glutMouseWheelFunc doesnt trigger callback - opengl

Question

I am trying to implement zoom in or zoom out operations using mouse scroll button
by glutMouseWheelFunc in opengl . I have implemted the code as below :
#include<GL/freeglut.h>
void mouseWheel(int button, int dir, int x, int y)
{
printf("in mouse wheel \n");
if (dir > 0)
{
// Zoom in
ztrans = ztrans - 1.0;
printf("scroll in = %0.3f\n ",ztrans);
}
else
{
// Zoom out
ztrans = ztrans + 1.0;
printf("scroll out = %0.3f\n ",ztrans);
}
glutPostRedisplay();
}
int main(int argc, char **argv)
{
// general initializations
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100, 100);
glutInitWindowSize(800, 400);
glutCreateWindow("Rotation");
// register callbacks
glutReshapeFunc(changeSize);
glutDisplayFunc(renderScene);
glutIdleFunc(renderScene);
glutIgnoreKeyRepeat(1);
glutMouseFunc(mouseButton);
glutMotionFunc(mouseMove);
glutMouseWheelFunc(mouseWheel); // Register mouse wheel function
glEnable(GL_DEPTH_TEST);
glutMainLoop();
return 0;
}
On executing, it is not calling the registered callback function(mouseWheel) . My system has freeglut3 installed.

Answer 1

try using
a static int inside void mouseWheelmethod, and then use it in renderScene
like this
static int k;
static int ztrans
void mouseWheel(int button, int dir, int x, int y)
{
k = dir; // int dir is +1 of -1 based on the direction of the wheel motion
ztrans = ztrans + k;
}
This worked for me,
Try this and feedback, GoodLuck .