[Scummvm-tracker] [ScummVM :: Bugs] #13215: OpenGLSdlGraphics3dManager::setupScreen() might invoke `glGetIntegerv` without GL context

[ScummVM :: Bugs]

#13215: OpenGLSdlGraphics3dManager::setupScreen() might invoke `glGetIntegerv`
without GL context
-------------------+----------------------------
Reporter:  GMTA    |       Owner:  (none)
    Type:  defect  |      Status:  new
Priority:  low     |   Component:  Common
 Version:          |  Resolution:
Keywords:          |        Game:  Grim Fandango
-------------------+----------------------------
Description changed by GMTA:

Old description:

> When switching from the launcher to an OpenGL game such as Grim Fandango,
> the GL context is destroyed and then created again. To create a new
> context, `OpenGLSdlGraphics3dManager::setupScreen()` is invoked. Before
> it actually created a new context, the MSAA sample count is retrieved
> with:
>
> {{{
> SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &currentSamples);
> }}}
>
> This in turn invokes `glGetIntegerv`. According to the OpenGL spec,
> invoking any API without an active GL context results in undefined
> behavior.
>
> While porting ScummVM to SerenityOS, I have had to patch out the above
> call to make Grim Fandango work at all. This is not a fix but a
> workaround, but it might be useful for you to see.
>
> A possible solution would be to make sure to only retrieve the samples
> when a GL context exists.

New description:

 When switching from the launcher to an OpenGL game such as Grim Fandango,
 the GL context is destroyed and then created again. To create a new
 context, `OpenGLSdlGraphics3dManager::setupScreen()` is invoked. Before it
 actually created a new context, the MSAA sample count is retrieved with:

 {{{
 SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &currentSamples);
 }}}

 This in turn invokes `glGetIntegerv`. According to the OpenGL spec,
 invoking any API without an active GL context results in undefined
 behavior.

 While porting ScummVM to SerenityOS, I have had to patch out the above
 call to make Grim Fandango work at all. This is not a fix but a
 workaround, but it might be useful for you to see.

 A possible solution would be to make sure to only retrieve the samples
 when a GL context exists.

 Related SerenityOS PR: https://github.com/SerenityOS/serenity/pull/11831

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Ticket URL: <https://bugs.scummvm.org/ticket/13215#comment:1>
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