setDoubleBuffering(false) causes no output (black screen)

[liasomething]

to reproduce:

1. open ofBoxExample
2. in main.cpp replace
   ofSetupOpenGL(1024,768, OF_WINDOW);
   with

ofAppGLFWWindow window;
window.setDoubleBuffering(false);
ofSetupOpenGL(&window, 1024,768, OF_WINDOW);

3. compile and run

expected result: boxes on screen
actual result: black screen

of0.11, osX catalina 10.15.6

I downloaded master, but could not figure out how to make a project, as the project generator is missing.

[ofTheo]

Hi @liasomething !

From what I remember single buffering doesn't work on all platforms or graphics cards.
Are you trying to accumulate the screen buffer or is there a reason you want to disable double buffering?

If you want to accumulate the screen buffer you can do this in ofApp::setup()

    ofBackground(0, 0, 0);
    ofSetBackgroundAuto(false);

If that solves your issue feel free to close it.
If not it would be helpful to know more about what you are trying to achieve.

Cheers!
Theo

[liasomething]

Hi Theo,

I need to turn off double buffering, because at some point in my app I stop rendering (to deliberately pause the app) and with double buffering turned on and ofSetBackgroundAuto(false) the screen flickers between the last two frames rendered. Rendering into an fbo would solve my problem, but I assumed that if OF had a function called setDoubleBuffering() and I called it with false and did not get any error message, it would disable double buffering, silly me ! ;)

all the best
Lia.-

[ofZach]

it sounds like it should :). just a quick note that I see this line ifdef'd out for OS X

https://github.com/openframeworks/openFrameworks/blob/master/libs/openFrameworks/app/ofAppGLFWWindow.cpp#L178-L180

I'm not 100% why but maybe worth investigating if that's why it doesn't work properly on osx.

[liasomething]

Hi Zack,
thanks !
so, commenting out the ifndef did not help, but adding a hint for GLFW_DOUBLEBUFFER did:

// #ifndef TARGET_OSX
    //glfwWindowHint(GLFW_AUX_BUFFERS, settings.doubleBuffering ? 1 : 0 );
    glfwWindowHint(GLFW_DOUBLEBUFFER, settings.doubleBuffering ? GL_TRUE : GL_FALSE );
// #endif

i haven't tested this anywhere else, but it works for me.

all the best
Lia.-