3D Primitives with OpenGL(DA1)

3D Primitives with OpenGL

OpenGL is mainly considered an API (an Application Programming Interface) that provides us with a large set of functions that we can use to manipulate graphics and images. However, OpenGL by itself is not an API, but merely a specification, developed and maintained by the Khronos Group.

The OpenGL specification specifies exactly what the result/output of each function should be and how it should perform. It is then up to the developers implementing this specification to come up with a solution of how this function should operate. Since the OpenGL specification does not give us implementation details, the actual developed versions of OpenGL are allowed to have different implementations, as long as their results comply with the specification (and are thus the same to the user).

Output Screenshots:

Code:

#include <GL\glut.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>
using namespace std;

GLfloat xAngle, yAngle, zAngle;
GLdouble radius = 1, side = 1, b_radius = 1, height = 3, inner_radius = 1, outer_radius = 2;
int option;

void display(void);
void reshape(int x, int y);

void get_key(unsigned char key, int x, int y) {
    option = int(key) - int('0');
    switch (option) {
    case 1:
        cout << "You have chosen Sphere\nEnter radius:";
        cin >> radius;
        cout << "\n";
        break;
    case 2:
        cout << "YOu have chosen Cube\nEnter side length: ";
        cin >> side;
        cout << "\n";
        break;
    case 3:
        cout << "You have chose Cone\nEnter base radius: ";
        cin >> b_radius;
        cout << "Enter height: ";
        cin >> height;
        cout << "\n";
        break;
    case 4:
        cout << "You have chosen Torus\nEnter inner radius: ";
        cin >> inner_radius;
        cout << "Enter outer radius: ";
        cin >> outer_radius;
        cout << "\n";
        break;

    }
}
void idle(void)
{
    xAngle += 0.01;
    yAngle += 0.01;
    zAngle += 0.01;
    display();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitWindowPosition(350, 350);
    glutInitWindowPosition(500, 500);
    glutCreateWindow("3D Primitives in OpenGl");
    xAngle = yAngle = zAngle = 0;
    cout << "Enter option\n1.Sphere\n2.Cube\n3.Cone\n4.Torus\n5.Dodecahedron\n6.Octahedron\n7.Tetrahedron";
    cin >> option;
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutKeyboardFunc(get_key);
    glutIdleFunc(idle);
    glutMainLoop();
    return 0;
}

void display(void)
{
    //initalize
    glMatrixMode(GL_MODELVIEW);
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();

    //object depth
    glTranslatef(0.0, 0.0, -3.0);

    //changing transformation matrix
    //rotation about X aixs
    glRotatef(xAngle, 1.0, 0.0, 0.0);
    //Y axis
    glRotatef(yAngle, 0.0, 1.0, 0.0);
    //Z axis
    glRotatef(zAngle, 0.0, 0.0, 1.0);
    //scaling
    glScalef(1.0, 1.0, 1.0);
    switch (option) {
    case 1:
        glutWireSphere(radius, 10, 10);
        break;
    case 2:
        glutWireCube(side);
        break;
    case 3:
        glutWireCone(b_radius, height, 10, 10);
        break;
    case 4:
        glutWireTorus(inner_radius, outer_radius, 10, 10);
        break;
    case 5:
        glutWireDodecahedron();
        break;
    case 6:
        glutWireOctahedron();
        break;
    case 7:
        glutWireTetrahedron();
        break;
    case 0:
        cout << "Exit\n";
        return;
    }
    glFlush();
}

void reshape(int x, int y)
{
    if (y == 0 || x == 0) return;
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(120, (GLdouble)x / (GLdouble)y, 0.6, 21.0);
    glMatrixMode(GL_MODELVIEW);
    glViewport(0, 0, x, y);
}