Opengl , finding distance between two points on run time

after drawing a irregular object using gluPerspective on run time picking file and putting the points in array ,how can i capture a particular point or portion of the object and make necessary changes on run time … main purpose of the assignment is to find distance between two points on portion of the surface i am drawing on run time. whether select and feedback of gl would work?

If you are controlling your objects with variables then you should have no problem.
By using a variable for you object, changing anything about the object at run-time is not a problem.

As for finding distance, just take the two objects xyz locations and find the distance between them.

Originally posted by kamlesh:
after drawing a irregular object using gluPerspective on run time picking file and putting the points in array ,how can i capture a particular point or portion of the object and make necessary changes on run time … main purpose of the assignment is to find distance between two points on portion of the surface i am drawing on run time. whether select and feedback of gl would work?