Freeglut Reshape callback

Question

I am not using glutMainLoop() in my program but I am using glutMainLoopEvent() in a simple while loop. This is fine but the reshape callback is never called. I register my reshape event in the main(). Here's my source code:

#include <iostream>
#include "GL/freeglut.h"


float angle = 0.0f;


void ResizeEvent(int w, int h)
{
    std::cout << "Resizing... << w << " " << h << std::Endl;

    if(h == 0)
        h = 1;

    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0, (GLdouble)w / h, 0.1, 100.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void InitializeGL()
{
    glClearColor(0.0, 0.0, 0.0, 1.0f);
    glViewport(0, 0, 640, 480);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0, 640.0 / 480.0, 0.1, 100.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void Update()
{
    angle += 0.05f;
}

void Display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    glTranslatef(0.0f, 0.0f, -3.0f);
    glRotatef(angle, 0.5f, 1.0f, 0.75f);
    glBegin(GL_TRIANGLES);
        glColor3f(1.0f, 0.0f, 0.0f);
            glVertex3f(-1.0f, -1.0f, 0.0f);
        glColor3f(0.0f, 1.0f, 0.0f);
            glVertex3f(1.0f, -1.0f, 0.0f);
        glColor3f(0.0f, 0.0f, 1.0f);
            glVertex3f(0.0f, 1.0f, 0.0f);
    glEnd();

    glutSwapBuffers();
}

int main(int argc, char* argv[])
{
    glutInit(&argc, argv);
    glutInitWindowSize(640, 480);
    glutCreateWindow("Learning freeglut");

    InitializeGL();

    glutReshapeFunc(ResizeEvent);

    while(true)
    {
        Update();

        Display();

        glutMainLoopEvent();
    }

    return 0;
}

Thanks in advance!

Edit: Anyone?

Does the reshape function get called if you use glutMainLoop()? — Ben, Oct 06 '14 at 21:18
Yes. I try with other events like the keyboard event and it works with glutMainLoop and glutMainLoopEvent. — KrounNouns, Oct 06 '14 at 21:29

score 0 · Answer 1 · answered Nov 08 '14 at 18:54

glutReshapeFunc requires glutDisplayFunc to be set to something. This can even be an empty function as long as you don't need the window to update while resizing.

Possible solution

    ...

    glutReshapeFunc(ResizeEvent);

    glutDisplayFunc(Display);

    while(true)
    {
        Update();

        Display();

        glutMainLoopEvent();
    }

    ...

Freeglut Reshape callback

1 Answers1