# Molecule builder/ Molecule representation to interact with user.

**URL:** https://discourse.vtk.org/t/molecule-builder-molecule-representation-to-interact-with-user/1988
**Category:** Support
**Created:** [October 27, 2019, 11:10pm UTC](https://discourse.vtk.org/t/molecule-builder-molecule-representation-to-interact-with-user/1988 "2019-10-27T23:10:51Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![pali08](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/p/c77e96/32.png) [@pali08](https://discourse.vtk.org/u/pali08)
#### Post date: [October 27, 2019, 11:10pm UTC](https://discourse.vtk.org/t/molecule-builder-molecule-representation-to-interact-with-user/1988/1 "2019-10-27T23:10:51Z")

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Hello all,

I am working on program in which user can build molecule and measure distances between atom (among other things).

Example use case:

1. User have some hydrocarbon drawn in render window. Clicking H atom will replace clicked H with CH3 (or atom/fragment of his choice)
2. User clicks two atoms and program prints distance between them.

What do you suggest to be the best representation of molecule for this purpose? I think of representing all atoms and bonds as individual actors, but I am not sure if it is way to go.

I know about vtkMolecule and vtkMoleculeMapper, but I am not sure if those would be useful for my purpose (interaction with individual atoms/bonds would be problematic).

Hope I am not asking stupid questions, but I am new to vtk and need some starting point.

Best regards  
pali08.