Aim:

Program, using OpenGL functions, to draw a simple shaded scene consisting of a tea pot on a table. Define suitably the position and properties of the light source along with the properties of the properties of the surfaces of the solid object used in the scene.

Algorithm:

1. Use function glutSolidCube() to draw wall and table
2. Use the same function to draw 4 cubes and then scale it in downward direction to make it look like tablelegs
3. glutSolidTeapot() is used to draw teapot

Code:

 //teapot.c
#include<stdio.h>
#include<GL/glut.h>
void wall(double thickness)
{
    glPushMatrix();
    glTranslated(0.5,0.5*thickness,0.5);
    glScaled(1.0,thickness,1.0);
    glutSolidCube(1.0);
    glPopMatrix();
}

void tableLeg(double thick,double len)
{
    glPushMatrix();
    glTranslated(0,len/2,0);
    glScaled(thick,len,thick);
    glutSolidCube(1.0);
    glPopMatrix();
}

void table(double topWid,double topThick,double legThick,double legLen)
{
    glPushMatrix();
    glTranslated(0,legLen,0);
    glScaled(topWid,topThick,topWid);
    glutSolidCube(1.0);
    glPopMatrix();
    double dist=0.95*topWid/2.0-legThick/2.0;
    glPushMatrix();
    glTranslated(dist,0,dist);
    tableLeg(legThick,legLen);
    glTranslated(0.0,0.0,-2*dist);
    tableLeg(legThick,legLen);
    glTranslated(-2*dist,0,2*dist);
    tableLeg(legThick,legLen);
    glTranslated(0,0,-2*dist);
    tableLeg(legThick,legLen);
    glPopMatrix();
}

void displaySolid(void)
{
    GLfloat mat_ambient[]={0.7f,0.7f,0.7f,1.0f};
    GLfloat mat_diffuse[]={0.5f,0.5f,0.5f,1.0f};
    GLfloat mat_specular[]={1.0f,1.0f,1.0f,1.0f};
    GLfloat mat_shininess[]={50.0f};

    //The glMaterialfv function specifies material parameters for the lighting model.
    glMaterialfv(GL_FRONT,GL_AMBIENT,mat_ambient);
    glMaterialfv(GL_FRONT,GL_DIFFUSE,mat_diffuse);
    glMaterialfv(GL_FRONT,GL_SPECULAR,mat_specular);
    glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess);
    GLfloat lightIntensity[]={0.7f,0.7f,0.7f,0.7f};
    GLfloat light_position[]={2.0f,6.0f,3.0f,0.0f};

    //The glLightfv function returns light source parameter values.
    glLightfv(GL_LIGHT0,GL_POSITION,light_position);
    glLightfv(GL_LIGHT0,GL_DIFFUSE,lightIntensity);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    double winHt=1.0;
    glOrtho(-winHt*64/48.0,winHt*64/48.0,-winHt,winHt,0.1,100.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(2.3,1.3,2.0,0.0,0.25,0.0,0.0,1.0,0.0);
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    glPushMatrix();
    glTranslated(0.4,0.4,0.6);
    glRotated(45,0,0,1);
    glScaled(0.08,0.08,0.08);
    glPopMatrix();
    glPushMatrix();
    glTranslated(0.6,0.38,0.5);
    glRotated(30,0,1,0);
    glutSolidTeapot(0.08);
    glPopMatrix();

    glPushMatrix();
    glTranslated(0.25,0.42,0.35);
    glPopMatrix();
    glPushMatrix();
    glTranslated(0.4,0,0.4);
    table(0.6,0.02,0.02,0.3);
    glPopMatrix();

    wall(0.02);
    glPushMatrix();
    glRotated(90.0,0.0,0.0,1.0);    //draw second wall after rotating x axis by 90degre
    wall(0.02);
    glPopMatrix();
    glPushMatrix();
    glRotated(-90.0,1.0,0.0,0.0);   //draw floor
    wall(0.02);
    glPopMatrix();
    glFlush();
}

int main(int argc,char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB|GLUT_DEPTH);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(100,100);
    glutCreateWindow("Simple shaded scene consisting of a teapot");
    glutDisplayFunc(displaySolid);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glShadeModel(GL_SMOOTH);//Specifies a symbolic value representing a shading technique. Accepted values are GL_FLAT and GL_SMOOTH.
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_NORMALIZE);
    glClearColor(0.1,0.1,0.1,0.0);
    glViewport(0,0,640,480);
    glutMainLoop();
}

Output:

Commands for execution:-

• Open a terminal and Change directory to the file location in both the terminals.
• compile as gcc -lGLU -lGL -lglut teapot.c -o teapot
• If no errors, run as ./teapot

Screenshots:-