[SOLVED] display callback fails after dist upgrade

piobair · 12-02-2023, 12:11 PM

william@geeves:~/projects/gnutran$ uname -a
Linux geeves 6.1.0-13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.55-1 (2023-09-29) x86_64 GNU/Linux
libglut-dev 3.4.0-1

I tried to run a program that used to run perfectly, and received the error:
./gnutran: error while loading shared libraries: libglut.so.3: cannot open shared object file: No such file or directory

So I recompiled the program, ran it and got:
freeglut (./gnutran): ERROR: No display callback registered for window 2

Subject code:

Code:

    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
//    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(WindowWidth, WindowHeight);
    glutInitWindowPosition(100, 100);
  mainWindow = glutCreateWindow(argv[1]);
  glutReshapeFunc(reshape);
  
  glutInitWindowSize(TWindowWidth, TWindowHeight);
  glutInitWindowPosition(800, 200);
  textWindow = glutCreateWindow("textbox");
  glutReshapeFunc(reshapeText);
  
  glutSetWindow(mainWindow);
    GLenum err = glewInit();
    if (GLEW_OK != err){
      /* Problem: glewInit failed, something is seriously wrong. */
      fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
    }
  init();
  glutDisplayFunc(display);
  glutDisplayFunc(displayText);

Presumably it does not like something about

Code:

glutDisplayFunc(displayText)

Can someone give me a clue?

NevemTeve · 12-03-2023, 12:29 AM

Please provide a minimal complete verifiable example.
https://stackoverflow.com/help/minim...ucible-example

piobair · 12-04-2023, 03:03 PM

Verifiable example:
Note that lines 63 - 66, 69 (window 2) are commented out. The result is similar to a "Hello World", and displays window1.
If instead I comment out lines 58 - 61, 68 (window 1) and recompile, window2 is displayed.
If none of the code is commented out, the result is the error message:

Quote:

freeglut (./reshape_test): ERROR: No display callback registered for window 1

Code:

// reshape_test.c
// compile as gcc reshape_test.c -o reshape_test -lglut -lGLEW -lGL

#include <GL/glut.h>
int firstWindow, secondWindow;

void display1(){
	glutSetWindow(firstWindow);
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glClear(GL_COLOR_BUFFER_BIT);
	glLoadIdentity();
	glColor3f(0.0, 1.0, 0.0);
	
	glBegin(GL_POLYGON);
	glVertex3f(0.0, 0.0, 0.0);
	glVertex3f(0.5, 0.0, 0.0);
	glVertex3f(0.5, 0.5, 0.0);
	glVertex3f(0.0, 0.5, 0.0);
	glEnd();
	
	glFlush();
	glutSwapBuffers();
}

void display2(){
	glutSetWindow(secondWindow);
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glClear(GL_COLOR_BUFFER_BIT);
	glLoadIdentity();
	glColor3f(1.0, 0.0, 0.0);
	
	glBegin(GL_POLYGON);
	glVertex3f(0.0, 0.0, 0.0);
	glVertex3f(0.5, 0.0, 0.0);
	glVertex3f(0.5, 0.5, 0.0);
	glVertex3f(0.0, 0.5, 0.0);
	glEnd();
	
	glutSwapBuffers();
	glFlush();
}

void reshape1(int w, int h){
  glutSetWindow(firstWindow); 
  glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  display1();
}

void reshape2(int w, int h){
  glutSetWindow(secondWindow); 
  glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  display2();
}

int main(int argc, char* argv[]){
	glutInit(&argc,argv);
  glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize(300,100);
  glutInitWindowPosition(100, 100);
  firstWindow = glutCreateWindow("1st_window");
  glutReshapeFunc(reshape1);
  
/*	glutInitWindowSize(300,100);
  glutInitWindowPosition(600, 100);
  secondWindow = glutCreateWindow("2nd_window");
  glutReshapeFunc(reshape2);*/
  
  glutDisplayFunc(display1);
//  glutDisplayFunc(display2);
  
  glutMainLoop();
  return 0;
}

EdGr · 12-04-2023, 07:54 PM

The order matters.

You need to create the first window and set its reshape and display callbacks, and then create the second window and set its reshape and display callbacks.
Ed

Code:

// reshape_test.c
// compile as gcc reshape_test.c -o reshape_test -lglut -lGLEW -lGL

#include <GL/glut.h>
int firstWindow, secondWindow;

void display1(){
  glutSetWindow(firstWindow);
  glClearColor(0.0, 0.0, 0.0, 0.0);
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  glColor3f(0.0, 1.0, 0.0);

  glBegin(GL_POLYGON);
  glVertex3f(0.0, 0.0, 0.0);
  glVertex3f(0.5, 0.0, 0.0);
  glVertex3f(0.5, 0.5, 0.0);
  glVertex3f(0.0, 0.5, 0.0);
  glEnd();

  glFlush();
  glutSwapBuffers();
}

void display2(){
  glutSetWindow(secondWindow);
  glClearColor(0.0, 0.0, 0.0, 0.0);
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  glColor3f(1.0, 0.0, 0.0);

  glBegin(GL_POLYGON);
  glVertex3f(0.0, 0.0, 0.0);
  glVertex3f(0.5, 0.0, 0.0);
  glVertex3f(0.5, 0.5, 0.0);
  glVertex3f(0.0, 0.5, 0.0);
  glEnd();

  glutSwapBuffers();
  glFlush();
}

void reshape1(int w, int h){
  glutSetWindow(firstWindow);
  glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  display1();
}

void reshape2(int w, int h){
  glutSetWindow(secondWindow);
  glViewport(0, 0, (GLsizei) w, (GLsizei) h);
  display2();
}

int main(int argc, char* argv[]){
  glutInit(&argc,argv);
  glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowSize(300,100);
  glutInitWindowPosition(100, 100);
  firstWindow = glutCreateWindow("1st_window");
  glutReshapeFunc(reshape1);
  glutDisplayFunc(display1);

  glutInitWindowSize(300,100);
  glutInitWindowPosition(600, 100);
  secondWindow = glutCreateWindow("2nd_window");
  glutReshapeFunc(reshape2);
  glutDisplayFunc(display2);

  glutMainLoop();
  return 0;
}

piobair · 12-04-2023, 09:04 PM

So all that I needed to do was move the

Code:

glutDisplayFunc(display1);

up six lines. I tried that, and it works. Thank you
The original code snippet that I provided is over a decade old. I wonder why it never bombed before.

Quote:

Originally Posted by EdGr

The order matters.

You need to create the first window and set its reshape and display callbacks, and then create the second window and set its reshape and display callbacks.
Ed

EdGr · 12-05-2023, 09:37 AM

Quote:

Originally Posted by piobair

The original code snippet that I provided is over a decade old. I wonder why it never bombed before.

The library likely changed. This is an old-style API that relies on a global variable (the current window).
Ed