# How to find segments intersection?

Hi !

Is there any way to find an intersection between two segments ? Or rays ?
I searched the Ray doc and I found that there is methods for finding an intersecting vector with triangles, boxes, and spheres, so I am surprised to find none with segments.

Hi!
Could you explain it more detailed? What segments? Segments of what?

As â€śsegmentsâ€ť I mean arrays of two vector3.

the intersecting vetor3 between [ [0,5,0], [0,-5,0] ] and [ [5,0,0], [-5,0,0 ] ] would be [0,0,0].

AFAIK, there is no such functionality â€śout-of-the-boxâ€ť in Three.js.

Are points of those two lines (segments) always co-planar? Do those lines (segments) always intersect?

Thanks anyway,

But it is surprising, as Ray.intersectBox() can find an intersecting vector between a ray and a three-dimensional object, Iâ€™d expected that the functionality was available as well for an (a priori) simpler task (intersection between two rays). I will try to find a workaround and keep you posted.

For my use, the lines can be not-coplanar, and it should be possible to return null if there is no intersection.

Just out of curiousily, why do you want to use finding intesection between lines? Whatâ€™s the task?

I want to make a function to offset polylines (array of vector3) according to their bisectors.
In order to code a parametric geometry. (so the user can change the shape of the polyline, and the offset will adapt).

Could you provide an explanatory picture?

In blue the base polyline, in black the polyline offset from the blue according to bisectors.

Maybe this topic will be useful for you:

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Thank you, I will use that as a starting point !