Box2D的碰撞beginContant occurrs不止一次

Question

基於Box2D的文檔和教程在網上查到（最好的一個在這裏http://www.iforce2d.net/b2dtut/collision-anatomy）我認爲碰撞事件處理beginContact應該每次碰撞僅出現一次。

但我的經驗是，在某些情況下（我不能縮小這個下降到什麼特別的事至今）beginContact被調用一次以上。

具體例子：

1st fixture is a box, belongs to static body and is a sensor 

2nd fixture (which is also player body in 2d game I'm building) 
is a polygon, belongs to dynamic body and is not a sensor. 

Both are large enough so in debug mode it is absolutely clear 
when these fixtures start to overlap and when they part. 

Result is - while player body fixture passes through static sensor, 
beginContact is called 3-4 times or more while fixtures keep oveplapping. 
Velocity is moderate (fixtures keep overlapping for a whole second and more). 

我懷念在文檔中的東西嗎？有沒有辦法解決這個問題？

Answer 1

好吧，我想我已經找到了答案，或至少一種解決方法。也許這對別人有幫助。

問題多邊形夾具實際上是一個ChainShape。在這種情況下，對於連鎖店的每個環節來說，聯繫似乎都已經啓動。切換到常規的PolygonShape解決了這個問題。

我認爲這是描述的情況說明書的一部分：

Contacts are objects created by Box2D to manage collision between two fixtures. If the fixture has children, such as a chain shape, then a contact exists for each relevant child. 

Answer 2

是否有在世界上其他附着物，除了剛纔那兩個？您是否在檢查以確保BeginContact事件真的適用於這兩種燈具？有沒有關於這種「3-4倍」的行爲，會讓你懷疑BeginContact可能適用於其他燈具，而不是靜態傳感器？我的猜測是，你的播放器正在從多個燈具組成的地面上移動，並且你看到了播放器和地面燈具之間的BeginContact事件。