/* cubeview.c          */

/* E. Angel, Interactive Computer Graphics */
/* A Top-Down Approach with OpenGL, Third Edition */
/* Addison-Wesley Longman, 2003 *//* Rotating cube with viewer movement from Chapter 5 *//* Cube definition and display similar to rotating--cube program *//* We use the Lookat function in the display callback to pointthe viewer, whose position can be altered by the x,X,y,Y,z, and Z keys.The perspective view is set in the reshape callback */#include <stdlib.h>#include <GL/glut.h>	GLfloat vertices[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0},	{1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0}, 	{1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}};	GLfloat normals[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0},	{1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0}, 	{1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}};	GLfloat colors[][3] = {{0.0,0.0,0.0},{1.0,0.0,0.0},	{1.0,1.0,0.0}, {0.0,1.0,0.0}, {0.0,0.0,1.0}, 	{1.0,0.0,1.0}, {1.0,1.0,1.0}, {0.0,1.0,1.0}};void polygon(int a, int b, int c , int d){	glBegin(GL_POLYGON);		glColor3fv(colors[a]);		glNormal3fv(normals[a]);		glVertex3fv(vertices[a]);		glColor3fv(colors[b]);		glNormal3fv(normals[b]);		glVertex3fv(vertices[b]);		glColor3fv(colors[c]);		glNormal3fv(normals[c]);		glVertex3fv(vertices[c]);		glColor3fv(colors[d]);		glNormal3fv(normals[d]);		glVertex3fv(vertices[d]);	glEnd();																										}void colorcube(){	polygon(0,3,2,1);	polygon(2,3,7,6);	polygon(0,4,7,3);	polygon(1,2,6,5);	polygon(4,5,6,7);	polygon(0,1,5,4);}static GLfloat theta[] = {0.0,0.0,0.0};static GLint axis = 2;static GLdouble viewer[]= {0.0, 0.0, 5.0}; /* initial viewer location */void display(void){ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);/* Update viewer position in modelview matrix */	glLoadIdentity();	gluLookAt(viewer[0],viewer[1],viewer[2], 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);/* rotate cube */	glRotatef(theta[0], 1.0, 0.0, 0.0);	glRotatef(theta[1], 0.0, 1.0, 0.0);	glRotatef(theta[2], 0.0, 0.0, 1.0); colorcube(); glFlush();	glutSwapBuffers();}void mouse(int btn, int state, int x, int y){	if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;	if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;	if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;	theta[axis] += 2.0;	if( theta[axis] > 360.0 ) theta[axis] -= 360.0;	display();}void keys(unsigned char key, int x, int y){/* Use x, X, y, Y, z, and Z keys to move viewer */   if(key == 'x') viewer[0]-= 1.0;   if(key == 'X') viewer[0]+= 1.0;   if(key == 'y') viewer[1]-= 1.0;   if(key == 'Y') viewer[1]+= 1.0;   if(key == 'z') viewer[2]-= 1.0;   if(key == 'Z') viewer[2]+= 1.0;   display();}void myReshape(int w, int h){ glViewport(0, 0, w, h);/* Use a perspective view */ glMatrixMode(GL_PROJECTION);  glLoadIdentity();	if(w<=h) glFrustum(-2.0, 2.0, -2.0 * (GLfloat) h/ (GLfloat) w,        2.0* (GLfloat) h / (GLfloat) w, 2.0, 20.0);	else glFrustum(-2.0, 2.0, -2.0 * (GLfloat) w/ (GLfloat) h,        2.0* (GLfloat) w / (GLfloat) h, 2.0, 20.0);/* Or we can use gluPerspective */ /* gluPerspective(45.0, w/h, -10.0, 10.0); */ glMatrixMode(GL_MODELVIEW);}voidmain(int argc, char **argv){ glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(500, 500); glutCreateWindow("colorcube"); glutReshapeFunc(myReshape); glutDisplayFunc(display);	glutMouseFunc(mouse);	glutKeyboardFunc(keys);	glEnable(GL_DEPTH_TEST); glutMainLoop();}