How to flip a texture via the texture matrix?

Topic is the question I got.
I have got 6 cubemap textures (1 for each direction), that are not flipped (It seems that cubemap textures don´t have to be flipped in order to be drawn correct in OpenGL, right?).
Now I want to use these 6 textures for a skybox and then they have to be flipped, right?
The question is how can I do this via the texture matrix, so that I don´t need 12 textures (6 cubemap textures and these 6 flipped, so that they are suitable for the skybox)!


I flipped my 6 cubemap textures and found out a strange thing.
The textures for:

  • neg x
  • neg z
  • pos x
  • pos y
  • pos z
    Have to be flipped on the x axis in order to be correct as skybox textures, BUT
  • neg y (the floor)
    has to be mirrored on the y axis in order to be correct as skybox texture … WHY THIS?


dunno… /me sukz @ cuby mapping

Oh, I’m sorry, did I write it like that? :stuck_out_tongue: