Mesh.fromGrid(BitmapData bitmapData, int columns, int rows)

Create a new grid shaped Mesh with the desired number of columns and rows. A 2x2 grid will create 9 vertices.

Source 

factory Mesh.fromGrid(BitmapData bitmapData, int columns, int rows) {

  var width = bitmapData.width;
  var height = bitmapData.height;
  var vertexCount = (columns + 1) * (rows + 1);
  var triangleCount = 2 * columns * rows;
  var mesh = new Mesh(bitmapData, vertexCount, triangleCount);

  for (int r = 0, vertex = 0; r <= rows; r++) {
    for(int c = 0; c <= columns; c++) {
      var u = c / columns;
      var v = r / rows;
      var x = width * u;
      var y = height * v;
      mesh.setVertex(vertex++, x, y, u, v);
    }
  }

  for (int r = 0, triangle = 0; r < rows; r++) {
    for (int c = 0; c < columns; c++) {
      var v0 = (r + 0) * (columns + 1) + c + 0;
      var v1 = (r + 0) * (columns + 1) + c + 1;
      var v2 = (r + 1) * (columns + 1) + c + 1;
      var v3 = (r + 1) * (columns + 1) + c + 0;
      mesh.setTriangleIndices(triangle++, v0, v1, v3);
      mesh.setTriangleIndices(triangle++, v1, v3, v2);
    }
  }

  return mesh;
}