#include <GL/glut.h>
#include <math.h>
#include <stdio.h>

// Rotating cube - ideas borrowed from Hisashi Shirokawa

GLuint WIN_WIDTH=glutGet(GLUT_SCREEN_WIDTH)/2.0;
GLuint WIN_HEIGHT=glutGet(GLUT_SCREEN_HEIGHT)/2.0;

GLfloat d2r = 0.0174532;
GLfloat hAngle = 45.0, vAngle = 45.0;

GLfloat eyex=0, eyey=0, eyez=0;

 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 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, int color)
{
 glBegin(GL_POLYGON);
 glColor3fv(colors[color]);
 glVertex3fv(vertices[a]);
 glColor3fv(colors[color]);
 glVertex3fv(vertices[b]);
 glColor3fv(colors[color]);
 glVertex3fv(vertices[c]);
 glColor3fv(colors[color]);
 glVertex3fv(vertices[d]);
 glEnd();
}

void cube()
{
	polygon(0,1,5,4,7); // bottom blue green
	polygon(0,3,2,1,0);	// back black
	polygon(0,4,7,3,3); // left green
	polygon(2,3,7,6,2); // top yellow
	polygon(1,2,6,5,4); // right blue
	polygon(4,5,6,7,1); // front red
}

// Point on sphere at origin (0,0,0) of radius r given hAngle=horizontial and vAngle=vertical angle
void eyeAt(GLfloat r)				
{	eyez = r * sin(vAngle*d2r) * cos(hAngle*d2r);
	eyex = r * sin(vAngle*d2r) * sin(hAngle*d2r);
	eyey = r * cos(vAngle*d2r);
}

void display() {
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 eyeAt(7.0);

 glMatrixMode(GL_MODELVIEW);
 glLoadIdentity();

 printf("(%f,%f,%f) %f %f\n",eyex,eyey,eyez,hAngle,vAngle);

 gluLookAt(eyex,eyey,eyez,0,0,0,0,1,0);
 cube();
 glutSwapBuffers();
 glFlush();
}

void reshape(int w, int h) {
	glViewport(0,0,w,h);
	WIN_WIDTH=w;
	WIN_HEIGHT=h;
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.0,(GLfloat)(WIN_WIDTH)/(GLfloat)(WIN_HEIGHT),0.1,70.0);
    glMatrixMode(GL_MODELVIEW); 
}
void move(int x, int y)
{
	hAngle = (360.0/WIN_WIDTH)*((double)x+1);		// Allow 360 degree
	vAngle = (180.0/WIN_HEIGHT)*((double)y+1);		// Allow 180 degree
	glutPostRedisplay();
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH ); 
	glutInitWindowSize(WIN_WIDTH,WIN_HEIGHT);
    glutCreateWindow("View cube");
    glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	glutPassiveMotionFunc(move);

    glMatrixMode(GL_MODELVIEW);
	glEnable(GL_DEPTH_TEST);
    glClearColor (1.0, 1.0, 1.0, 0.0);

	glutMainLoop();
}