{"id":711,"date":"2022-06-14T22:39:31","date_gmt":"2022-06-14T20:39:31","guid":{"rendered":"https:\/\/www.bellingo.de\/blog\/?p=711"},"modified":"2022-06-14T22:41:40","modified_gmt":"2022-06-14T20:41:40","slug":"devblog-back-to-the-execution-order-pit","status":"publish","type":"post","link":"https:\/\/www.bellingo.de\/blog\/devblog-back-to-the-execution-order-pit\/","title":{"rendered":"DevBlog: Back to the Execution Order Pit"},"content":{"rendered":"\n

My article on script execution order<\/a> in Unity’s UNet networking layer is my most successful article. It is 6 years old now and still being clicked regularly, more often than most others. No small wonder, as I had to find out yet again. Fixing a bug in Network Traders<\/a>, I fell into almost the same trap, again! Always be aware of event execution order<\/em>! And continue reading if you want to know why!<\/p>\n\n\n\n\n\n\n\n

\"Standard<\/a>
The network screen, as it should be.<\/figcaption><\/figure><\/div>\n\n\n\n

So what happened? One of the screens of Network Traders shows a graph with all cities known to the player. In the center, there is the player’s own city, and grouped around it are the cities her merchants have already visited. Since this network can become arbitrarily complex, the screen can be zoomed and scrolled. This worked great during testing with the Unity editor. But when deployed on an Android smartphone, something unexpected happened. The scaling of the central city was totally off, as you can see below.<\/p>\n\n\n\n

Execution Order of Awake and OnEnable<\/h2>\n\n\n\n
\"Bug<\/a>
Broken scaling of objects on the network screen.<\/figcaption><\/figure><\/div>\n\n\n\n

The reason for this unwanted behavior may be a, let’s say, less than optimal class architecture, but very instructive nonetheless. The class which is responsible for zooming the screen, TradeNetworkScaler<\/em>, is a Unity component placed on the same GameObject as the screen manager class itself, TradeNetworkView.<\/em> In Awake<\/em>, the „Scaler“ registers itself with the „View“ object:<\/p>\n\n\n\n

  private void Awake()\n  {\n    tradeNetwork = GetComponent<TradeNetworkView>();\n\n    tradeNetwork.OnNetworkViewEnabling += OnNetworkViewEnable;\n  }<\/code><\/pre>\n\n\n\n
The callback OnNetworkViewEnabling<\/em> is in turn called in OnEnable <\/em>of TradeNetworkView<\/em>. <\/p>\n\n\n\n
So, what’s the problem? The respective Unity documentation on event execution order<\/a> shows it, but I would not have seen it at first glance. Do you?<\/p>\n\n\n\n
\"Screenshot<\/a>
Initial steps of event execution. (Screenshot: Unity Manual<\/a>)<\/figcaption><\/figure>\n\n\n\n
Neither is the description of Awake and OnEnable clear enough to explain what happens. It says:<\/p>\n\n\n\n
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