code: func (b *Batch) MakeTriangles(t Triangles) TargetTriangles {
  	bt := &batchTriangles{
  		tri: t.Copy(),
  		tmp: MakeTrianglesData(t.Len()),
  		dst: b,
  	}
  	return bt
  }
docs: // MakeTriangles returns a specialized copy of the provided Triangles that draws onto this Batch.