Opengl mouse pickup question.

See more:

OpenGL

Following is the complete code, the Point3D is a class only with three value:x,y,z represent the coordination.

First thing is draw some points on the screen with the mouse. Then connect them with line. Then I just want to pick up these lines
But it does not work.

Can somebody help me Please? I have struggled for several days. I am exhausted!!!

#include "StdAfx.h"
#include <Windows.h>
#include <gl/GL.h>
#include<gl/glu.h>
#include<gl/glut.h>
#include<time.h>
#include<iostream>  
#include<math.h>
#include<vector>

#include "Point3D.h"

using namespace std;

#define BUFSIZE 512

int screenWidth=340;
int screenHeight=280;


vector<Point3D> P;



static int pickUpModel=0; //1: mouse pickup work  0:close the function of mouse pick up

 void  drawSpere(float x, float y,float z);
 void drawLine2D(GLenum);
  void pickUp(int x, int y);
  void processHits (GLint hits, GLuint buffer[]);
void myInit(void) 

{ 
	glClear (GL_COLOR_BUFFER_BIT);
      glClearColor(1.0, 1.0, 1.0, 0.0);
     glShadeModel(GL_SMOOTH);   
   
  
}
void myDisplay(void)
{
		glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 
   glClearColor(1.0, 1.0, 1.0, 0.0);
   glColor3f (0.0, 1.0, 1.0);
 
}
void myReshape (int w, int h)
{

   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity ();
 //  gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);
   if(w<=h)
		  glOrtho(0,screenWidth*2, 0,  screenHeight*2*(GLfloat)h/w,-screenWidth,screenWidth);
	 else
		   glOrtho(0,screenWidth*2*(GLfloat)w/h,0,screenHeight*2,-screenWidth,screenWidth);
   glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   
}

void myMouse(int button,int state,int x,int y)
{
		
	Point3D X;
    if((state==GLUT_DOWN)&&(button==GLUT_LEFT_BUTTON)&&(pickUpModel==0))
    {

		         X.x=x;
			X.y=screenHeight*2-y; 
			X.z=0;
			P.push_back(X);   
			pointNum++;
			for(int i=0;i<pointNum;i++)
			   drawSpere(P[i].x, P[i].y, P[i].z);
		 
            
		   cout<<x<<"  "<<y<<endl;
	}

	 if((state==GLUT_DOWN)&&(button==GLUT_LEFT_BUTTON)&&(pickUpModel==1))
    {
		pickUp(x,y);
	 }
//	glutSwapBuffers();
	 glFlush();
}

void myMenu(int value){
   if(value==1)
   {
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 
	 
	  P.clear();
	  pointNum=0;
	  idx=0;
	  glFlush();
		
   }
   if(value==2)  
   {
	  drawLine2D(GL_RENDER);

   }
   if(value==3)
   {  
   }
   if(value==4)
	   pickUpModel=1;
   if(value==5)
	   pickUpModel=0;
	 
}
 void  drawSpere(float x, float y,float z)
 {
     glPushMatrix();
		 
   glTranslatef (x, y, 0.0);
   glRotatef (5, 0.0, 1.0, 0.0);
   glutWireSphere(5, 100, 80);    /* draw smaller planet */
   glPopMatrix();
  
 
 }

 void drawLine2D(GLenum mode)
 {
    glLineWidth(5);
	 for(int i=0;i<pointNum;i++){
		 if(mode==GL_SELECT)
		  glPushName(i+1);
		 glBegin(GL_LINE_LOOP);
	           glVertex2f(P[i%pointNum].x, P[i%pointNum].y);
		    glVertex2f(P[(i+1)%pointNum].x, P[(i+1)%pointNum].y);
		 glEnd();
 }
	 	glFlush();
 }

 
 void pickUp(int x, int y)
{
   GLuint selectBuf[BUFSIZE];
   GLint hits;
   GLint viewport[4];


   glGetIntegerv (GL_VIEWPORT, viewport);

   glSelectBuffer (BUFSIZE, selectBuf);
   (void) glRenderMode (GL_SELECT);

   glInitNames();
   glPushName(0);

   glMatrixMode (GL_PROJECTION);
   glPushMatrix ();
   glLoadIdentity ();
/*  create 5x5 pixel picking region near cursor location	*/
   gluPickMatrix ((GLdouble) x, (GLdouble) (viewport[3] - y), 
                  5.0, 5.0, viewport);
   gluOrtho2D (0.0, screenWidth*2.0, 0.0, screenHeight*2.0);


    drawLine2D(GL_SELECT);

   glMatrixMode (GL_PROJECTION);
   glPopMatrix ();
   glFlush ();

   hits = glRenderMode(GL_RENDER);
   processHits (hits, selectBuf);


} 

void processHits (GLint hits, GLuint buffer[])
{
   unsigned int i, j;
   GLuint names, *ptr;

   printf ("hits = %d\n", hits);
   ptr = (GLuint *) buffer;
   for (i = 0; i < hits; i++) {	/*  for each hit  */
      names = *ptr;
      printf (" number of names for hit = %d\n", names); ptr++;
      printf("  z1 is %g;", (float) *ptr/0x7fffffff); ptr++;
      printf(" z2 is %g\n", (float) *ptr/0x7fffffff); ptr++;
      printf ("   the name is ");
      for (j = 0; j < names; j++) {	/*  for each name */
         printf ("%d ", *ptr); ptr++;
      }
      printf ("\n");
   }
}



int main(int argc, char** argv)
{
   glutInit(&argc, argv);
  // glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
   glutInitDisplayMode (GLUT_SINGLE| GLUT_RGB);
   glutInitWindowSize (screenWidth*2, screenHeight*2); 
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   myInit();
   glutDisplayFunc(myDisplay); 
   glutReshapeFunc(myReshape);
    glutMouseFunc(myMouse);
		int id=glutCreateMenu(myMenu);
	glutAddMenuEntry("Clear Screen",1);
	glutAddMenuEntry("InitialDraw",2);
	glutAddMenuEntry("iter",3);
	glutAddMenuEntry("pickUpOpen",4);
	glutAddMenuEntry("pickUpClose",5);
		glutAttachMenu(GLUT_RIGHT_BUTTON); 
   glutMainLoop();
   return 0;
}

What I have tried:

I just copy the OpenGL redbook(7th) chapter 13 code and modify to choose line,but it just doesn't work!