I’m new to OpenGL and there are a few things which I didn’t really get when I read through my OpenGL book: the Viewport, Clipping areas or volumes and parallel projections.
In the text it says that if you want to draw in a window you have to tell OpenGL which coordinate system you want to use and how it should be translated into screen coordinates.
Furthermore it says that this can be done by specifying the Clipping area.
In the next step the viewport maps the clipping area to physical screen coordinates.
I wrote a program which draws a rectlange but nowhere I need to specify the clipping area of a window.
I just have to set the window’s heigth and width, and can start drawing without concerning about the minimum and maximum x, and y range ( I don’t mention the z axis here, because I just want to draw 2d stuff first ).
So my assumption is that the coordinates which I use to draw exactly match with the window.
Even if I change the original size of the window, I can draw in every part of it.
So, where do I need any translation then?
Why and where do I have to specify the clipping area if it seems to me to match exactly with the current windows size (in pixels) ?
By the way:
What are orthographical projections?
What do they do?
When do I need them?
I’m really frustrated…
I would appreciate any help,