How to get flat normals on a cube

Question

I am using OpenGL without the deprecated features and my light calculation is done on fragment shader. So, I am doing smooth shading.

My problem, is that when I am d

Answer 1

Another option would be to pass MV-matrix and the unrotated AxisAligned coordinate to the fragment shader:

 attribute aCoord;
 varying vCoord;
 void main() {
    vCoord = aCoord;
    glPosition = aCoord * MVP;
 }

At Fragment shader one can then identify the normal by calculating the dominating axis of vCoord, setting that to 1.0 (or -1.0) and the other coordinates to zero -- that is the normal, which has to be rotated by the MV -matrix.