glulookat() - move camera with keyboard( OpenGL) - c++

Question

I am trying to move the camera with the use of the keyboard. I am calling the glulookat function in the draw method as follows:
gluLookAt(posx,posy,posz,lookx,looky,lookz,upx,upy,upz);
Also I have, for example, for moving the position of the camera on the X axis the following code:
void keyboard(unsigned char key, int x, int y) {
switch(key) {
case 'w' :
break;
case 'a' :
posx-=1.0;
break;
case 's' :
break;
case 'd' :
posx+=1.0;
break;
}
}
The posx,posy,posz,lookx,looky,lookz,upx,upy,upz variables are declared as global double variables. I have tried to initialize them in two ways: when declaring them, as well as in the init() method, but with no success. The camera isn't moving, although the program receives the keyboard input properly, as I have tested this aspect separately. Any ideas of what I am doing wrong?
EDIT: I provided the main code for a better understanding:
Outer_space* space;
Light* sceneLight;
Light* sceneLight2;
Light* sceneLight3;
Satelite* satelite1;
double posx=35.0,posy=35.0,posz=35.0,lookx=0,looky=1,lookz=0,upx=0,upy=0,upz=-1;
void init(void) {
//random number generator
srand(time(NULL));
space = new Outer_space(12, 12,12, new Vector3D(0.5f, 0.7f, 0.9f));
sceneLight = new Light(0, 0);
sceneLight->setTranslation(new Vector3D(0, 20, 0));
sceneLight->setConstantAttenuation(0.09f);
sceneLight->setLinearAttenuation(0.08f);
sceneLight2 = new Light(1, 0);
sceneLight2->setTranslation(new Vector3D(20, 0, 0));
sceneLight2->setConstantAttenuation(0.09f);
sceneLight2->setLinearAttenuation(0.08f);
sceneLight3 = new Light(2, 0);
sceneLight3->setTranslation(new Vector3D(0, 0, 20));
sceneLight3->setConstantAttenuation(0.09f);
sceneLight3->setLinearAttenuation(0.08f);
satelite1 = new Satelite(2,new Vector3D(0.2f,0.3f,0.5f));
satelite1->setTranslation(new Vector3D(10,10,10));
satelite1->setRotation(new Vector3D(-90, 0, 0));
satelite1->setScale(new Vector3D(10, 10, 10));
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glEnable(GL_DEPTH_TEST);
glShadeModel(GL_SMOOTH);
glEnable(GL_LIGHTING);
glEnable(GL_NORMALIZE);
}
void draw(void) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
//gluLookAt(0,20,0, 0, 0, 0, 0, 1, 0);
gluLookAt(posx,posy,posz,lookx,looky,lookz,upx,upy,upz);
space->draw();
sceneLight->draw();
sceneLight2->draw();
sceneLight3->draw();
satelite1->draw();
glPushMatrix();
glRasterPos3f(-8.5, 4, -6);
glutSwapBuffers();
}
void update(void){
glutPostRedisplay();
}
void resize(int w, int h) {
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
GLfloat aspect = (GLfloat)w / (GLfloat)h;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45, aspect, 1.0, 60);
}
void keyboard(unsigned char key, int x, int y) {
switch (key)
{
case 'w' :
break;
case 'a' :
posx-=1.0;
break;
case 's' :
break;
case 'd' :
posx+=1.0;
break;
}
}
void specialKeyboard(int key, int x, int y) {
switch (key)
{
case GLUT_KEY_RIGHT:
posx+=1;
break;
case GLUT_KEY_LEFT:
posx-=1;
break;
case GLUT_KEY_UP:
break;
case GLUT_KEY_DOWN:
break;
}
}
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(800, 600);
glutInitWindowPosition(100, 100);
glutCreateWindow("Asteroid Escape");
init();
glutIdleFunc(update);
glutDisplayFunc(draw);
glutReshapeFunc(resize);
glutKeyboardFunc(keyboard);
glutSpecialFunc(specialKeyboard);
glutMainLoop();
return 0;
}
EDIT2:
I have commented out the glPushMatrix(); call from the draw() method and now the camera seems to be moving. What is the explanation?

Answer 1

glPushMatrix is supposed to be followed by glPopMatrix.
It seems that you overflow the matrix stack, did you check glGetError result ?
Besides, jour call to glPushMatrix seems pretty useless like this, what do you expect it to do ?