OpenGL

//	OpenGL problem

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

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

int cursorX,cursorY,width,height;
double centerX,centerY,centerZ;
//GLfloat modelviewMatrix[16],projectionMatrix[16];
GLdouble modelviewMatrix[16],projectionMatrix[16];
GLint viewport[4];

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);

	//	Render 3D content
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60,(GLfloat)width/(GLfloat)height,1.0,100.0); 	// create 3D perspective projection matrix
	glMatrixMode(GL_MODELVIEW);
	glPushMatrix();
	camera();
	glTranslatef(-6,-2,0);
	glColor3f(1,0,0);
	glutSolidSphere(5,50,50);
	glPopMatrix();

	glGetDoublev(GL_MODELVIEW_MATRIX, modelviewMatrix);
	glGetDoublev(GL_PROJECTION_MATRIX, projectionMatrix);
	glGetIntegerv(GL_VIEWPORT, viewport);
	// get 3D coordinates based on window coordinates
	gluProject(-6, -2, 0, modelviewMatrix, projectionMatrix, viewport, &centerX, &centerY, &centerZ);

	// Render 2D content
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0, width,height, 0); 				// create 2D orthographic projection matrix
	glMatrixMode(GL_MODELVIEW);
	glColor3f(1,1,1);
	glBegin(GL_LINES);
		glVertex2f( centerX,centerY );			// coordinate of center of the sphere in orthographic projection
		glVertex2f( cursorX,cursorY );
	glEnd();

	glutSwapBuffers();
}

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;
}

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