CODEWITHSUNDEEP
c++openglglutglew
w00
w00

Reputation: 26772

How to initialize glut with fake parameters?

I'm using opengl, using the GLUT and GLEW libraries to create a plugin for a certain application.

This plugin doesn't start with a simple int main(argc, argv). So i can't pass these values to glutInit().

I tried something like this:

glutInit(0, NULL); <--- Crash
GLenum err = glewInit();

But i crashed when it tried to call the glutInit() function. Can i reconstruct those params some how, so that it won't crash and still be able to use the Glut library..??

Upvotes: 4

Views: 5463

Answers (4)

Dmytro
Dmytro

Reputation: 5213

I propose this as a de-facto standard for initializing glut applications.

static inline void glutInstall()
{
    char *glut_argv[] = { 
        "", 
        (char *)0  
    };
    int glut_argc = 0; 

    glutInit(&my_argc, my_argv);
}

This function can be modified on per-application basis to provide glut with the arguments it needs(if any), while permanently solving the issue of everyone asking why you are passing command line arguments to a 3rd party library.

Upvotes: 0

Doddy
Doddy

Reputation: 1259

Note the following code from the source (freeglut_init.c:677):

void FGAPIENTRY glutInit( int* pargc, char** argv )
{
    char* displayName = NULL;
    char* geometry = NULL;
    int i, j, argc = *pargc;
    ...

(Note the dereferencing.)

It seems that glutInit() does require a minimum of the process name, although the man page doesn't shed any light on this.

Upvotes: 3

Some programmer dude
Some programmer dude

Reputation: 409186

You might have to call glutInit with a valid argv parameter, even if you don't have any:

char *my_argv[] = { "myprogram", NULL };
int   my_argc = 1;
glutInit(&my_argc, my_argv);

Edit

It might also be that the first parameter is a pointer to an int, and it can't be NULL? Then it might be enough to only pass a valid argc parameter:

int my_argc = 0;
glutInit(&my_argc, NULL);

Upvotes: 4

BЈовић
BЈовић

Reputation: 64223

You can do it like this :

#include <GL/freeglut.h>

int main()
{
  char fakeParam[] = "fake";
  char *fakeargv[] = { fakeParam, NULL };
  int fakeargc = 1;

  glutInit( &fakeargc, fakeargv );

  //...
}

but take a note that it is an ugly hack.

Upvotes: 7

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