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Window Size and Projection

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Hi, I am not sure that I understand windowsize,projection and world size properly. I am trying to create a program with a world of size (wX,wY). The total window size should be larger though and is in the variables (winX,winY). My program is only in 2D. How do I set the world background color and how do I set the "world" background color? I am doing the following atm and it is not working right. glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(winX,winY); glutInitWindowPosition(windowPosx,windowPosy); glutCreateWindow("Program"); glutDisplayFunc(display); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0,wX,0.0,wY); glMatrixMode(GL_MODELVIEW); glClear(GL_COLOR_BUFFER_BIT);

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what is the purpose of gluOrtho2D(0.0,wX,0.0,wY) ?

That call creates a matrix for projecting 2D coordinates onto the screen.

Vertex coordinates with x-values between 0 and wX will appear on the screen at positions from screen-left to screen-right. Similarly for y-values and 0 to wY projected to the screen height.

I would strongly recommend you get yourself a copy of OpenGL Programming Guide, otherwise know as "The Red Book." It is the Bible of OpenGL programming and describes all the OpenGL functions.

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How do you setup a different color for the window background and another color for the "world"?

To set the window background:

glClearColor(floatRed, floatGreen, floatBlue, floatAlpha);
glClear(GL_COLOR_BUFFER_BIT);

where the red/green/blue/alpha parameters describe the color you want (which you may already know).

I'm not sure what you mean by "world" color. If you mean setting the color of an object you want to render, set glColor (rather than glClearColor) before you draw the object.

If you mean the background displayed for the "world," that's the window background color.

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