//	OpenGL problem

#ifdef __APPLE__
#  include <GLUT/glut.h>
#else
#  include <GL/glut.h>
#endif
#include <iostream>

using namespace std;

void passive(int,int);
void reshape(int,int);
void init(void);
void display(void);
void camera(void);
void GetOGLPos(int,int);

int cursorX,cursorY,width,height,centerX=-4,centerY=-3;

GLint viewport[4];
GLdouble modelview[16];
GLdouble projection[16];
GLfloat winX, winY, winZ;
GLdouble posX, posY, posZ;

int main (int argc,char **argv) {
	glutInit (&argc,argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA);
	glutInitWindowSize(1364,689);
	glutInitWindowPosition(0,0);
	glutCreateWindow("Sample");
	init();
	glutDisplayFunc(display);
	glutIdleFunc(display);
		glutPassiveMotionFunc(passive);
	glutReshapeFunc(reshape);
	glutMainLoop();
	return 0;
}

void display() {
	glClearColor (0.0,0.0,0.0,1.0);
	glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	camera();

	glColor3f(1,0,0);
	glPushMatrix();
	glTranslatef(centerX,centerY,0);
	glutSolidSphere(5,50,50);
	glPopMatrix();

	GetOGLPos(cursorX,cursorY);

	glColor3f(1,1,1);
	glBegin(GL_LINES);
	glVertex3f(centerX,centerY,0);
//	glTranslatef(0,0,80);
	glVertex3f(posX,posY,posZ);
//	glTranslatef(0,0,-80);
	glEnd();

cout<<posX<<"  "<<posY<<"  "<<posZ<<"\n";

	glutSwapBuffers();
}

void GetOGLPos(int x, int y)
{
	glGetDoublev( GL_MODELVIEW_MATRIX, modelview );
	glGetDoublev( GL_PROJECTION_MATRIX, projection );
	glGetIntegerv( GL_VIEWPORT, viewport );

	winX = (float)x;
	winY = (float)viewport[3] - (float)y;
	glReadPixels( x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ );

	gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
}

void camera(void) {
	glRotatef(0.0,1.0,0.0,0.0);
	glRotatef(0.0,0.0,1.0,0.0);
	glTranslated(0,0,-20);
}

void init(void) {
	glEnable (GL_DEPTH_TEST);
	glEnable (GL_BLEND);
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_COLOR_MATERIAL);
}

void reshape(int w, int h) {
	width=w; height=h;
	glViewport(0,0,(GLsizei)w,(GLsizei)h); 			//set the viewport to the current window specifications
	glMatrixMode(GL_PROJECTION); 				//set the matrix to projection
	glLoadIdentity();
	gluPerspective(60,(GLfloat)w/(GLfloat)h,1.0,100.0); 	//set the perspective (angle of sight, width, height, , depth)
	glMatrixMode(GL_MODELVIEW); 				//set the matrix back to model
}

void passive(int x1,int y1) {
	cursorX=x1; cursorY=y1;
}