I have a simple program that starts up and draws a 640x480 window and displays a few points.
I set up my window with :
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(SCREEN_HEIGHT /640/, SCREEN_WIDTH /480/);
glutInitWindowPosition(100,150);
glutCreateWindow(“My window”);
To initially draw the first picture I call this:
glutDisplayFunc(DrawIt);
Here is DrawIt:
void DrawIt() {
gluOrtho2D(0.0 , SCREEN_WIDTH , 0.0 , SCREEN_HEIGHT);
glClear(GL_COLOR_BUFFER_BIT); //clear the screen
glBegin (GL_POINTS);
glVertex2i(100, 50);
glVertex2i(100, 130);
glVertex2i(150 , 130);
glEnd();
glFlush(); //send all output to display
}
Now the problem, I want the user to be able to hit any key, and I want to draw a different picture. Only the world coordinates could be from 0.1 to 0.9, instead of from 0->640 and 0->480. How do I set up the new mapping. Another call to gluOrtho2d(0.0 , 1 , 0.0 ,1); doesnt seem to work.