hey guys,

I have a problem in picking. I read the tutorials at lighthouse website and i did exactly what they had taught. Well heres my code :

My renderScene code :

```
GLvoid RenderScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) ;
glLoadIdentity() ;
gluLookAt(CameraObj.mPosition.x , CameraObj.mPosition.y , CameraObj.mPosition.z ,
CameraObj.mView.x , CameraObj.mView.y , CameraObj.mView.z ,
CameraObj.mUp.x , CameraObj.mUp.y , CameraObj.mUp.z) ;
//Draw the x , y , z Axis and the grid initially.
DrawAxis() ;
Draw3DGrid() ;
DrawGrid(GL_RENDER) ;
glScalef(0.030f , 0.030f , 0.030f) ;
glRotatef(180.0 , 0.0f , 1.0f , 0.0f) ;
DrawObject() ;
glFlush() ;
glutSwapBuffers() ;
}
```

Heres my DrawGrid code. This is made of points which I must pick…

```
GLvoid DrawGrid(int mode)
{
if(mode == GL_SELECT)
{
glInitNames();
//glPushName(0);
}
int i , j ;
glDisable(GL_LIGHTING) ;
glPointSize(6.0f) ;
//Draw the line segments
glColor3f(1.0f , 1.0f , 0.0f) ;
for(i = 0 ; i < 8 ; i++)
{
for(j = 0 ; j < 8 ; j++)
{
glBegin(GL_LINE_STRIP) ;
glVertex3f(ControlPoints[i][j][0] , ControlPoints[i][j][1] , ControlPoints[i][j][2]) ;
glVertex3f(ControlPoints[i + 1][j][0] , ControlPoints[i + 1][j][1] , ControlPoints[i + 1][j][2]) ;
glVertex3f(ControlPoints[i + 1][j + 1][0] , ControlPoints[i + 1][j + 1][1] , ControlPoints[i + 1][j + 1][2]) ;
glVertex3f(ControlPoints[i][j + 1][0] , ControlPoints[i][j + 1][1] , ControlPoints[i][j + 1][2]) ;
glVertex3f(ControlPoints[i][j][0] , ControlPoints[i][j][1] , ControlPoints[i][j][2]) ;
glEnd() ;
}
}
//Draw the control vertices.
glColor3f(0.0f , 1.0f , 0.0f) ;
int k = 1 ;
for(i = 0 ; i < 10 ; i++)
{
if(mode == GL_SELECT)
glPushName(i) ;
for(j = 0 ; j < 10 ; j++)
{
if(mode == GL_SELECT)
glPushName(j);
glBegin(GL_POINTS) ;
glVertex3f(ControlPoints[i][j][0] , ControlPoints[i][j][1] , ControlPoints[i][j][2]) ;
glEnd() ;
glPopName() ;
}
glPopName() ;
}
glLineWidth(1.0f) ;
glEnable(GL_LIGHTING) ;
}
```

and heres the code to initialize the selection mode:

```
GLvoid MouseFunc(int Button , int State , int x , int y)
{
int Viewport[4] , Hits ;
if(Button == GLUT_LEFT_BUTTON && State == GLUT_DOWN)
{
glGetIntegerv(GL_VIEWPORT , Viewport) ;
glSelectBuffer(512 , ObjectList) ;
glRenderMode(GL_SELECT) ;
//Enter the projection mode, save the matrix and then load the identity.
glMatrixMode(GL_PROJECTION) ;
glPushMatrix() ;
glLoadIdentity() ;
gluPickMatrix((GLdouble)x , (GLdouble)(Viewport[3] - y) , 4 , 4 , Viewport) ;
glOrtho(-6.0f , 6.0f , -6.0f , 6.0f , -400.0f , 400.0f) ;
glMatrixMode(GL_MODELVIEW) ;
DrawGrid(GL_SELECT) ;
//After drawing , pop back the projection matrix and reset to the modelview matrix.
glMatrixMode(GL_PROJECTION) ;
glPopMatrix() ;
glMatrixMode(GL_MODELVIEW) ;
glFlush() ;
Hits = glRenderMode(GL_RENDER) ;
processHits(Hits , ObjectList) ;
glutPostRedisplay() ;
}
}
```

I cant figure out whats wrong…everytime i click on a vertex i get that the no. of hits is zero.

Plz plz help me out…

Thanx

Yours

Siddharth`