I have discovered something remarkable. I know that Apple has deprecated OpenGL, but still. This situation is appalling:
When Apple’s GLUT framework calls the handleResize callback (AKA reshape), it provides a window width & height that are quite bogus. The bigger the window, the smaller the width. The taller the window, the shorter the height. And the inverse is true.
I am using glViewport and glOrtho.
In addition, calling glutGet (GLUT_WINDOW_WIDTH) and glutGet (GLUT_WINDOW_HEIGHT) also provides these bogus values.
Also provide these bogus width and height values.
The effect is, if I draw a triangle that goes from left side to right side, top to bottom, is almost never touches the top and the right edges.
But the same code runs fine on GNU/Linux.
Is there a way on MacOS for me to get the true window size without messing with their broken GLUT?