distance between a ray and a point

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How do I calculate the distance between a ray and a point ?

Answer 1

Best Answer

Answer by mcdroid · May 05, 2011 at 01:43 AM

DaveA, it's too complicated here is the solution

 public static float DistanceToLine(Ray ray, Vector3 point)
 {
     return Vector3.Cross(ray.direction, point - ray.origin).magnitude;
 }

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UltimateBrent · Nov 20, 2011 at 08:59 AM 15

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For those curious the actual point of intersection on the ray is: ray.origin + ray.direction * Vector3.Dot(ray.direction, point - ray.origin)

ThomLaurent UltimateBrent · Nov 24, 2021 at 04:49 PM 0

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An alternative using Projection to get intersection point: ray.origin + Vector3.Project(point - ray.origin, ray.direction)

julkiewicz · Sep 09, 2016 at 11:55 PM 4

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For those wondering where this came from, it's the same principle as here:

https://www.youtube.com/watch?v=tYUtWYGUqgw

just in 3d. Also I understand this exploits the fact that ray.direction is always normalized (therefore no need dividing by magnitude of direction, which is = 1 always).

craig4android · Jun 23, 2019 at 10:36 PM 0

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ty you are a lifesaver

Answer 2

Answer by friuns3 · Aug 25, 2013 at 09:11 PM

   public static float DistancePointLine(Vector3 point, Vector3 lineStart, Vector3 lineEnd)
     {
         return Vector3.Magnitude(ProjectPointLine(point, lineStart, lineEnd) - point);
     }
     public static Vector3 ProjectPointLine(Vector3 point, Vector3 lineStart, Vector3 lineEnd)
     {
         Vector3 rhs = point - lineStart;
         Vector3 vector2 = lineEnd - lineStart;
         float magnitude = vector2.magnitude;
         Vector3 lhs = vector2;
         if (magnitude > 1E-06f)
         {
             lhs = (Vector3)(lhs / magnitude);
         }
         float num2 = Mathf.Clamp(Vector3.Dot(lhs, rhs), 0f, magnitude);
         return (lineStart + ((Vector3)(lhs * num2)));
     }

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Diablo_sv21 · Jun 14, 2014 at 02:17 AM 0

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This is exactly what I needed! Thank you!

JokerDen · May 05, 2021 at 06:21 PM 0

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Thanks! You saved a lot of time. Don't have idea that 1E-06f means :D

elenzil JokerDen · May 05, 2021 at 06:24 PM 1

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1E-06f is scientific-notation shorthand for 0.1 so 0.000001, a tiny number.

Answer 3

Answer by OR_Parga · Oct 03, 2016 at 08:45 PM

HandleUtility.DistancePointLine

https://docs.unity3d.com/ScriptReference/HandleUtility.DistancePointLine.html

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MattLebrao · Apr 28, 2018 at 07:00 AM 0

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Simplest answer ever! Hahahaha Thanks a lot! :D

Bunny83 MattLebrao · Apr 28, 2018 at 07:49 AM 2

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This is an editor only solution since the HandleUtility is an editor class which can not be used at runtime (which means you can not use it in your game, only in editor scripts).

MattLebrao Bunny83 · Apr 28, 2018 at 09:45 AM 0

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That's good to know, but for my current problem (which is in an editor script) that will do it :)

JokerDen · May 05, 2021 at 06:40 PM 0

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Sad it working only at Editor and not in Runtime (you can't build the project with usage of UnityEditor class).

Answer 4

Answer by elenzil · Oct 03, 2016 at 10:26 PM

if your point and line are two-dimensional, i have an extremely efficient routine for calculating the distance between them, documented here.

in general for questions like this, it's hard to beat Paul Bourke.

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Answer 5

Answer by DaveA · May 05, 2011 at 12:19 AM

http://www.codeguru.com/forum/printthread.php?t=194400

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TheMightySeaSlug · Feb 23, 2018 at 03:23 PM 0

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https://www.thefreedictionary.com/overcomplicate

distance between a ray and a point

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