# Timer and Mouse call back connection

**URL:** https://discourse.vtk.org/t/timer-and-mouse-call-back-connection/2188
**Category:** Support
**Created:** [December 1, 2019, 5:16pm UTC](https://discourse.vtk.org/t/timer-and-mouse-call-back-connection/2188 "2019-12-01T17:16:59Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![banikr](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/b/b9bd4f/32.png) [@banikr](https://discourse.vtk.org/u/banikr)
#### Post date: [December 1, 2019, 5:16pm UTC](https://discourse.vtk.org/t/timer-and-mouse-call-back-connection/2188/1 "2019-12-01T17:16:59Z")

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What I am trying to do is very simple in concept, but I don’t know how to do it in VTK as a beginner.  
I have picked up a point in a 3D image using Mousecallback. The point I am calling seed point gives me world coordinates and point ID.  
Now I want to use that seed point and find the nearest point and draw a line between two…the new point is now seed point and have to iterate this in the next timer callback.

I can share the codes I have written if necessary.