[Still unsolved] Is there some way to cast lines and get the point where they intersect?

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So I need the distance between two points.

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However, this is harder when the objects are rotated, since the point I need to get is no longer the x and y coordinates of the others (1, 6).

alt text

Hope someone answers. Writing in paint was really hard...

Answer 1

Answer by IvovdMarel · Oct 10, 2018 at 11:59 PM

I recommend using transform.InverseTransformPoint to calculate the local position of the collision. You should only have to look at the x or z value then (as the origin would be 0,0,0)

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Feref2 · Oct 11, 2018 at 02:25 AM 0

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Sorry, but how? I tried this and the collisions weren´t were they were supposed to:

 void OnCollisionStay2D (Collision2D coll)
 {
     for ( int l = 0; l < coll.contacts.Length; l++)
     {
         if (this.transform.position.x > coll.contacts[l].point.x)
         {
             leftPos = this.transform.InverseTransformPoint (coll.contacts[l].point);       
         }
     }
  
     for (int r = 0; r < coll.contacts.Length; r++)
     {
         if (this.transform.position.x < coll.contacts[r].point.x)
         {   
             rightPos = this.transform.InverseTransformPoint(coll.contacts[r].point);
         }
     } 
 
     diff = $$anonymous$$athf.Abs(rightPos.x - leftPos.x);
 
 }

IvovdMarel Feref2 · Oct 11, 2018 at 02:39 AM 0

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 void OnCollisionStay2D (Collision2D coll)
  {
      
      for ( int l = 0; l < coll.contacts.Length; l++)
      {
          Vector3 globalPos = coll.contacts[l].point;
          Vector3 localPos = this.transform.InverseTransformPoint(globalPos);
          if (localPos.x < leftPos.x)
          {
              leftPos = localPos;       
          } else if (localPos.x > rightPos.x)
          {    
             rightPos = localPos;
          }
      }
 
      diff = $$anonymous$$athf.Abs(rightPos.x - leftPos.x);
  
  }

IvovdMarel IvovdMarel · Oct 11, 2018 at 02:40 AM 0

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This should get the most left position and the most right position and calculate the difference. I didn't test it though so there might be some problems.

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Answer 2

Answer by Bunny83 · Oct 11, 2018 at 08:30 AM

The distance between two "points" of course requires you to use all coordinates. Just looking at the x value (no matter if it's local or world space) of course doesn't work in every case.

From your code it's not clear what you actually need. There could be more than 2 collision points and it's not clear which ones you actually want. If you want to find the two points which are the farthest apart it becomes a bit more complicated. You would need to check each collision point against every other to find the greatest distance.

Basically something like that:

 int count = coll.contacts.Length;
 Vector3 point0;
 Vector3 point1;
 float distSqr = 0;
 for ( int i = 0; i < count - 1; i++)
 {
     Vector3 p0 = coll.contacts[i].point;
     for (int n = i+1; n < count; n++)
     {
         Vector3 p1 = coll.contacts[i].point;
         float d = (p0-p1).sqrMagnitude;
         if (d > distSqr)
         {
             point0 = p0;
             point1 = p1;
             distSqr = d;
         }
     }
 }
 float distance = Mathf.Sqrt(distSqr);

Here "point0" and "point1" will contain the two points which are farthest apart from each other and "distance" will contain the distance between those two points. You get the same by using:

float distance = Vector3.Distance(point0, point1);
at the end

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Feref2 · Oct 11, 2018 at 05:46 PM 0

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Well, thanks, but I actually need to do this: https://gamedev.stackexchange.com/questions/113149/how-can-i-squeeze-a-game-object-when-it-is-pressed-between-two-others/113290 I made some changes to that code, but as you can see, that doesn´t work if the obects are rotated. Getting the distance between the furthest points doesn´t work either. If the squeezers are not perfectly aligned, the distance between those collisions will be bigger than the actual object´s width. That´s why I wanted only the x distance. When the objects aren´t rotated is just x - x and ignoring y and z axis.

[Still unsolved] Is there some way to cast lines and get the point where they intersect?

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