# vtk.js: Priority for overlapping surfaces on different actors

**URL:** https://discourse.vtk.org/t/vtk-js-priority-for-overlapping-surfaces-on-different-actors/1757
**Category:** Web
**Created:** [September 13, 2019, 10:54am UTC](https://discourse.vtk.org/t/vtk-js-priority-for-overlapping-surfaces-on-different-actors/1757 "2019-09-13T10:54:29Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![rvilums](https://discourse.vtk.org/user_avatar/discourse.vtk.org/rvilums/32/688_2.png) [@rvilums](https://discourse.vtk.org/u/rvilums)
#### Post date: [September 13, 2019, 10:54am UTC](https://discourse.vtk.org/t/vtk-js-priority-for-overlapping-surfaces-on-different-actors/1757/1 "2019-09-13T10:54:29Z")

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Hello,

Is there a way to tell which surface will be visible, if they overlap?

Imagine, for example, that a green cube is displayed using one actor, and the same cube, but in red, is displayed using another actor. Can I set that red cube has priority? Or are they displayed only in the order they were added to the renderer?

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<div class="post-metadata">

### Author: ![ken-martin](https://discourse.vtk.org/user_avatar/discourse.vtk.org/ken-martin/32/884_2.png) [@ken-martin](https://discourse.vtk.org/u/ken-martin)
#### Post date: [September 13, 2019, 2:37pm UTC](https://discourse.vtk.org/t/vtk-js-priority-for-overlapping-surfaces-on-different-actors/1757/2 "2019-09-13T14:37:46Z")

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You can use topology offset. Something like redCubeMapper.SetRelativeCoincidentTopologyPolygonOffsetParameters(4,4);

Positive values push back, negative pull forward.