Can't create shader program from a python thread about moderngl HOT 3 CLOSED

Hi, thanks for the help, I've ended up using a dedicated render process which works quite nicely. I'll close this issue as resolved.

from moderngl.

Upon further testing a similar issue seems to occur when calling ctx.simple_vertex_array(self.prog, self.vert_buff, 'in_vert', 'in_color') in a thread (resulting in the following error: _moderngl.Error: cannot create vertex array). This is after having successfully called ctx.program from the main thread.

from moderngl.

if you are using threads you must handle opengl context switching,
the opengl context can be current only in one thread.
there are some methods (begin, end) in glcontext, but not sure if you need those.
with raw api call it looks like the following:

wglMakeCurrent(...)
# can call moderngl code here
wglMakeCurrent(NULL, NULL)

check the docs what happens when another thread calls wglMakeCurrent while the context is active in some other thread. you may have to add some mutexes.

also please do keep in mind that due to the Python GIL you have no real benefits of using threads unless those are idling on IO without the GIL being held.

the OpenGL driver is not multithreaded so whatever you do with it on multiple threads it will land in sync calls one after the other.

PS:

If you want to put rendering on a dedicated thread, that may be totally reasonable and you should make the opengl context current there and leave it like that.

from moderngl.