Drawing a snowman using OpenGL source code

This source code is written in c using the OpenGL library. This program is just a demo to draw a different shape object and I draw a man like an object in this program. I have also added a keyboard event in this program.

#include <math.h>
#include <GL/glut.h>
#include <stdio.h>
#include <string.h>
//#include <cstdlib>
//if you got error in exit() by compiler then does not incluede stdlib.h because //exit() is also defined in glut.h file.

float angle=0.0,deltaAngle = 0.0,ratio;
float x=0.0f,y=1.75f,z=5.0f;
float lx=0.0f,ly=0.0f,lz=-1.0f;
int deltaMove = 0,h,w;
int font=(int)GLUT_BITMAP_8_BY_13;
static GLint snowman_display_list;
int bitmapHeight=13;

int frame,time,timebase=0;
char s[30];

void initWindow();

void changeSize(int w1, int h1)
{

// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if(h1 == 0)
h1 = 1;

w = w1;
h = h1;
ratio = 1.0f * w / h;
// Reset the coordinate system before modifying
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

// Set the viewport to be the entire window
    glViewport(0, 0, w, h);

// Set the clipping volume
gluPerspective(45,ratio,0.1,1000);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(x, y, z,
     x + lx,y + ly,z + lz,
 0.0f,1.0f,0.0f);


}




void drawSnowMan() {


glColor3f(1.0f, 1.0f, 1.0f);

// Draw Body
glTranslatef(0.0f ,0.75f, 0.0f);
glutSolidSphere(0.75f,20,20);


// Draw Head
glTranslatef(0.0f, 1.0f, 0.0f);
glutSolidSphere(0.25f,20,20);

// Draw Eyes
glPushMatrix();
glColor3f(0.0f,0.0f,0.0f);
glTranslatef(0.05f, 0.10f, 0.18f);
glutSolidSphere(0.05f,10,10);
glTranslatef(-0.1f, 0.0f, 0.0f);
glutSolidSphere(0.05f,10,10);
glPopMatrix();

// Draw Nose
glColor3f(1.0f, 0.5f , 0.5f);
glRotatef(0.0f,1.0f, 0.0f, 0.0f);
glutSolidCone(0.08f,0.5f,10,2);
}



GLuint createDL() {
GLuint snowManDL;

// Create the id for the list
snowManDL = glGenLists(2);

glNewList(snowManDL+1,GL_COMPILE);
drawSnowMan();
glEndList();
// start list
glNewList(snowManDL,GL_COMPILE);

// call the function that contains the rendering commands
for(int i = -3; i < 3; i++)
for(int j=-3; j < 3; j++) {
glPushMatrix();
glTranslatef(i*10.0,0,j * 10.0);
glCallList(snowManDL+1);
glPopMatrix();
}

// endList
glEndList();

return(snowManDL);
}

void initScene() {

glEnable(GL_DEPTH_TEST);
snowman_display_list = createDL();

}

void orientMe(float ang) {


lx = sin(ang);
lz = -cos(ang);
glLoadIdentity();
gluLookAt(x, y, z,
     x + lx,y + ly,z + lz,
 0.0f,1.0f,0.0f);
}


void moveMeFlat(int i) {
x = x + i*(lx)*0.1;
z = z + i*(lz)*0.1;
glLoadIdentity();
gluLookAt(x, y, z,
     x + lx,y + ly,z + lz,
 0.0f,1.0f,0.0f);
}

void setOrthographicProjection() {

// switch to projection mode
glMatrixMode(GL_PROJECTION);
// save previous matrix which contains the
//settings for the perspective projection
glPushMatrix();
// reset matrix
glLoadIdentity();
// set a 2D orthographic projection
gluOrtho2D(0, w, 0, h);
// invert the y axis, down is positive
glScalef(1, -1, 1);
// mover the origin from the bottom left corner
// to the upper left corner
glTranslatef(0, -h, 0);
glMatrixMode(GL_MODELVIEW);
}

void resetPerspectiveProjection() {
// set the current matrix to GL_PROJECTION
glMatrixMode(GL_PROJECTION);
// restore previous settings
glPopMatrix();
// get back to GL_MODELVIEW matrix
glMatrixMode(GL_MODELVIEW);
}

void renderBitmapString(float x, float y, void *font,char *string)
{

  char *c;
  // set position to start drawing fonts
  glRasterPos2f(x, y);
  // loop all the characters in the string
  for (c=string; *c != '\0'; c++) {
    glutBitmapCharacter(font, *c);
  }
}


void renderScene(void) {

if (deltaMove)
moveMeFlat(deltaMove);
if (deltaAngle) {
angle += deltaAngle;
orientMe(angle);
}

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Draw ground

glColor3f(0.9f, 0.9f, 0.9f);
glBegin(GL_QUADS);
glVertex3f(-100.0f, 0.0f, -100.0f);
glVertex3f(-100.0f, 0.0f,  100.0f);
glVertex3f( 100.0f, 0.0f,  100.0f);
glVertex3f( 100.0f, 0.0f, -100.0f);
glEnd();

// Draw 36 Snow Men

glCallList(snowman_display_list);

frame++;
time=glutGet(GLUT_ELAPSED_TIME);
if (time - timebase > 1000) {
sprintf(s,"FPS:%4.2f",frame*1000.0/(time-timebase));
timebase = time;
frame = 0;
}

glColor3f(0.0f,1.0f,1.0f);
setOrthographicProjection();
glPushMatrix();
glLoadIdentity();
renderBitmapString(30,15,(void *)font,"GLUT Tutorial @ 3D Tech");
renderBitmapString(30,35,(void *)font,s);
renderBitmapString(30,55,(void *)font,"Esc - Quit");
glPopMatrix();
resetPerspectiveProjection();

glutSwapBuffers();
}

void processNormalKeys(unsigned char key, int x, int y) {

if (key == 27)
exit(0);
}

void pressKey(int key, int x, int y) {

switch (key) {
case GLUT_KEY_LEFT : deltaAngle = -0.01f;break;
case GLUT_KEY_RIGHT : deltaAngle = 0.01f;break;
case GLUT_KEY_UP : deltaMove = 1;break;
case GLUT_KEY_DOWN : deltaMove = -1;break;
}

}

void releaseKey(int key, int x, int y) {

switch (key) {
case GLUT_KEY_LEFT : if (deltaAngle < 0.0f)
deltaAngle = 0.0f;
break;
case GLUT_KEY_RIGHT : if (deltaAngle > 0.0f)
deltaAngle = 0.0f;
break;
case GLUT_KEY_UP : if (deltaMove > 0)
deltaMove = 0;
break;
case GLUT_KEY_DOWN : if (deltaMove < 0)
deltaMove = 0;
break;
}
}

void initWindow() {
glutIgnoreKeyRepeat(1);
glutKeyboardFunc(processNormalKeys);
glutSpecialFunc(pressKey);
glutSpecialUpFunc(releaseKey);
glutDisplayFunc(renderScene);
glutIdleFunc(renderScene);
glutReshapeFunc(changeSize);
initScene();

}

int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100,100);
glutInitWindowSize(640,360);
glutCreateWindow("codeincodeblock.blogspot.com");

// register all callbacks
initWindow();

glutMainLoop();

return(0);
}