The Triangulate Modifier converts all faces in a mesh (whether it be quads or n-gons) to triangular faces. This modifier fulfills the exact same function as the Triangulate tool in Edit Mode.
- Quad Method
Split the quads in nice triangles, slower method.
Split the quads on the 1st and 3rd vertices.
- Fixed Alternate
Split the quads on the 2nd and 4th vertices.
- Shortest Diagonal
Split the quads based on the distance between the vertices.
- N-gon Method
Arrange the new triangles nicely, slower method.
Split the n-gons using a scanfill algorithm.