Ear Clipping Triangulation Job

Implementation of the Triangulation by Ear Clipping inside Unity's Job System. The basic algorithm is explained in this paper.

How to use it

Define and init the SinglePolygonData structure using the constructor available.

SinglePolygonData (Allocator allocator, Vector2[] contourn, Vector2[][] holes = null)

The contourn points array must be in counter clockwise order.

The points of every hole inside the holes array must be in clockwise order.

Define the NativeArray that will contain the triangles indexes as output of the job.

int totNumVerts = polygon.HolesNum * 2 + polygon.VerticesNum;
int ntris = (totNumVerts - 2) * 3;
NativeArray<int> outTriangles = new NativeArray<int>(ntris, Allocator.TempJob);

Create and schedule the ECTriangulatorJob.

ECTriangulatorJob triangulatorJob = new ECTriangulatorJob()
{
    Polygon = polygon,
    OutTriangles = outTriangles
};
JobHandle handle = triangulatorJob.Schedule();

When the job is completed you can get the triangles.

int[] triangles = new int[outTriangles.Length];
for (int i = 0; i < outTriangles.Length; ++i)
{
    triangles[i] = outTriangles[i];
}  

Dispose the polygon data structure and the triangles native collection used previously.

polygon.Dispose();
outTriangles.Dispose();

Consider to take a look to the TestEarClippingJob script to see the algorithm in action.

Notes

The algorithm is implemented using the NativeLinkedList<T> created by Jackson Dunstan in his repository about Native Collections. To use this code you will need to enable the "unsafe" code execution inside the project settings panel.