# Idenity segments in Linesegment2 raycast

**URL:** <https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606>\
**Category:** Questions\
**Tags:** raycaster, lines\
**Created:** [November 10, 2020, 3:58pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606 "2020-11-10T15:58:15Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![sumitkumar25](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/sumitkumar25/32/14521_2.png) [@sumitkumar25](https://discourse.threejs.org/u/sumitkumar25)\
**Post date:** [November 10, 2020, 3:58pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/1 "2020-11-10T15:58:15Z")

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Hello,  
I am able to raycast to lineSegment2. How to identify which segment is raycasted as segment has numerous points.

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**Author:** ![gkjohnson](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/gkjohnson/32/2298_2.png) [@gkjohnson](https://discourse.threejs.org/u/gkjohnson)\
**Post date:** [November 10, 2020, 4:47pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/2 "2020-11-10T16:47:05Z")

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You should be able to use `faceIndex` to get that:

> <https://github.com/mrdoob/three.js/blob/f4b504f004867f1ab7fa1645a10fd991d6db158e/examples/jsm/lines/LineSegments2.js#L193>

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**Author:** ![sumitkumar25](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/sumitkumar25/32/14521_2.png) [@sumitkumar25](https://discourse.threejs.org/u/sumitkumar25)\
**Post date:** [November 10, 2020, 5:36pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/3 "2020-11-10T17:36:54Z")

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Thanks.  
I was able to utilize faceIndex for my usecase.  
However in my use case e.g.  
positions = [node0,node1,node0,node2,node0,node3];  
faceIndex values are coming out as a multiple of 2. Is that expected behaivour?

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**Author:** ![gkjohnson](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/gkjohnson/32/2298_2.png) [@gkjohnson](https://discourse.threejs.org/u/gkjohnson)\
**Post date:** [November 10, 2020, 5:59pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/4 "2020-11-10T17:59:54Z")

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Looking at the code that doesn’t sound right – can you make a [jsfiddle](https://jsfiddle.net/ruc3h17j/) to show what’s happening?

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**Author:** ![sumitkumar25](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/sumitkumar25/32/14521_2.png) [@sumitkumar25](https://discourse.threejs.org/u/sumitkumar25)\
**Post date:** [November 10, 2020, 7:47pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/5 "2020-11-10T19:47:18Z")

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@gkjohnson

> **[Edit fiddle - JSFiddle - Code Playground](https://jsfiddle.net/87o25ukw/43/)**

Please have a look.  
FaceIndices are console listed.

Thanks.

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**Author:** ![gkjohnson](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/gkjohnson/32/2298_2.png) [@gkjohnson](https://discourse.threejs.org/u/gkjohnson)\
**Post date:** [November 10, 2020, 8:31pm UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/6 "2020-11-10T20:31:28Z")

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You have to use LineSegmentsGeometry rather than LineGeometry otherwise it will create lines connecting every point.

> **[Edit fiddle - JSFiddle - Code Playground](https://jsfiddle.net/5uyhkjz7/)**

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<div class="post-metadata">

**Author:** ![sumitkumar25](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.threejs.org/sumitkumar25/32/14521_2.png) [@sumitkumar25](https://discourse.threejs.org/u/sumitkumar25)\
**Post date:** [November 11, 2020, 4:13am UTC](https://discourse.threejs.org/t/idenity-segments-in-linesegment2-raycast/20606/7 "2020-11-11T04:13:14Z")

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@gkjohnson Thank You. It works .