I cannot pickup anything~Please help me with the mouse pickup problem

OpenGL OpenGL: Basic Coding
1

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 doesn’t work.

Can somebody help me Please? I’ve 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,screenWidth2, 0, screenHeight2*(GLfloat)h/w,-screenWidth,screenWidth);
else
glOrtho(0,screenWidth2(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&lt;pointNum;i++)
		   drawSpere(P[i].x, P[i].y, P[i].z);
	 
        
	   cout&lt;&lt;x&lt;&lt;"  "&lt;&lt;y&lt;&lt;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, screenWidth2.0, 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
“, hits);
ptr = (GLuint ) buffer;
for (i = 0; i < hits; i++) { / for each hit */
names = *ptr;
printf (” number of names for hit = %d
“, names); ptr++;
printf(” z1 is %g;”, (float) *ptr/0x7fffffff); ptr++;
printf(" z2 is %g
“, (float) ptr/0x7fffffff); ptr++;
printf (" the name is ");
for (j = 0; j < names; j++) { / for each name */
printf (”%d “, *ptr); ptr++;
}
printf (”
");
}
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);
// glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
glutInitDisplayMode (GLUT_SINGLE| GLUT_RGB);
glutInitWindowSize (screenWidth2, screenHeight2);
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;
}