Question

Last week, I tried a few examples I found while reading GLUT tutorials and everything was working great.

Now, when I retry those same examples, I get a weird behaviour: my GLUT window displays the part of the desktop that is at the place the window is (so if the GLUT window starts at (100,100) and is sized 500px by 500px, it displays the part of the desktop that starts at (100,100) and ends at (600,600)).

The following example that I tested last week should show a wire teapot on a black background. I’d like to know if there’s something wrong with my code (since I don’t recall changing anything in it) or if the problems come from the library not being linked correctly or if it’s something else that I’m not aware of.

#include <GL/glut.h>

void displayFunc(void);

int glutWindow;

int main(int argc, char** argv){
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);

    // define the size
    glutInitWindowSize(500,500);

    // the position where the window will appear
    glutInitWindowPosition(100,100);

    glutWindow = glutCreateWindow("UITest");
    glClearColor(0.0, 0.0, 0.0, 0.0);

    glutDisplayFunc(displayFunc);

    glutMainLoop();

    return EXIT_SUCCESS;
}

void displayFunc(void){
    glClear(GL_COLOR_BUFFER_BIT);

    glutWireTeapot(0.5);
}

Answer 1

You need to add a call to glFlush() in the end of displayFunc().