Problem with allegro_gl

Problem with allegro_gl_flip();

Sophat Pheng

Member #5,774

April 2005

I just compile Allegro 4.2.1 and AllegroGL 0.4.1 with mingw32 3.4.2. I'm using MSVC8 so I built them with the "fix msvc8" command. I built a debug version as well. Instead of generating agl.lib and agld.lib, it generated agl_s.lib and agld_s.lib. (static?) Anyway, I linked to those libraries and I tried running this example provided with AllegroGL.

1#include <allegro.h>
2#include <alleggl.h>
3 
4int main() {
5 
6  /* Initialize both Allegro and AllegroGL */
7  allegro_init();
8  install_allegro_gl();
9 
10  /* Tell Allegro we want to use the keyboard */
11  install_keyboard();
12 
13  /* Suggest a good screen mode for OpenGL */
14  allegro_gl_set(AGL_Z_DEPTH, 8);
15  allegro_gl_set(AGL_COLOR_DEPTH, 16);
16  allegro_gl_set(AGL_SUGGEST, AGL_Z_DEPTH | AGL_COLOR_DEPTH);
17 
18  /* Set the graphics mode */
19  set_gfx_mode(GFX_OPENGL_WINDOWED, 640, 480, 0, 0);
20 
21  /* Clear the screen */
22  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
23 
24  /* Set up the view frustum */
25  glMatrixMode(GL_MODELVIEW);
26  glLoadIdentity();
27  glFrustum(-1.0, 1.0, -1.0, 1.0, 1, 60.0);
28 
29  /* Draw a quad using OpenGL */
30  glBegin(GL_QUADS);
31  glColor3ub(255, 255, 255);
32  glVertex3f(-1, -1, -2);
33  glVertex3f( 1, -1, -2);
34  glVertex3f( 1,  1, -2);
35  glVertex3f(-1,  1, -2);
36  glEnd();
37 
38  /* Flip the backbuffer on screen */
39  allegro_gl_flip();
40 
41  /* Wait for the user to press a key */
42  readkey();
43 
44  /* Finished. */
45  return 0;
46}
47END_OF_MAIN()

The application crashed when calling allegro_gl_flip(); I stepped into it and it goes there

void allegro_gl_flip(void)
{
  __allegro_gl_driver->flip();
}

where __allegro_gl_driver is NULL.

Any ideas?

Thanks!

Kitty Cat

Member #2,815

October 2002

Check all return values of functions that can fail. One of them is failing, but you're assuming they don't.

--
"Do not meddle in the affairs of cats, for they are subtle and will pee on your computer." -- Bruce Graham

Sophat Pheng

Member #5,774

April 2005

As you said, this call fails.
install_allegro_gl();

It actually fails right from the start.

int install_allegro_gl(void)
{
  if (!system_driver)
    return -1;
// ...

Why is that?

Richard Phipps

Member #1,632

November 2001

Do you have the latest OpenGL drivers installed on your machine?

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Sophat Pheng

Member #5,774

April 2005

I think I have OpenGL driver Version 6.14.10.6347 that comes with my graphic card drivers. I don't think it is the latest but it should not be that old either. Should I get the latest?

Richard Phipps

Member #1,632

November 2001

Can you give us some details on your graphic card? Some gfx cards have no or poor OpenGL drivers. It is normally always a good idea to update to the latest drivers to improve poor ones..

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Free Logging System Code & Blog

Milan Mimica

Member #3,877

September 2003

Sophat: I'd say that allegro_init(); also failed.

--
M.M.
http://sparklet.sf.net

Sophat Pheng

Member #5,774

April 2005

I have a All-In-Wonder Radeon 9800 128MB.

Milan : Why would you say that ?

By the way, I can run the examples built with AllegroGL.

Milan Mimica

Member #3,877

September 2003

Because "system_driver" is a allegro variable initialized at allegro_init().
Strange that examples work.
Have you had any older version of allegrogl installed before? Maybe something is left and there are conflicts... just guessing.

--
M.M.
http://sparklet.sf.net

Sophat Pheng

Member #5,774

April 2005

It is the first time I've built AllegroGL myself.

Also when I stepped into allegro_init();

"system_driver" was definitely and allegro_init() returns 0.

From my watch window :
system_driver 0x100d0de0 _system_directx {id=1146626080 name=0x100eb698 "" desc=0x100eb698 "" ...} SYSTEM_DRIVER *

I am getting very confuse.

Thanks for any inputs.

Milan Mimica

Member #3,877

September 2003

Hm, I used to see that when symbols from DLL where not imported correctly... But I can't see anything wrong here.
You can try building AllegroGL using MSVC8 project files. It's in projects/ directory.

edit: You are using Allegro as a DLL, right?

--
M.M.
http://sparklet.sf.net

Sophat Pheng

Member #5,774

April 2005

Solved. You were right. I remove alld.lib from the dependencies.

Thanks a lot for your help and patience