OpenGL直线拾取

void WALL::pick(GLfloat xpos,GLfloat ypos)
{
xpos,ypos;
GLint viewport[4];
GLdouble mvmatrix[16],projmatrix[16];
float realy;
GLdouble wx,wy,wz;

glGetIntegerv(GL_VIEWPORT,viewport);
glGetDoublev(GL_MODELVIEW_MATRIX,mvmatrix);
glGetDoublev(GL_PROJECTION_MATRIX,projmatrix);

realy =ypos;
printf("%f %f \n",xpos,realy);
gluUnProject((GLdouble)xpos,(GLdouble)realy,0.0,mvmatrix,projmatrix,viewport,&wx,&wy,&wz);
float g_nearxyz[3];
g_nearxyz[0] = (GLfloat)wx;
g_nearxyz[1] = (GLfloat)wy;
g_nearxyz[2] = (GLfloat)wz;////

gluUnProject((GLdouble)xpos,(GLdouble)realy,1.0,mvmatrix,projmatrix,viewport,&wx,&wy,&wz);

float g_farxyz[3];
g_farxyz[0] = (GLfloat)wx;
g_farxyz[1] = (GLfloat)wy;
g_farxyz[2] = (GLfloat)wz;////

float m_fangxiang[3];

for(int i=0 ;i<3 ;i++)
{
m_fangxiang[i] =g_farxyz[i] -g_nearxyz[i];

}
float noml =1/sqrtf(m_fangxiang[0]*m_fangxiang[0]+m_fangxiang[1]*m_fangxiang[1]+m_fangxiang[2]*m_fangxiang[2]);
for(int i=0 ;i<3 ;i++)
{
m_fangxiang[i]*=noml;
}

float distens =-g_nearxyz[1]/m_fangxiang[1];
float onefangxiang[3];
for(int i=0; i<3 ;i++)
{
onefangxiang[i] =distens*m_fangxiang[i]+g_nearxyz[i];

}

for(int i=0 ;i<400 ;i++)
{
pic[i].select =false;
if(abs(onefangxiang[0]-pic[i].x)<4&&abs(onefangxiang[2]-pic[i].y)<4)
{
pic[i].select =true;
}

}
//printf("%f  %f %f \n",onefangxiang[0],onefangxiang[1],onefangxiang[2]);

//printf("line:%f,%f ,%f --->%f ,%f,%f\n",g_nearxyz[0],g_nearxyz[1],g_nearxyz[2],g_farxyz[0],g_farxyz[1],g_farxyz[2]);

}