Smooth Shading in opengl - c

Question

I've been looking everywhere on how to do this and looked in the redbook of opengl and that only talks about smooth shading a 2d polygon. I'm not sure how you would do smooth shading for a glutSolidSphere. I know you have to do glShadeModel. and how can i tell the difference if its flat or smooth when there is no light for the scene.
#include <GLUT/glut.h>
#include <stdio.h>
#include <stdlib.h>
//Global variables
double sphere = 1, cone = 1, viewy = 2, viewx = -10, viewz = 5,headup = 5,headright = 5;
void myinit(){
glClearColor(0,0,0,1);
glShadeModel(GL_SMOOTH);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60,1,1,100);
//glOrtho(-2,20,-2,20,-10,10);
}
void drawRoom(){
//floor
glBegin(GL_POLYGON);
glColor3f(1,1,1);
glVertex3f(0,0,0);
glVertex3f(0,10,0);
glVertex3f(10,10,0);
glVertex3f(10,0,0);
glEnd(
);
//wall
glBegin(GL_POLYGON);
glColor3f(0,0,1);
glVertex3f(0,10,0);
glVertex3f(0,10,10);
glVertex3f(10,10,10);
glVertex3f(10,10,0);
glEnd();
//wall2
glBegin(GL_POLYGON);
glColor3f(0,1,0);
glVertex3f(10,10,0);
glVertex3f(10,10,10);
glVertex3f(10,0,10);
glVertex3f(10,0,0);
glEnd();
}
void drawObjects(){
//draw cone
glColor3f(1,0,1);
glTranslatef(2,2,0);
glutSolidCone(cone,5,10,2);
//draw sphere
glTranslatef(5,5,0);
glColor3f(1,0,0);
glutSolidSphere(sphere,500,500);
}
void move(unsigned char key, int x, int y){
switch(key){
case 'y':
viewy++;
glutPostRedisplay();
break;
case 'x':
viewx++;
glutPostRedisplay();
break;
case 'z':
viewz++;
glutPostRedisplay();
break;
//moves head
case 'd':
headup--;
headright--;
glutPostRedisplay();
break;
case 'a':
headup++;
headright++;
glutPostRedisplay();
break;
}
}
void display(){
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(viewx,viewy,viewz,headup,headright,5,0,0,1);
glClear(GL_COLOR_BUFFER_BIT);
drawRoom();
drawObjects();
glutSwapBuffers();
glFlush();
}
int main (int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowSize(500,500);
glutInitWindowPosition(100,100);
glutCreateWindow("Room");
myinit();
glutDisplayFunc(display);
glutKeyboardFunc(move);
glutMotionFunc(moveHead);
glutMainLoop();
return 0;
}

Answer 1

You need to enable lighting, enable at least one light, and supply differing per-vertex normals for your geometry to see the effects of GL_SMOOTH.
...how can i tell the difference if its flat or smooth when there is no light for the scene.
You can retrieve the current shading model via glGetIntegerv():
GLenum shadeModel;
glGetIntegerv( GL_SHADE_MODEL, &shadeModel );