I am trying to create a simple program that displays complex objects made of polygons. The problem that I am having is that the faces of objects dont appear to be drawn in the correct way, in that the faces that are behind front faces show through. I understand that the solution to this problem is Hidden surface removal, but I am having difficulty incorporating it into my program. Also if you know how, how would you orientate the camera via keys pressed by user-more specifically "gluLookat" I have tried to use the array at the top, but I am having difficulty. The code follows. Please feel free to modify the code, but I would appreciate "//" comments to indicate any changes. Thanks in advance for any help! Note that I am trying to create a closed cylinder, and that you have to rotate the model to see the problem. #include <gl/glut.h> #include <gl/glu.h> static left = 0, right = 0, up = 0, down = 0, spin =0, zoom = 0, shift = 0, turn = 0; static GLdouble viewer[]= {0.0, 0.0, 5.0}; GLUquadricObj *quadric; void Display ( void ) { quadric = gluNewQuadric(); gluQuadricNormals(quadric, GL_SMOOTH); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushMatrix(); //Rotate whole model glRotatef((GLfloat) spin,0.0,1.0,0.0); glRotatef((GLfloat) turn, 1.0, 0.0, 0.0); //Zomm in on model glTranslatef(0.0,0.0,(GLfloat) zoom); //Move whole model to left and right glTranslatef((GLfloat) shift,0.0,0.0); glColor3f(1.0,0.0,0.0); gluCylinder(quadric, 0.50, 0.50, 1, 35, 25); gluDisk(quadric, 0.0, 0.5, 35, 35); glPopMatrix(); glFlush(); glutSwapBuffers(); } void MyInit ( void ) { glClearColor (0.0, 0.0, 0.0, 0.0); glShadeModel (GL_SMOOTH); //glEnable(GL_DEPTH_TEST); glFrontFace(GL_CCW); glEnable(GL_CULL_FACE); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); ///////////////////////////////LIGHTING/////////////////////////// //variables GLfloat LightModelAmbient[] = {0.2, 0.2, 0.2, 1.0}; GLfloat light_position[] = {-2.0, 2.0, 2.0, 1.0}; GLfloat light_ambient[] = {0.0, 0.0, 0.0, 1.0}; GLfloat light_diffuse[] = {1.0, 1.0, 1.0, 1.0}; GLfloat light_spec[] = {1.0, 1.0, 1.0, 1.0}; GLfloat mat_ambi [] = {0.11, 0.06, 0.11, 1.0}; GLfloat mat_diff [] = {0.43, 0.47, 0.54, 1.0}; GLfloat mat_spec [] = {0.33, 0.33, 0.52, 1.0}; GLfloat mat_emis [] = {0.0, 0.0, 0.0, 0.0}; GLfloat mat_shin = 10.0; //lighting model commands glLightModelfv(GL_LIGHT_MODEL_AMBIENT, LightModelAmbient); glLightModelf(GL_LIGHT_MODEL_LOCAL_VIEWER, 0.0); glLightModelf(GL_LIGHT_MODEL_TWO_SIDE, 0.0); //lighting commands glLightfv(GL_LIGHT0, GL_POSITION, light_position); glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient); glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse); glLightfv(GL_LIGHT0, GL_SPECULAR, light_spec); //material commands glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambi); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diff); glMaterialfv(GL_FRONT, GL_SPECULAR, mat_spec); glMaterialfv(GL_FRONT, GL_EMISSION, mat_emis); glMaterialf(GL_FRONT, GL_SHININESS, mat_shin); } void Keys (unsigned char key, int xx, int yy) { if(key == 'r') { spin += -2; glutPostRedisplay(); } else if(key == 'R') { spin += 2; glutPostRedisplay(); } else if(key == 'z') { zoom += 1; glutPostRedisplay(); } else if(key == 'Z') { zoom += -1; glutPostRedisplay(); } else if(key == 'm') { shift += -2; glutPostRedisplay(); } else if(key == 'M') { shift += 2; glutPostRedisplay(); } else if (key == 'd') { zoom = 0; spin = 0; shift = 0; turn = 0; glutPostRedisplay(); } else if (key == 't') { turn += 2; glutPostRedisplay(); } else if (key == 'T') { turn -= 2; glutPostRedisplay(); } } void reshape (int w, int h) { glViewport (0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode (GL_PROJECTION); glLoadIdentity (); gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 0.0, 20.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); gluLookAt(viewer[0],viewer[1],viewer[2], 0.0, 0.0, 0.0,0.0, 1.0, 0.0); } int main(int argc, char **argv) { glutInit ( &argc, argv ) ; glutInitDisplayMode ( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH ) ; glutInitWindowSize ( 500,500 ) ; // window size glutInitWindowPosition ( 50, 50 ) ; // window position glutCreateWindow ( "Display sphere" ); MyInit ( ) ; glutDisplayFunc( Display); glutReshapeFunc(reshape); glutKeyboardFunc(Keys); glutMainLoop ( ) ; }

"Also if you know how, how would you orientate the camera via keys pressed by user- more specifically gLuLookat." reply: Tampering with gluLookat will significantly alter your lighting. I think the following method will better suit your purpose. It's an alternative to manipulating gluLookat. What you want to do is wrap this around your objects, then use the keyboard function to allow the user to manipulate the settings to view the scene from different angles and distance. TRY THIS! float scalex=1, scaley=1, scalez=1; int transx=0, transy=0, transz=0; int degreez=0, degreex=0, degreey=0, degree=0; //inside display function glPushMatrix(); glTranslatef(transx, transy, transz); glScalef(scalex, scaley, 1); glRotatef(degree, degreex, degreey, degreez); //draw your objects here glPopMatrix(); void keyboard (unsigned char key, int x, int y) { switch (key) { case 'x': scalex/=2; break; case 'X': scalex*=2; break; case 'y': scaley/=2; break; case 'Y': scaley*=2; break; case 'z': scalez/=2; break; case 'Z': scalez*=2; break; case 'u': transz-=1; break; case 'U': transz+=1; break; case 'l': transx-=2; break; case 'L': transx+=2; break; case 'r': transy-=3; break; case 'R': transy+=3; break; case 'A': degree+=10; degreez=1; degreey=0; degreex=0; break; case 'B': degree+=5; degreex=1; degreey=0; degreez=0; break; case 'C': degree+=20; degreey=1; degreex=0; degreez=0; break; default: break; } glutPostRedisplay(); } //This should work. If you're still interested in manipulating gluLookat, let me know. gluLookat is very sensitive. RadarSync-We drive you happy! (www.driversuneed.com)

Thankyou for your help, but I would prefer to use gluLookAt in conjunction with keys to alter the view.