On 13/03/17 11:09, Emil Velikov wrote:
On 11 March 2017 at 11:51, Federico Dossena <dossenu...@gmail.com> wrote:
In the last week I've been trying to bring an "old" game back to life, Star
Wars Knights of the old republic (KOTOR, for short). It's from 2003 and uses
OpenGL 1.4.
I have used Mesa, libtxc_dxtn and some trickery to decompress the textures
to boost performance, and right now I have it up and running smoothly with
Gallium on LLVMPipe, compiled on Windows. (I can upload a copy if someone is
interested). This took me about 2 days of compiling and figuring out stuff.
Here's where the weirdness begins:
Turning on framebuffer effects or soft shadows make the game crash right
after the menu. Using a disassembler and debugger and what little knowledge
I have of reverse engineering, I managed to track down the issue to a
function which uses wglGetProcAddress to get the addresses of several OpenGL
functions. Some of these calls return a null pointer (even if there is a
valid context and it is current), and when the game tries to call them, it
crashes. The first one that makes it crash is a pointer to
wglBindTexImageARB, but there are a few others. NOPing the offending
instructions did not work, and returning a nop function just makes the game
display artifacts.
Strange - afaict mesa (st/wgl) exposes both wglBindTexImageARB and the
WGL_ARB_render_texture extension.
You can break on DrvGetProcAddress and trace where/how we end up with
NULL function pointer.
-Emil
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
Federico,
You should be using latest master for this. There have been recent
changes/fixes to our WGL implementation.
Last fall Brian Paul fixed an issue with WGL extension seen on KOTOR.
I'm not sure the the issue has been crossported to Mesa master yet, and
it might be unrelated.
Generally speaking, wglGetProcAddress returning NULL by itself is not a
problem. Many games wrongly rely on wglGetProcAddress NULL results to
detect whether an GL/WGL extension is present (which goes against the
spec). Other libraries try to bindly get every possible entrypoint
through wglGetProcAddress, then check which ones to use based on
supported extensions (which is actually fine by the spec.)
For the record, getting an apitrace is usually useful to debug this sort
of issues. One can use apitrace straigh from windows or with WINE --
https://github.com/apitrace/apitrace/wiki/WINE
Jose
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
