Compiled OpenGL programs produce blank screens

norfenstein · 11-22-2004, 05:50 PM

I have OpenGL set up and working properly in Linux but whenever I compile a program that uses OpenGL for video I get only blank, black screens. The programs compile flawlessly and even run exactly as they should (sound, keyboard input, windowing, etc.) except I can't see anything. For example, the binary included in this simple tutorial works exactly as advertised, producing a captioned window with a white triangle in the center, pressing escape quits. If I compile it myself, however, using the included make file, I get a black empty window with a nice caption and pressing escape quits. I'm stumped, any help would be greatly appreciated.

linux 2.6.8.1
gcc 3.3.4
XFree86 4.3.0.1
nvidia driver 1.0-6111

dvm · 11-22-2004, 06:45 PM

Are you sure you're not changing anything? Every time (as long as I can remember) I had a blank screen was my fault.
Check your "reshape" or "resize' function callback and make sure you use a proper gluLookAt in the beginning of the "Display" function. Since the pre-built program is running ok, chances are you're messing something up.
Try starting with a simple thing as:

Code:

#include <GL/glut.h>

void display()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    glRectf(-0.5, -0.5, 0.5, 0.5);
    glutSwapBuffers();
}

int main(int argc, char *argv[])
{
    glutInitDisplayMode(GLUT_DOUBLE);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(100, 100);
    glutInit(&argc, argv);
    glutCreateWindow("Test");
    glutDisplayFunc(display);
    glutMainLoop();
}

Then compile with g++ <filename.cpp> -lglut
This should produce a small square in the middle of a small window.
If this doesn't work then I don't know what's wrong.

norfenstein · 11-22-2004, 10:46 PM

I can't think of anything wrong code-wise with the programs I tested: one was a full game with source I didn't touch, two were simple test programs that worked for me on Windows (no Windows specific code), and just to be sure I tried that tutorial to rule out run-time issues. I tried your code (after installing glut) and it worked, so it looks like the problem is with SDL which was the common thread between all the ones that didn't work. I don't know what the actual issue could be though, since everything else SDL related works, including 2D graphics.

norfenstein · 12-04-2004, 02:37 PM

Got the answer on a less trafficked forum. If anyone else is having the same problem, install the GL headers specific to your graphics card.