On Mon, Oct 29, 2018 at 5:49 PM tim Rowledge <tim at rowledge.org> wrote:

>
>
> > On 2018-10-29, at 12:26 PM, Bert Freudenberg <bert at freudenbergs.de>
> wrote:
> >
> > On Sat, Oct 27, 2018 at 4:42 PM tim Rowledge <tim at rowledge.org> wrote:
> > Trying this out on a Raspberry Pi (obviously).
> > First major problem is that
> >
> > OGLUnix>>openGLLibraryName
> >         ^Smalltalk osVersion = 'linux'
> >                 ifTrue: ['libGL.so.1']
> >                 ifFalse: ['GL']
>
> It's actually a bit worse - the osVersion returned by Raspbian is
> 'linux-gnu' - so I tried changing that to
> openGLLibraryName
>         ^(Smalltalk osVersion beginsWith: 'linux')
>                 ifTrue: ['libGL.so.1']
>                 ifFalse: ['GL']
> which got a bit further.
>
> > has a #'' (apparently a ByteSymbol with just char value 0 in it) at the
> end of the method ; which of course a BlockClosure does not understand.
> >
> [snip]
> >
> > The" module: '#openGLLibraryName'>" looks a bit odd to me... shouldn't
> that have been recompiled to use the real library name?
> >
> > Yes, but it doesn't change the source code. Follow the senders of
> openGLLibraryName to see the magic.
>
> OK, so it's supposed to send #openGLLibraryName at some startup point.
> Very clever.


Yep, in OpenGL>>initialize it calls "self privateInstallLibrary: self
openGLLibraryName." which patches the library name into all compiled FFI
methods.

Unfortunately it appears something else goes wrong pretty quickly and
> OGLExtManager>>#loadExtension: uses glExtGetProcAddress: which even
> decompiled says
>         <cdecl: ulong 'glXGetProcAddressARB' (char*) module: 'GL'>
> Which doesn't seem right. Should it also use the #openGLLibraryName thing?
>

Ah, that seems to be an actual bug.

#privateInstallLibrary: does not go into the subclasses. In OGLWin32, that
method has the correct 'opengl32.dll'  module.  OGLMacOSX uses a different
mechanism entirely. And OGLUnix relies on "GL" linking to the right thing.

So I'd say in privateInstallLibrary: we need to patch both OpenGL and
OGLUnix.

- Bert -
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