I’m a beginner making a rough prototype of a sheet-music-themed platformer where the player jumps on musical notes.
I want the interaction between player and musical notes to change based on whether the player is colliding with a musical note sprite for the first time or whether the player has already collided with it at least once before.
The first time, you bounce off the note, it changes color, and it plays a sound. The second and all subsequent times, you fall through the note (or jump up through it) and it still plays a sound as you pass through it, but the sound is quieter, and most importantly, you can’t actually stand on it, run across it, jump, etc.
Here’s the code I’m using now, which does NOT change the collision/2D physics behavior from the first collision to subsequent collisions. (FYI “alreadyBeenHit” is a boolean, and "pitchToPlay, noteVelocity, and noteVelocityDecreaseAfterBeingHit are integers.)
If I add Physics2D.IgnoreCollision in my “else” statement, then “notePlayer.NotePlay” doesn’t actually run.
If I add a second collider to the note sprite and make it a trigger, and use OnTriggerEnter2D, well…things go haywire. The player sprite triggers note sprites that seem too far away and it all just seems sort of glitchy.
I know this is long, but hopefully this info is useful in clarifying what I want and where I am. Thanks so much for any advice you can offer!
I think you are on the correct track to just convert the Collider to a Trigger… but I’m guessing that will only work if you get your player completely OUT of contact with the Collider the first time, otherwise you probably wouldn’t get trigger calls.
Another way might be to have two separate nearly-co-located colliders, one marked as collider, one as trigger, and then disable the collider one after the first hit, but have the trigger one be slightly smaller.
If you do that be sure to use continuous collision check on your player Rigidbody.
To find out what might be going haywire, find out who is hitting who by printing names of GameObjects.
Time to start debugging! Here is how you can begin your exciting new debugging adventures:
You must find a way to get the information you need in order to reason about what the problem is.
Once you understand what the problem is, you may begin to reason about a solution to the problem.
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 names of the GameObjects or Components involved?
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.
You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);
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.
Visit Google for how to see console output from builds. 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 for iOS: How To - Capturing Device Logs on iOS or this answer for Android: How To - Capturing Device Logs on Android
If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.
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.
If your problem is with OnCollision-type functions, print the name of what is passed in!
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:
“When in doubt, print it out!™” - Kurt Dekker (and many others)
Note: the print() function is an alias for Debug.Log() provided by the MonoBehaviour class.
@Kurt-Dekker thanks so much for this treasure trove of info! I will debug this carefully and try the two colliders of slightly different sizes, with one set to a trigger solution that you suggest.
In case anyone’s following this, I took Kurt’s suggestions turned on a GameObject’s collider’s “Is Trigger” checkbox on after the first time the player collides with the object. The issue with the trigger not happening until the player moves a bit away from the object isn’t a problem for my particular use case, so I think I can just roll with it. (Oh, I also added a check for a GameObject tag, because I’m using the script in question for other objects whose colliders shouldn’t be converted into triggers after a collision.)
Here’s my very amateurish, badly-done code now:
private void OnCollisionEnter2D(Collision2D collision)
{
if (alreadyBeenHit == false)
{
// play the note at normal volume
notePlayer.NotePlay(pitchToPlay, noteVelocity);
// mark it as having been hit once
alreadyBeenHit = true;
// if it's a "CollideOnce" tagged object, then make it a trigger only (player can't stand on it, etc. any more) and also change its color
if (collision.otherCollider.CompareTag("CollideOnce"))
{
collision.otherCollider.isTrigger = true;
noteSprite.color = new Color(0.3568628f, 0.3372549f, 0.6980392f, 1f);
}
}
}
private void OnTriggerEnter2D(Collider2D collision)
{
if (alreadyBeenHit == true)
{
notePlayer.NotePlay(pitchToPlay, noteVelocity - noteDecreaseVelocity);
}
}