gluUnProject function

GLint gluUnProject(GLdouble     winX,
				   GLdouble     winY,
				   GLdouble     winZ,
				   const GLdouble * model,
				   const GLdouble * proj,
				   GLdouble *  objX,
				   GLdouble *  objY,
				   GLdouble *  objZ);

• winX, winY, winZ
  Specify the window coordinates to be mapped
  
  
• model
  Specify the modelview matrix(as from a glGetDoublev call)
  
  
• proj
  Specify the projection matrix(as from a glGetDoublev call)
  
  
• objX, objY, objZ
  Returns the computed object coordinates.