Hooking - suggested options besides EndScene?

[flo8464]

Also because WoW uses the TLS to store data for use in WoW's mainthread and you can't simply call all functions from your own thread.

[Cypher]

Also because WoW uses the TLS to store data for use in WoW's mainthread and you can't simply call all functions from your own thread.

In other words, exactly what Main already covered, lol. Thread safety.

You can easily 'spoof' the TLS values and call engine functions, however that's dangerous because it's not thread-safe. There's a reason that data is in TLS.

[I Hypnotoad I]

I'm sorry if I sound off topic here.. I really am but..

Am I the only one who misread the title to be 'Hookering' ?

EDIT: Nothing I cant say that has already been said to support this issue. But really bro? People joke on this forum all the time. You don't see them getting in any trouble for it.
It would've been nice for you to tell me yourself instead of stating something in your own world. (IE: Inside reference "Yes, Go Away") Instead, I had to find out myself..

[Cypher]

I'm sorry if I sound off topic here.. I really am but..

Am I the only one who misread the title to be 'Hookering' ?

Yes. Go away.

[pred.is.god]

I'm sorry if I sound off topic here.. I really am but..

Am I the only one who misread the title to be 'Hookering' ?

I didnt misread it, but i lol'd at the title neverless

[Sednogmah]

Regarding which function to hook:

WoW calls glClear several times within the rendering of 1 frame, each time with different parameters. It hasn't proven itself as a reliable point to hook, at least not for me personally. glXSwapBuffers however is only called exactly once and WoW's engine is in a consistent state at that point. You might want to try that instead.

As a bonus, glXSwapBuffers retrieves the GLXDrawable as a parameter which allows you to take screenshots or even stream the whole game over the network with decent FPS.

How you could hook:

I'm not very familiar with Mac OS X either but it seems that it has a feature that's very similar to Linux/BSD LD_PRELOAD: DYLD_INSERT_LIBRARIES. -- if it does what I think it does, you should be able to replace library functions like glXSwapBuffers or glClear with your own code, do your dirty work inside & then call the real function.

[eLaps]

glClear however is only called exactly once and WoW's engine is in a consistent state at that point. You might want to try that instead.

Anyone got it to work on linux (wine)?

[audible83]

Yes, works perfectly with Wine

[eLaps]

Uh nervermind I was trying to hook it like glClear :d

[Sednogmah]

hook-glx.c:

#define _GNU_SOURCE
#include <dlfcn.h>

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <GL/gl.h>
#include <GL/glx.h>

void hookfunc();

/* glXSwapBuffers() is very appropriate as an "end scene" hook because
 * WoW calls it exactly once, at the end of each frame.
 *
 * Unfortunately WINE needs to be patched to allow hooking this via
 * LD_PRELOAD.
 *
 * 1) Instead of using the default RTLD loader, WINE retrieves the address
 *    for glXGetProcAddressARB directly from the OpenGL library.
 *    This is done to enable binary compatibility to systems with or without
 *    OpenGL.
 *
 *    Solution: patch WINE to use the default loader
 *
 * 2) WINE gets the pointers to glx functions via glXGetProcAddressARB
 *    
 *    => I'm hooking glXGetProcAddressARB and return my own
 *       pointer to glXSwapBuffers.
 *
 */

typedef __GLXextFuncPtr (*fp_glXGetProcAddressARB) (const GLubyte*);
typedef __GLXextFuncPtr (*fp_glXSwapBuffers)(Display* dpy, GLXDrawable drawable);

// glXSwapBuffers
fp_glXSwapBuffers real_glXSwapBuffers;

void my_glXSwapBuffers(Display* dpy, GLXDrawable drawable) {
        real_glXSwapBuffers(dpy, drawable);
        hookfunc();
}

// glXGetProcAddressARB
__GLXextFuncPtr glXGetProcAddressARB (const GLubyte* procName)
{
        __GLXextFuncPtr result;
        printf("* hook-glx.c: glXGetProcAddressARB(\"%s\")\n", procName);

        // Fetch pointer of actual glXGetProcAddressARB() function
        static fp_glXGetProcAddressARB lib_getprocaddr = NULL;
        if(!lib_getprocaddr)
        {
                char* errorstr;
                lib_getprocaddr = (fp_glXGetProcAddressARB) 
                        dlsym(RTLD_NEXT, "glXGetProcAddressARB");
                if( (errorstr = dlerror()) != NULL )
                {
                        fprintf(stderr, "dlsym fail: %s\n", errorstr);
                        exit(1);
                }
        }
        result = lib_getprocaddr(procName);

        // Return our own function pointers
        if( strcmp( (const char*) procName, "glXSwapBuffers" ) == 0 )
        {
                real_glXSwapBuffers = (fp_glXSwapBuffers) result;
                return (__GLXextFuncPtr) my_glXSwapBuffers;
        }
        // Return default function pointer
        return lib_getprocaddr(procName);
}

WINE patch:

diff -Nru wine-1.1.39.orig/dlls/winex11.drv/opengl.c wine-1.1.39/dlls/winex11.drv/opengl.c
--- wine-1.1.39.orig/dlls/winex11.drv/opengl.c  2010-02-27 02:21:02.973526893 +0100
+++ wine-1.1.39/dlls/winex11.drv/opengl.c       2010-02-27 02:27:11.231401387 +0100
@@ -412,7 +412,7 @@
         return FALSE;
     }
 
-    pglXGetProcAddressARB = wine_dlsym(opengl_handle, "glXGetProcAddressARB", NULL, 0);
+    pglXGetProcAddressARB = wine_dlsym(RTLD_DEFAULT, "glXGetProcAddressARB", NULL, 0);
     if (pglXGetProcAddressARB == NULL) {
         ERR("Could not find glXGetProcAddressARB in libGL, disabling OpenGL.\n");
         goto failed;

[eLaps]

WINE patch:

diff -Nru wine-1.1.39.orig/dlls/winex11.drv/opengl.c  wine-1.1.39/dlls/winex11.drv/opengl.c
--- wine-1.1.39.orig/dlls/winex11.drv/opengl.c   2010-02-27 02:21:02.973526893 +0100
+++ wine-1.1.39/dlls/winex11.drv/opengl.c        2010-02-27 02:27:11.231401387 +0100
@@ -412,7 +412,7 @@
          return FALSE;
     }
 
-    pglXGetProcAddressARB =  wine_dlsym(opengl_handle, "glXGetProcAddressARB", NULL, 0);
+     pglXGetProcAddressARB = wine_dlsym(RTLD_DEFAULT, "glXGetProcAddressARB",  NULL, 0);
     if (pglXGetProcAddressARB == NULL) {
          ERR("Could not find glXGetProcAddressARB in libGL, disabling  OpenGL.\n");
         goto failed;

Credit goes to RoKFenris from this thread I suppose.