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By Design

Votes

0

Found in

2019.4

2020.3

2021.1

2021.1.14f1

2021.2

2022.1

Issue ID

1349563

Regression

No

Reversing sprite shape makes CompositeCollider2D cutout it's PolygonCollider2D's shape within a bounding BoxCollider2D

Physics2D

-

How to reproduce:
1. Open the user attached project (DevSpriteshape.zip)
2. In the SampleScene select the "Closed Sprite Shape" GameObject from the Hierarchy
3. Observe the CompositeCollider2D's lines in the scene view

Expected result: There are no collider lines except for the BoxCollider2D's
Actual result: There is a hole cut out indicated by the collider lines within the bounding BoxCollider2D

Reproducible with: 2019.4.29f1, 2020.3.14f1, 2021.1.16f1, 2021.2.0b5, 2022.1.0a3

Notes:
1. Reproducible on Ubuntu 18.04 and Windows 10
2. The sprite shape can be reversed by dragging its most bottom left point past the other two to the top right
3. The CompositeCollider2D should never use one Collider2D to cut out another. It should only merge them

  1. Resolution Note:

    So this is caused by the output winding of SpriteShape being determined by the winding order the sprite shape is drawn. Both the PolygonCollider2D and the CompositeCollider2D use opposing windings to define fill or holes. It is not correct to say that the CompositeCollider2D should only merge. If you place a CW path in the PolygonCollider2D and use in the CompositeCollider2D then it will produce a hole (by design).

    The problem here is that the docs for SpriteShape need an additional note about windings and their effect on the output path for 2D colliders.

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