# Circle example

To test out our new algorithm for triangle-triangle intersections, we take an example suggested by Frederic Hecht. We begin by constructing a mesh representing a circle. There is a point at the centre and a number of points around the perimeter, equally spaced. Next, we make a copy of this mesh, adjust its position slightly and rotate is by a small fraction of pi.

[N,T,Np]=CircleMesh(20,0.5*eps); PlotMesh(N,T,'b') PlotMesh(Np,T,'r')

The two meshes appear identical, but there is a separation between them. This separation is so small it can cause errors when trying to intersect the meshes. We use the original PANG to intersect them.

M = PANG(N,T,Np,T);

We see that PANG is unable to calculate the intersection of all of the triangles. We try again with our new algorithm.

clf PlotMesh(N,T,'b') PlotMesh(Np,T,'r') M = MeshIntersect(N,T,Np,T);