimated mesh with an error of 1%:
MeshSimplification input.obj 0 0 0.01 decimated.obj

To use the mesh decimation class in your code, proceed as follows:

```// input mesh
Vec3<Float> * points;
Vec3<int> * triangles;

// Fill points and triangles with input mesh
// ...

// decimate mesh
MeshDecimator myMDecimator;
myMDecimator.Initialize(nPoints, nTriangles, points, triangles);
myMDecimator.Decimate(targetNVerticesDecimatedMesh, targetNTrianglesDecimatedMesh, maxDecimationError);

// allocate memory for decimated mesh
size_t nVerticesDecimatedMesh = myMDecimator.GetNVertices();
size_t nTrianglesDecimatedMesh = myMDecimator.GetNVertices();
Vec3<Float> * decimatedMeshPoints = new Vec3<Float>[nVerticesDecimatedMesh];
Vec3<int> * decimatedMeshTriangles = new Vec3<int>[nTrianglesDecimatedMesh];

// retrieve decimated mesh
myMDecimator.GetMeshData(decimatedMeshPoints, decimatedMeshTriangles);```

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