Question Transforming local polygon points to Word Position

EDIT: I read this as PolygonCollider2D, forgive me if this isn't the case. Nevertheless, I'll leave this info here as it might help someone.


Here's an example of how to do it:

Code (CSharp):

1. using System.Collections.Generic;
2. using UnityEngine;
3.  
4. public class PolygonOutline : MonoBehaviour
5. {
6.    public PolygonCollider2D PolygonCollider;
7.  
8.    private readonly List<Vector2> m_Path = new();
9.  
10.    private void OnDrawGizmos()
11.    {
12.        if (!PolygonCollider)
13.          return;
14.  
15.       // Fetch the polygon path.
16.       var vertexCount = PolygonCollider.GetPath(0, m_Path);
17.  
18.       // Fetch the polygon path and transform it to world-space.
19.       var colliderTransform = PolygonCollider.transform.localToWorldMatrix;
20.       for (var i = 0; i < vertexCount; ++i)
21.          m_Path[i] = colliderTransform.MultiplyPoint(m_Path[i]);
22.  
23.       // Draw the path.
24.       Gizmos.color = Color.yellow;
25.       for (var i = 0; i < vertexCount; ++i)
26.       {
27.          var j = (i + 1) % vertexCount;
28.          Gizmos.DrawLine(m_Path[i], m_Path[j]);
29.       }
30.    }
31. }

As a note: the path isn't an actual physics shape so instead you can get the actual physics shape(s) that the polygon (or any collider) produces with Collider2D.GetShapes along with the local-to-world matrix to transform those shapes with Rigidbody2D.localToWorld (and Collider2D.localToWorld) but you cannot use these Matrix4x4 for the path. They also don't contain any scaling as that is already baked into the physics shape(s).

Finally, you can also create a representation as a planar mesh if you desire with Collider2D.CreateMesh and Collider2D.GetShapeHash to detect if the shapes have changed.

Hope that helps.

 

I believe that landed in 2019.3.

Bounds are not useful at all in this case as they're an AABB i.e. a non-rotated encapsulating box.

It's pretty trivial, something like this:

Code (CSharp):

1. using UnityEngine;
2.  
3. public class DrawBoxGizmo : MonoBehaviour
4. {
5.     public BoxCollider2D Box;
6.     public Color GizmoColor = Color.white;
7.  
8.     private readonly Vector3[] m_Vertices = new Vector3[4];
9.  
10.     private void OnDrawGizmos()
11.     {
12.         if (!Box)
13.             return;
14.  
15.         // Fetch the box details.
16.         var boxTransform = Box.transform;
17.         var boxSize = Box.size;
18.         var extents = new Vector3(boxSize.x * 0.5f, boxSize.y * 0.5f, 0f);
19.         var offset = (Vector3)Box.offset;
20.  
21.         // Calculate the box vertices.
22.         m_Vertices[0] = offset - extents;
23.         m_Vertices[1] = offset + new Vector3(-extents.x, extents.y);
24.         m_Vertices[2] = offset + extents;
25.         m_Vertices[3] = offset + new Vector3(extents.x, -extents.y);
26.  
27.         // Transform the box.
28.         boxTransform.TransformPoints(m_Vertices);
29.  
30.         // Draw the vertices.
31.         Gizmos.color = GizmoColor;
32.         var vertexCount = m_Vertices.Length;
33.         for (var s = 0; s < vertexCount; ++s)
34.         {
35.             var t = (s + 1) % vertexCount;
36.             Gizmos.DrawLine(m_Vertices[s], m_Vertices[t]);
37.         }
38.     }
39. }
40.  

 

Note: TransformPoints came in 2022 with Span<T> support so in earlier versions, just iterate the points using TransformPoint but obviously it's not critical to the answer which is contained in lines 22-28.

 

Is there a reason you keep asking about different specific colliders? Polygon then Box now Circle. The result is the same really, I don't follow the specific question you're asking. It's just the Transform stuff above.

 

But to answer your question; you can grab the single shape it creates (CircleShape) and read that radius (using the GetShapes API above) or if you want to just calculate it without reading the shape, you can do:

Code (CSharp):

1. using UnityEngine;
2.  
3. public class DrawCircleScript : MonoBehaviour
4. {
5.     public CircleCollider2D Circle;
6.     public Color GizmoColor = Color.white;
7.  
8.     private void OnDrawGizmos()
9.     {
10.         if (Circle == null)
11.             return;
12.  
13.         var circleTransform = Circle.transform;
14.  
15.         // Fetch the transform scale.
16.         var scale = circleTransform.lossyScale;
17.        
18.         // Scale the circle radius by the maximum of the XY scale.
19.         // NOTE: Ellipse is not supported so this is used.
20.         var scaledRadius = Circle.radius * Mathf.Max(scale.x, scale.y);
21.  
22.         // Draw it.
23.         Gizmos.color = GizmoColor;
24.         Gizmos.DrawSphere(circleTransform.position + (Vector3)Circle.offset, scaledRadius);
25.     }
26. }
27.  

 

At least respond to my post above; did it help?

Whilst I'm happy to help, endless questions without responses isn't something I'm here for TBH.

 

Try looking at the links above I've mentioned twice now. It gives you the actual shapes it produces.

 

You do, you're not reading the posts above:

https://forum.unity.com/threads/tra...points-to-word-position.1487883/#post-9275364

Simplt look at the version drop down in the scripting docs and select your Unity version and you'll see it's there.

https://docs.unity3d.com/2021.2/Documentation/ScriptReference/Collider2D.CreateMesh.html
https://docs.unity3d.com/2021.2/Documentation/ScriptReference/Collider2D.GetShapes.html

 

Nobody has said you need to change your Unity Version.

You're doing something wrong then if you cannot see it so you need to fix that on your side; not ask for equivalent functionality for what's already there.

Unity 2021.3.30f1 although I get the same in 2019.3:


2019.3 source reference:
https://github.com/Unity-Technologi...indings/Physics2D.bindings.cs#L3291C1-L3291C1

 

I'm sorry but it's impossible to not have that method if you're using 2019.3 onwards. Methods don't just disappear. Something else is going on here.

You seem to be arguing against things like TransformPoint saying that it doesn't work but it works perfectly in the example I took the time to write for you here and that handles offset correctly so did you try it?

https://www.nuget.org/packages/LibTessDotNet
https://github.com/AngusJohnson/Clipper2


I believe I've provided enough information for all your questions here now so good luck.