OpenGL - XY Coordinate Rendering

[FalterrisAunvre]

I've recently been trying to learn OpenGL (the 2d elements of it) for use in games. I know about the glOrtho() function, and how you can reset the rendering coordinates (the 1.0 through -1.0 annoys me to no end). However, I can't figure out how to set it to have no negative coordinates, for those of you who are familiar with SDL-style coordinates, this is what I'm going for:
http://bit.ly/12nsoty

But with OpenGL, it seems that glOrtho() takes it's X an Y parameters, halves them, and assigns them a positive and a negative (ex. 640X480, supposed to be 0-640 and 0-480, but instead uses -320-320 and -240-240).

My test program and its results (lines and text added later)
http://imgur.com/6wWBkgl

My code:

        ...
	glMatrixMode( GL_PROJECTION );
	glLoadIdentity();
	glOrtho( 0.0, SCREEN_WIDTH, SCREEN_HEIGHT, 0.0, 1.0, -1.0 );

	glMatrixMode( GL_MODELVIEW );
	glLoadIdentity();

	glClearColor( 0.f, 0.f, 0.f, 1.f );

        ...

        glClear( GL_COLOR_BUFFER_BIT );

	glMatrixMode( GL_MODELVIEW );
	glLoadIdentity();

	glTranslatef( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f, 0.f );

	glBegin( GL_QUADS );
		glColor3f( 0.f, 1.f, 1.f );
		glVertex2f( 100.f, 100.f );
		glVertex2f( 0.f, 100.f );
		glVertex2f( 0.f, 0.f );
		glVertex2f( 100.f, 0.f );
	glEnd();
        ...

Does anyone have any good suggestions as to how I could either fix and/or work around this problem? any and all help would be appreciated. Thanks,
Aunvre

[htirwin]

Can you just change the arguments to glTranslatef appropriately? If not you can just abstract the rendering call and convert the coordinates before rendering.

On a side note you might want to start learning a more modern version of openGL. The functions you're using have been depreciated for years; although with 2d, performance probably isn't an issue.

[Disch]

FWIW, you are learning outdated and deprecated OpenGL. I highly recommend abandoning whatever source you're using and use a more recent tutorial/source.

This was is pretty good:

http://www.arcsynthesis.org/gltut/