gluLookAt with cone not showing expected result - opengl

Question

I am trying to look at a cone in 3D, for which I used gluLookAt. I draw a cone in the middle of the screen at pos (250, 250, 0) and then look at it with a camera above the origin looking at the middle. The output is a circle, contrary to the cone I expected to see. It seems the camera is instead at point (250,250,0) also, but it is specified in gluLookAt it should be above the origin. What am I overlooking here?
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(250, 250, 0);
glutSolidCone(30, 10, 20, 20);
glTranslatef(-250, -250, 0);
gluLookAt(0, 0, 100, 250, 250, 0, 0, 0, 1);
glFlush();
glutSwapBuffers();
}
int main(int argc, char **argv)
{
float x, y;
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(500, 500);
glutCreateWindow("Cone");
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMotionFunc(drag);
glutMouseFunc(click);
glutSpecialFunc(catchKey);
glEnable(GL_DEPTH_TEST);
glutMainLoop(); //calls do_one_simulation_step, keyboard, display, drag, reshape
return 0;
}

Answer 1

A few issues:
Set your camera matrix, then draw. The way you have it now your gluLookAt() does nothing useful.
The default identity projection matrix probably isn't what you want. Set a real perspective transform using gluPerspective() or glFrustum().
Your gluLookAt() eye/center coords were a bit wonky; I've put the eye at (50, 50, 50) and set it to look at the origin.
All together:
#include <GL/glut.h>
#include <GL/GLU.h>
void display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
double w = glutGet( GLUT_WINDOW_WIDTH );
double h = glutGet( GLUT_WINDOW_HEIGHT );
gluPerspective( 60.0, w / h, 1.0, 1000.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
gluLookAt( 50, 50, 50, 0, 0, 0, 0, 0, 1 );
glutWireCone( 10, 30, 20, 20 );
glutSwapBuffers();
}
int main( int argc, char **argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
glutInitWindowSize( 500, 500 );
glutCreateWindow( "Cone" );
glutDisplayFunc( display );
glEnable( GL_DEPTH_TEST );
glutMainLoop();
return 0;
}