To Apply shading to an object. Let's say earth (which was textured using an image). So how to apply smooth shading to that? What are the steps I need to write? Using which functions? Thank you.

To Apply shading to an object. Let's say earth (which was textured using an image). So how to apply smooth shading to that? What are the steps I need to write? Using which functions? Thank you.

Code

void drawScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindTexture(GL_TEXTURE_2D, textureOfSun);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glEnable(GL_TEXTURE_2D);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix(); // Push matrices

// Draw Sun

gluQuadricTexture(quadricSun,1);
gluSphere(quadricSun,2,20,20);
glPopMatrix();

//Draw Earth
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, textureOfEarth);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

//Rotation around Sun


//Revolve of Earth

glPopMatrix();
gluQuadricTexture(quadricEarth,1);
gluSphere(quadricEarth,0.75,20,20);

glutSwapBuffers();
}

This is the rendering part,

void initRendering() 
{
glEnable(GL_DEPTH_TEST);
glEnable(GL_NORMALIZE);
glEnable(GL_COLOR_MATERIAL);
quadricSun = gluNewQuadric();
quadricEarth = gluNewQuadric();

textureOfSun = LoadTexture(location1);
textureOfEarth = LoadTexture(location2); /* location1 and 2 says the locations of images */
}