Weird behaviour with Handles

The following code is inside an Editor script.

Code (CSharp):

1.         Event currentEvent = Event.current;
2.         int controlID = GUIUtility.GetControlID(FocusType.Passive);
3.         EventType mouseEvent = currentEvent.GetTypeForControl(controlID);
4.         if (selectedNode != null && mouseEvent == EventType.MouseDrag)
5.         {
6.             Debug.Log("drag detected");
7.             Handles.DrawLine(selectedNode.UIposition, currentEvent.mousePosition);
8.         }

This code above prints out "drag detected" but doesnt draw the line. But if I move the Handle.DrawLine(... line outside of the if as follows, than it draws the line.

Code (CSharp):

1.         Event currentEvent = Event.current;
2.         int controlID = GUIUtility.GetControlID(FocusType.Passive);
3.         EventType mouseEvent = currentEvent.GetTypeForControl(controlID);
4.         if (selectedNode != null && mouseEvent == EventType.MouseDrag)
5.         {
6.             Debug.Log("drag detected");
7.          
8.         }
9.         Handles.DrawLine(selectedNode.UIposition, currentEvent.mousePosition);
10.  

Any idea what is going on?
Edit: obviously Handle.DrawLine is working, just not inside the if section. The if statement also passes since Debug.Log is also called

 

Debugging editor stuff is just like debugging anything else. After all, "Who debugs the debug code?"

You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

 

I replaced the mouseEvent... with currentEvent and it works like this;

Code (CSharp):

1. if (selectedNode!=null && currentEvent.button==1) //rightmouse button down during selection
2.         {
3.             Handles.DrawLine(selectedNode.UIposition - scroll + incomingEdgeVec, currentEvent.mousePosition);
4.             Repaint();
5.         }