gluUnProject issue - Printable Version

Code:
#include <GL/glut.h>

#include <iostream>

#include <stdlib.h>

#include <stdio.h>



void Display();

void Reshape(int w,int h);



static float _angle = 0.0f;

static int stop = 0;

static int rotate  = 0;

static int lastx = 0;

static int lasty = 0;

static float rotation_angle = 0.0f;

static bool edit_poly = false;;

static bool second_point = false;

static       double object_coord_start[3];



void mouseMovement(int x, int y) {

   if(rotate == 1)

   {

     int diffx=x-lastx; //check the difference between the current x and the last x position

     int diffy=y-lasty; //check the difference between the current y and the last y position

     lastx=x; //set lastx to the current x position

     lasty=y; //set lasty to the current y position

     _angle = _angle + (float)diffx;

    glutPostRedisplay(); //Tell GLUT that the display has changed

   }

   else

   {

      lastx = 0;

      lasty = 0;

    }

}



void keyboard (unsigned char key, int x, int y) {

/* Called when a key is pressed */

 if (key == 27) exit (0); /* 27 is the Escape key */

 if(key == 'p')

 {

    edit_poly = true;

 }

}

void mouseEvent(int button, int state, int x, int y)  

{  

   if (button == GLUT_LEFT_BUTTON)  

   {  

    if (state == GLUT_DOWN)  

    {

      rotate = 1;

      lastx = x;

      lasty = y;

      if ( edit_poly == true)

      {

         

         GLint viewport[4];

         GLdouble projection[16],modelview[16];

         GLfloat wx=x,wy,wz;

         glGetIntegerv(GL_VIEWPORT,viewport);

         y=viewport[3]-y;

         wy=y;

         glGetDoublev(GL_MODELVIEW_MATRIX,modelview);

         glGetDoublev(GL_PROJECTION_MATRIX,projection);

         glReadPixels(x,y,1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&wz);

         GLU_FALSE == gluUnProject(wx,wy,wz,modelview,projection,viewport,&object_coord_start[0],&object_coord_start[1],&object_coord_start[2]);

         glutPostRedisplay();

      }



    }

    else if (state == GLUT_UP)  

    {

       rotate = 0;

      if ( edit_poly == true)

      {

          edit_poly = false;

      }

    }



   }

}

int main(int argc,char **argv) {

  glutInit(&argc,argv);

  glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

  glutInitWindowSize(500,500);

  glutInitWindowPosition(100,100);

  glutCreateWindow("ex");

  glEnable(GL_DEPTH_TEST);

  glEnable(GL_COLOR_MATERIAL);

  glutDisplayFunc(Display);

  glutReshapeFunc(Reshape);

  glutKeyboardFunc (keyboard); /* Register the "keyboard" function */

  glutMotionFunc(mouseMovement); //check for mouse movement

  glutMouseFunc(mouseEvent); 

  glutMainLoop();

  return 0;

}



GLdouble ox=0.0,oy=0.0,oz=0.0;

void Display() {

  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

  glLoadIdentity();

  //gluLookAt(10.0,0.0,20.0,0.0,0.0,0.0,0.0,1.0,0.0);

  gluLookAt (0.0, 0.0, 6.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

  glPushMatrix();

  glRotatef(_angle, 0.0f, 1.0f, 0.0f);

  //glRotatef(45,1.0,0.0,0.0);

  glColor3f(1,0,0);

  glBegin(GL_POLYGON);

  glVertex3f(0.0, 0.0, 0.0);

  glVertex3f(2.0, 0.0, 0.0);

  glVertex3f(1.0,2.0,0.0);

  glVertex3f(0.0, 0.0, 0.0);

  //glVertex3f(1.0, 1.0, 2.0);

  glEnd();

  glColor3f(0,1,0);

  glBegin(GL_POLYGON);

  glVertex3f(0.0, 0.0, 0.0);

  glVertex3f(1.0, 2.0, 0.0);

  glVertex3f(1.0,1.0,2.0);

  glVertex3f(0.0, 0.0, 0.0);

  glEnd();

  glColor3f(1,1,0);

  glBegin(GL_POLYGON);

 

  glVertex3f(2.0,0.0, 0.0);

  glVertex3f(1.0,2.0,0.0);

  glVertex3f(1.0, 1.0, 2.0);

 glVertex3f(2.0, 0.0, 0.0);

  glEnd();

  glColor3f(0,0,1);

  glBegin(GL_POLYGON);

  glVertex3f(0.0, 0.0, 0.0);

  glVertex3f(2.0,0.0, 0.0);

  glVertex3f(1.0,1.0,2.0);

  glVertex3f(0.0, 0.0, 0.0);

  glEnd();



  //glPopMatrix();



  glPushMatrix();

  glColor3f(0,1,1);

  glDepthMask(GL_FALSE);

  glTranslated(object_coord_start[0],object_coord_start[1],object_coord_start[2]);

  glutSolidSphere(0.1,15,15);

  glDepthMask(GL_TRUE);

  glPopMatrix();

glutSwapBuffers();



}



void Reshape(int w,int h) {

  glViewport(0,0,w,h);

  glMatrixMode(GL_PROJECTION);

  glLoadIdentity();

  gluPerspective (60, (GLfloat)w / (GLfloat)h, 1.0, 100.0);

  glMatrixMode(GL_MODELVIEW);

}