title: CircleCollider2D is not registering collisions with some tiles in a TileMapCollider2D
body: <p>(I've asked this question over at Unity Answers too, but it can sometimes take a while to get a response there, if I get an answer there I'll put it here too.)</p>
  
  <p>I'm making a tile based game that uses Grid > Tilemap with cell layout as Hexagon.</p>
  
  <p>The player can move a certain distance based on movement level. My plan is to highlight valid movement spaces in green and invalid in red. To do this I've got a child GameObject called MovementRange that has a CircleCollider2D attached with it's radius matching the player's movement level. All settings as default.</p>
  
  <p>The TileMap uses a TileMapCollider2D. As each tile on the grid is smaller than the actual grid hexagon this means that each tile is separated by a gap. The TileMapCollider2D correctly assigns each tile a hexagonal collider. All settings as default. The tilemap also has a Rigidbody2D set as Kinematic and Use Full Kinematic Contacts checked.</p>
  
  <p>This is the function used to highlight the tiles in range:</p>
  
  <pre><code>void HighlightCellsInRange(Collision2D collision)
   {
       Vector3 hitPosition = Vector3.zero;
       ContactPoint2D[] contacts = new ContactPoint2D[100];
       int contactCount = collision.GetContacts(contacts);
  
       for (int i = 0; i &lt; contactCount; i++)
       {
           Vector3Int tile = _tileMap.WorldToCell(contacts[i].point);
           _tileMap.SetTile(tile, _greenTile);
           _tilesInRange.Add(tile);
       }
   }
  </code></pre>
  
  <p>This works correctly for any tile that a collision is registered for. The problem is that some tiles don't register collisions (and others have multiple collisions).</p>
  
  <p>Here are some screen shots where you can see what's happening:</p>
  
  <p>I have generated gizmo spheres at all of the collision contacts returned. The circle collider is selected so you can see that clearly there are missing tile collision contact points. There's 6 missing in the very center of the circle collider!</p>
  
  <p><a href="https://i.stack.imgur.com/jliMT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jliMT.png" alt="CircleCollider2D missing contacts"></a></p>
  
  <p>In this screen shot you can see the grid and that every tile is displaying active hexagonal colliders.</p>
  
  <p><a href="https://i.stack.imgur.com/PbYen.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PbYen.png" alt="TilemapCollider2D tiles colliders"></a></p>
  
  <p>I've tried changing the settings on the circle collider and the tilemap collider but I can't understand why some of the collisions are not registering.</p>
  
  <p>Any advice would be appreciated. Thanks</p>