#include <stdlib.h>
#include <math.h>#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif// angle of rotation for the camera direction
float angle = 0.0f;// actual vector representing the camera's direction
float lx=0.0f,lz=-1.0f;// XZ position of the camera
float x=0.0f, z=5.0f;// the key states. These variables will be zero
//when no key is being presses
float deltaAngle = 0.0f;
float deltaMove = 0;
int xOrigin = -1;// Constant definitions for Menus
#define RED 1
#define GREEN 2
#define BLUE 3
#define ORANGE 4#define FILL 1
#define LINE 2#define SHRINK 1
#define NORMAL 2// Pop up menu identifiers
int fillMenu, shrinkMenu, mainMenu, colorMenu;// color for the nose
float red = 1.0f, blue=0.5f, green=0.5f;// scale of snowman
float scale = 1.0f;// menu status
int menuFlag = 0;void changeSize(int w, int h) {// Prevent a divide by zero, when window is too short// (you cant make a window of zero width).if (h == 0)h = 1;float ratio =  w * 1.0 / h;// Use the Projection Matrix
    glMatrixMode(GL_PROJECTION);// Reset Matrix
    glLoadIdentity();// Set the viewport to be the entire windowglViewport(0, 0, w, h);// Set the correct perspective.gluPerspective(45.0f, ratio, 0.1f, 100.0f);// Get Back to the Modelview
    glMatrixMode(GL_MODELVIEW);
}void drawSnowMan() {glScalef(scale, scale, scale);glColor3f(1.0f, 1.0f, 1.0f);// Draw BodyglTranslatef(0.0f ,0.75f, 0.0f);glutSolidSphere(0.75f,20,20);// Draw HeadglTranslatef(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(red, green, blue);glRotatef(0.0f,1.0f, 0.0f, 0.0f);glutSolidCone(0.08f,0.5f,10,2);glColor3f(1.0f, 1.0f, 1.0f);
}void computePos(float deltaMove) {x += deltaMove * lx * 0.1f;z += deltaMove * lz * 0.1f;
}void renderScene(void) {if (deltaMove)computePos(deltaMove);// Clear Color and Depth BuffersglClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);// Reset transformations
    glLoadIdentity();// Set the cameragluLookAt(    x, 1.0f, z,x+lx, 1.0f,  z+lz,0.0f, 1.0f,  0.0f);// 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 SnowMenfor(int i = -3; i < 3; i++)for(int j=-3; j < 3; j++) {glPushMatrix();glTranslatef(i*10.0f, 0.0f, j * 10.0f);drawSnowMan();glPopMatrix();}glutSwapBuffers();
}// -----------------------------------
//             KEYBOARD
// -----------------------------------void processNormalKeys(unsigned char key, int xx, int yy) {glutSetMenu(mainMenu);switch (key) {case 27:glutDestroyMenu(mainMenu);glutDestroyMenu(fillMenu);glutDestroyMenu(colorMenu);glutDestroyMenu(shrinkMenu);exit(0);break;case 's':if (!menuFlag)glutChangeToSubMenu(2,"Shrink",shrinkMenu);break;case 'c':if (!menuFlag)glutChangeToSubMenu(2,"Color",colorMenu);break;}if (key == 27)exit(0);
}void pressKey(int key, int xx, int yy) {switch (key) {case GLUT_KEY_UP : deltaMove = 0.5f; break;case GLUT_KEY_DOWN : deltaMove = -0.5f; break;}
}void releaseKey(int key, int x, int y) {switch (key) {case GLUT_KEY_UP :case GLUT_KEY_DOWN : deltaMove = 0;break;}
}// -----------------------------------
//             MOUSE
// -----------------------------------void mouseMove(int x, int y) {// this will only be true when the left button is downif (xOrigin >= 0) {// update deltaAngledeltaAngle = (x - xOrigin) * 0.001f;// update camera's directionlx = sin(angle + deltaAngle);lz = -cos(angle + deltaAngle);}
}void mouseButton(int button, int state, int x, int y) {// only start motion if the left button is pressedif (button == GLUT_LEFT_BUTTON) {// when the button is releasedif (state == GLUT_UP) {angle += deltaAngle;xOrigin = -1;}else  {// state = GLUT_DOWNxOrigin = x;}}
}// -----------------------------------
//             MENUS
// -----------------------------------void processMenuStatus(int status, int x, int y) {if (status == GLUT_MENU_IN_USE)menuFlag = 1;elsemenuFlag = 0;
}void processMainMenu(int option) {// nothing to do in here// all actions are for submenus
}void processFillMenu(int option) {switch (option) {case FILL: glPolygonMode(GL_FRONT, GL_FILL); break;case LINE: glPolygonMode(GL_FRONT, GL_LINE); break;}
}void processShrinkMenu(int option) {switch (option) {case SHRINK: scale = 0.5f; break;case NORMAL: scale = 1.0f; break;}
}void processColorMenu(int option) {switch (option) {case RED :red = 1.0f;green = 0.0f;blue = 0.0f; break;case GREEN :red = 0.0f;green = 1.0f;blue = 0.0f; break;case BLUE :red = 0.0f;green = 0.0f;blue = 1.0f; break;case ORANGE :red = 1.0f;green = 0.5f;blue = 0.5f; break;}
}void createPopupMenus() {shrinkMenu = glutCreateMenu(processShrinkMenu);glutAddMenuEntry("Shrink",SHRINK);glutAddMenuEntry("NORMAL",NORMAL);fillMenu = glutCreateMenu(processFillMenu);glutAddMenuEntry("Fill",FILL);glutAddMenuEntry("Line",LINE);colorMenu = glutCreateMenu(processColorMenu);glutAddMenuEntry("Red",RED);glutAddMenuEntry("Blue",BLUE);glutAddMenuEntry("Green",GREEN);glutAddMenuEntry("Orange",ORANGE);mainMenu = glutCreateMenu(processMainMenu);glutAddSubMenu("Polygon Mode", fillMenu);glutAddSubMenu("Color", colorMenu);// attach the menu to the right button
    glutAttachMenu(GLUT_RIGHT_BUTTON);// this will allow us to know if the menu is active
    glutMenuStatusFunc(processMenuStatus);
}// -----------------------------------
//             MAIN
// -----------------------------------int main(int argc, char **argv) {// init GLUT and create windowglutInit(&argc, argv);glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);glutInitWindowPosition(100,100);glutInitWindowSize(320,320);glutCreateWindow("Lighthouse3D - GLUT Tutorial");// register callbacks
    glutDisplayFunc(renderScene);glutReshapeFunc(changeSize);glutIdleFunc(renderScene);glutIgnoreKeyRepeat(1);glutKeyboardFunc(processNormalKeys);glutSpecialFunc(pressKey);glutSpecialUpFunc(releaseKey);// here are the two new functions
    glutMouseFunc(mouseButton);glutMotionFunc(mouseMove);// OpenGL init
    glEnable(GL_DEPTH_TEST);glEnable(GL_CULL_FACE);// init Menus
    createPopupMenus();// enter GLUT event processing cycle
    glutMainLoop();return 1;
}