CODEWITHSUNDEEP
openglcallbackgluttiming
linello
linello

Reputation: 8714

How to control finely the glut inner loop

I would like to control the main loop in a glut program, I would like to better understand what is the order of execution of the following callbacks:

glutDisplayFunc(drawGLScene);
glutIdleFunc(idle);
glutTimerFunc(TIMER_MS, update, 0);

It's difficult for me to understand how glut queues this calls in a program.

Upvotes: 3

Views: 535

Answers (2)

Andrew Rasmussen
Andrew Rasmussen

Reputation: 15109

You can't. If you want to control the main loop you're going to have to use something like GLFW. Freeglut, a more modern extension of glut might let you do this. The way GLUT works is you specify some callbacks, start the main loop, and then it will call the callbacks whenever appropriate.

It probably calls the timer callback at the beginning of the frame so that you can update your time-since-last-frame value, it probably calls the display callback whenever it needs to render a frame, and it probably calls the idle callback whenever it has to wait before rendering the next frame (maybe in the case that your framerate is limited to exactly 60 fps so if you are rendering frames in less than .017 seconds then it will probably call the idle callback until it is ready to push a frame to the screen).

Upvotes: 1

datenwolf
datenwolf

Reputation: 162367

As soon as you want fine control of your event loop, it's time to abandon GLUT. Use SDL, GLFW or do it from scratch. Understanding the inner workings of GLUT will not help you to gain fine control.

Upvotes: 6

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