Front face change - any help appreciated!

OpenGL Development
#1

Hi again!

I’m having a really weird problem with my call to glOrtho(), in that when I call it as GL11.glOrtho(0, Display.getDisplayMode().getWidth(), 0, Display.getDisplayMode().getHeight(), -1, 1); and then draw my quad, the quad displays as I would expect. I draw my quad while my Front Face is Counter-Clockwise (call glFrontFace(GL_CCW); when I init the OpenGL stuff).

However, my problem arises when I try calling glOrtho() as GL11.glOrtho(0, Display.getDisplayMode().getWidth(), Display.getDisplayMode().getHeight(), 0, -1, 1);. Here, my quad doesn’t display anywhere! After some fiddling around, I found that if I changed the ordering of my vertices on my quad to make them Clockwise, it drew fine!

So my question is, does anyone know why this is so? It seems like the Front Face changes unexpectedly when I change my coordinate system using the glOrtho call. I’m guessing there is some concept I’m missing when you change coordinate systems, but I’m really at a loss.

Thanks for any help! I appreciate it!

Cheers

Jarrett

#2

Don’t you think that it makes a lot of sense that once you flip the vertical axis, counter-clockwise becomes clockwise?

Just imagine it, when you make a video of a clock, flip the vertical axis, it will rotate in the opposite direction

#3

Ahhhh okay, I just wrote it out on paper and then reversed it, makes total sense haha. I thought maybe I had broken my OpenGL :\

Thanks for the insight Riven!