/////////////////////////////////// // square.cpp // // OpenGL program to draw a square. // // Sumanta Guha. /////////////////////////////////// #include <GL/freeglut.h> #include <cmath> #define PI 3.14 void drawDisc(float R, float X, float Y, float Z) { static int N = 100; // #vertices. float t = 0.0; glBegin(GL_LINE_LOOP); for (int i = 0; i <= N; ++i) { glVertex3f(X + R * cos(t), Y + R * sin(t), Z); t += 2 * PI / N; } glEnd(); } void drawDiamond() { glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); glVertex3f(50, 26, 0); glVertex3f(56, 20, 0); glVertex3f(50, 14, 0); glVertex3f(44, 20, 0); glEnd(); } void drawCoss() { glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); glVertex3f(73, 51, 0); glVertex3f(85, 51, 0); glVertex3f(85, 49, 0); glVertex3f(73, 49, 0); glEnd(); glBegin(GL_POLYGON); glVertex3f(78, 56, 0); glVertex3f(80, 56, 0); glVertex3f(80, 44, 0); glVertex3f(78, 44, 0); glEnd(); } void drawTriangle() { glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); glVertex3f(50, 86, 0); glVertex3f(56, 74, 0); glVertex3f(44, 74, 0); glEnd(); } void drawArrow() { glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); glVertex3f(50, 68, 0); glVertex3f(44, 63, 0); glVertex3f(56, 63, 0); glEnd(); glBegin(GL_POLYGON); glVertex3f(46, 63, 0); glVertex3f(54, 63, 0); glVertex3f(54, 32, 0); glVertex3f(46, 32, 0); glEnd(); } void drawPiont(float R, float X, float Y, float Z) { static int N = 200; // #vertices. float t = 0.0; glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); glBegin(GL_TRIANGLE_FAN); glVertex3f(X, Y, 0); //center point for (int i = 0; i < N + 1; i++) { glVertex3f(X + R * cos(t), Y + R * sin(t), 0.0); t += 2 * PI / N; } glEnd(); } void drawStar() { glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); glVertex3f(15, 51, 0); glVertex3f(27, 51, 0); glVertex3f(21, 46, 0); glEnd(); glBegin(GL_POLYGON); glVertex3f(21, 56, 0); glVertex3f(21, 46, 0); glVertex3f(17, 44, 0); glEnd(); glBegin(GL_POLYGON); glVertex3f(21, 56, 0); glVertex3f(21, 46, 0); glVertex3f(25, 44, 0); glEnd(); } // Drawing routine. void drawScene(void) { glClear(GL_COLOR_BUFFER_BIT); //glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //glEnable(GL_DEPTH_TEST); glColor3ub(190, 190, 190); for (float i = 0; i < 400; i++) { float n = i * 0.01; drawDisc(42.0-n, 50.0, 50.0, 0.0); i += i * 0.01; } glColor3ub(225, 225, 0); drawDiamond(); glColor3ub(255, 0, 0); drawCoss(); glColor3ub(65, 105, 225); drawTriangle(); glColor3ub(205, 104, 57); drawArrow(); glColor3f(0, 0, 0); drawPiont(1, 50.0, 50.0, 0.0); glColor3ub(50, 205, 50); drawStar(); //glDisable(GL_DEPTH_TEST); glFlush(); } // Initialization routine. void setup(void) { glClearColor(1.0, 1.0, 1.0, 0.0); } ...

1. ///////////////////////////////////
// square.cpp
//
// OpenGL program to draw a square.
//
// Sumanta Guha.
///////////////////////////////////
#include <GL/freeglut.h>
#include <cmath>
#define PI 3.14
void drawDisc(float R, float X, float Y, float Z) {
static int N = 100; // #vertices.
float t = 0.0;
glBegin(GL_LINE_LOOP);

2. for (int i = 0; i <= N; ++i) {
glVertex3f(X + R * cos(t), Y + R * sin(t), Z);
t += 2 * PI / N;
}
glEnd();
}
void drawDiamond() {
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBegin(GL_POLYGON);
glVertex3f(50, 26, 0);
glVertex3f(56, 20, 0);
glVertex3f(50, 14, 0);
glVertex3f(44, 20, 0);
glEnd();
}

3. void drawCoss() {
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBegin(GL_POLYGON);
glVertex3f(73, 51, 0);
glVertex3f(85, 51, 0);
glVertex3f(85, 49, 0);
glVertex3f(73, 49, 0);
glEnd();
glBegin(GL_POLYGON);
glVertex3f(78, 56, 0);
glVertex3f(80, 56, 0);
glVertex3f(80, 44, 0);
glVertex3f(78, 44, 0);
glEnd();
}
void drawTriangle() {

4. glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBegin(GL_POLYGON);
glVertex3f(50, 86, 0);
glVertex3f(56, 74, 0);
glVertex3f(44, 74, 0);
glEnd();
}
void drawArrow() {
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBegin(GL_POLYGON);
glVertex3f(50, 68, 0);
glVertex3f(44, 63, 0);
glVertex3f(56, 63, 0);
glEnd();
glBegin(GL_POLYGON);
glVertex3f(46, 63, 0);
glVertex3f(54, 63, 0);

5. glVertex3f(54, 32, 0);
glVertex3f(46, 32, 0);
glEnd();
}
void drawPiont(float R, float X, float Y, float Z) {
static int N = 200; // #vertices.
float t = 0.0;
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glBegin(GL_TRIANGLE_FAN);
glVertex3f(X, Y, 0); //center point
for (int i = 0; i < N + 1; i++)
{
glVertex3f(X + R * cos(t), Y + R * sin(t), 0.0);
t += 2 * PI / N;
}
glEnd();
}

6. void drawStar() {
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBegin(GL_POLYGON);
glVertex3f(15, 51, 0);
glVertex3f(27, 51, 0);
glVertex3f(21, 46, 0);
glEnd();
glBegin(GL_POLYGON);
glVertex3f(21, 56, 0);
glVertex3f(21, 46, 0);
glVertex3f(17, 44, 0);
glEnd();
glBegin(GL_POLYGON);
glVertex3f(21, 56, 0);
glVertex3f(21, 46, 0);
glVertex3f(25, 44, 0);
glEnd();

7. }
// Drawing routine.
void drawScene(void)
{
glClear(GL_COLOR_BUFFER_BIT);
//glClear(GL_COLOR_BUFFER_BIT |
GL_DEPTH_BUFFER_BIT);
//glEnable(GL_DEPTH_TEST);
glColor3ub(190, 190, 190);
for (float i = 0; i < 400; i++) {
float n = i * 0.01;
drawDisc(42.0-n, 50.0, 50.0, 0.0);
i += i * 0.01;
}

8. glColor3ub(225, 225, 0);
drawDiamond();
glColor3ub(255, 0, 0);
drawCoss();
glColor3ub(65, 105, 225);
drawTriangle();
glColor3ub(205, 104, 57);
drawArrow();
glColor3f(0, 0, 0);
drawPiont(1, 50.0, 50.0, 0.0);
glColor3ub(50, 205, 50);
drawStar();

9. //glDisable(GL_DEPTH_TEST);
glFlush();
}
// Initialization routine.
void setup(void)
{
glClearColor(1.0, 1.0, 1.0, 0.0);
}
// OpenGL window reshape routine.
void resize(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

10. glOrtho(0.0, 100.0, 0.0, 100.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
// Keyboard input processing routine.
void keyInput(unsigned char key, int x, int y)
{
switch (key)
{
case 27:
exit(0);
break;
default:
break;
}
}

11. // g++ -framework OpenGL -lGLUT -lGLEW -I
/opt/X11/include -L /opt/X11/lib -w -o out squareEx.cpp
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitContextVersion(4, 3);
glutInitContextProfile(GLUT_COMPATIBILITY_PROFIL
E);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
//glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA |
GLUT_DEPTH);
glutInitWindowSize(500, 500);
glutInitWindowPosition(100, 100);
glutCreateWindow("square.cpp");

12. glutDisplayFunc(drawScene);
glutReshapeFunc(resize);
glutKeyboardFunc(keyInput);
setup();
glutMainLoop();
}