Longest distance between straight line and a curve.

Questions & Answers
1

Hello everyone.

I´ve read a lot of questions that were “similar” to mine but no one has been good for me. The thing is that i want to know the longest distance from a curve and a straight line. The curve line is the touch input of the user, every point, and the straight line is from the start point to the end point.

86725-example.png

What´s the best way to achieve that?

Thank you.

2

I can think of two solutions to this. Since you’re curve is created from touch points of the user, we look for the farthest point to your start-end vector:

  1. For each point, get the vector from start to it. Then use Vector3.project to scale the start-end vector so the connection between it’s tip and the tip of the first vector form a perpendicular vector. the lenght of this vector is what you need to compare when doing this with each point. (See this link for Vector3.project to see what I mean).
  2. When the user has finished his drag, place a transform at the start with it’s up vector pointing towards the end and it’s forward vector into the scene (hopefully the view is 2D :slight_smile: ). Then transform each point into it’s local coordiante system (transform.InverseTransformPoint). The x value of the transformed vector is the distance from the start-end vector to the point transformed.