I have a scene that I'm rendering first with a perspective matrix. I then want to rerender it in a different viewport using an orthographic matrix for a top-down 2D view of the scene. I think I may be missing something because I get nothing rendered with the orthographic projection.
To setup the ortho projection I create the matrix with the near/far set to (-1,1) (not sure how it affects rendering) and then move the camera up and pitch it 90 degrees and rerender the vertices without modification.
I'm using OpenGL4 with glm to produce the matrices.