The key to stopping an animation from looping in Unity lies in precisely controlling the Animation Clip’s Wrap Mode and employing scripting to detect the animation’s completion. By understanding these concepts, developers can create more dynamic and responsive gameplay experiences.
Understanding Animation Loop Control
Animations are fundamental to bringing life to your Unity games and applications. However, sometimes the default looping behavior of animations needs to be modified. Understanding how to stop animations from looping and trigger specific actions upon their completion is crucial for creating sophisticated interactions.
The Wrap Mode Property: Your Primary Tool
The Wrap Mode property within an Animation Clip dictates how the animation behaves when it reaches its end. The default setting, often “Loop,” causes the animation to start again from the beginning. To prevent looping, you typically need to change this setting. Common alternatives include:
- Once: The animation plays once and then stops at the final frame. This is often the preferred setting for single-shot animations.
- Clamp Forever: Similar to “Once,” but the animation value remains clamped at the last frame rather than returning to its original value. This can be useful for holding a pose.
- Default: Uses the default wrap mode set in the project’s Quality Settings (usually Loop).
To change the Wrap Mode:
- Select the animation clip in your Project window.
- In the Inspector window, scroll down to the Wrap Mode property.
- Click the dropdown menu and select your desired option (e.g., “Once”).
Scripting for Precision: Detecting Animation End
While changing the Wrap Mode is a good starting point, scripting often provides more granular control. You can use scripts to detect when an animation has finished playing and then trigger specific actions, such as transitioning to another animation, changing game state, or destroying the animated object.
The primary method for achieving this is through the Animation Event system and coroutines.
Using Animation Events:
- Select the animation clip.
- In the Animation window (Window -> Animation -> Animation), open the animation timeline.
- Move the timeline cursor to the end of the animation.
- Click the “Add Event” button (represented by a small marker with a + sign).
- In the Inspector window, you can now assign a function to be called when the animation reaches this point. The function must reside on a script attached to the same GameObject as the Animator component.
Using Coroutines and Animation.isPlaying:
This approach involves checking the Animation.isPlaying property within a coroutine to determine when the animation stops. This is useful for situations where animation events are impractical or when dealing with legacy animation systems.
using UnityEngine;
using System.Collections;
public class AnimationController : MonoBehaviour
{
public Animation anim;
public string animationName;
void Start()
{
anim = GetComponent();
StartCoroutine(PlayAnimationOnce(animationName));
}
IEnumerator PlayAnimationOnce(string animationName)
{
anim.Play(animationName);
yield return new WaitUntil(() => !anim.isPlaying);
Debug.Log("Animation finished!");
// Perform actions after the animation finishes, like transitioning to another animation
}
}
Note: This coroutine method is more relevant for the legacy Animation component. For the newer Animator component, employing animation events or state machine behaviours is often preferred due to their performance and reliability.
State Machine Behaviors: Advanced Control
For more complex scenarios involving Animator Controllers and State Machines, State Machine Behaviors offer a structured way to respond to animation state changes. You can create a custom script that inherits from StateMachineBehaviour and override functions like OnStateEnter, OnStateUpdate, and OnStateExit. OnStateExit is particularly useful for detecting when an animation state has finished playing and transitioning to another state or triggering events.
using UnityEngine;
public class MyStateMachineBehavior : StateMachineBehaviour
{
// This function is called when the state machine finishes evaluating this state
override public void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
{
Debug.Log("Animation State exited!");
// Add your logic here, e.g., transitioning to a new state.
}
}
To use this behavior:
- Create a new C# script (e.g.,
MyStateMachineBehavior). - Paste the code above into the script.
- In your Animator window, select the animation state you want to monitor.
- Click “Add Behaviour” in the Inspector and select your newly created script.
This method is highly recommended for managing animation flow within complex state machines.
Frequently Asked Questions (FAQs)
1. Why isn’t changing the Wrap Mode stopping my animation from looping?
Ensure you’ve selected the Animation Clip itself (e.g., in your Project window), not the GameObject containing the Animator. Also, double-check that the Animator Controller isn’t overriding the Wrap Mode within a State. Sometimes, a transition might be immediately looping back to the same state. Check transition conditions.
2. How can I trigger a different animation after one finishes?
Use Animation Events or State Machine Behaviors. Animation Events allow you to directly call a function when a specific frame is reached. State Machine Behaviors provide a more structured approach for managing transitions between animation states.
3. What’s the difference between “Once” and “Clamp Forever” Wrap Modes?
“Once” plays the animation once and then resets to the initial frame’s values. “Clamp Forever” plays the animation once and then holds the final frame’s values indefinitely. Choose “Clamp Forever” if you need the animated object to maintain its final pose.
4. My animation is part of an Animator Controller. How do I prevent looping in that context?
Within the Animator Controller, select the relevant state. In the Inspector, you’ll find the “Loop Time” checkbox. Uncheck this box to prevent the animation from looping within that specific state. Additionally, ensure that there are appropriate transitions out of the state based on specified conditions.
5. Can I use a script to stop an animation that’s already playing?
Yes. You can use animator.StopPlayback() (where animator is a reference to your Animator component), but this method is often less desirable because it abruptly stops the animation without allowing it to complete its final cycle gracefully. It’s generally better to use animation events or state machine behaviours to trigger a smooth transition or to modify the animator’s parameters based on your game’s logic.
6. I’m using Mecanim. Does the Animation.isPlaying property still work?
No, Animation.isPlaying is primarily for the legacy Animation component. With Mecanim (the newer Animator component), you should instead rely on the Animator.GetCurrentAnimatorStateInfo method to get information about the currently playing animation state, and animation events or State Machine Behaviors for logic tied to animation completion.
7. How do I detect the exact moment an animation finishes playing in code?
Animation Events provide the most precise timing. By adding an event at the very end of the animation, you can guarantee that your function is called at the exact frame the animation concludes.
8. Why isn’t my Animation Event being triggered?
Verify that the function you’re calling from the Animation Event exists on a script attached to the same GameObject as the Animator component. Also, ensure that the function’s signature matches what the Animation Event expects (usually a function with no parameters or a single float parameter). Finally, check for typos in the function name within the Animation Event.
9. How can I prevent looping when importing an animation from an external source?
Many animation import settings can affect looping. In the Inspector window for the imported animation file (e.g., FBX), look for options related to “Loop Time” or “Wrap Mode.” Ensure these are set correctly before using the animation in your scene.
10. Is there a performance difference between using Animation Events and checking Animation.isPlaying in a coroutine?
Animation Events are generally more performant than repeatedly checking Animation.isPlaying in a coroutine, especially within an Update loop. Events are triggered only when needed, whereas a coroutine constantly checks the state. However, Animation.isPlaying and coroutines are often not used with modern Mecanim animation setups. State Machine Behaviors offer a robust, performant alternative for more complex animation interactions within Mecanim.
11. How do I handle animations that should only play once in a sequence, but are part of a blend tree?
In a blend tree, ensure that the parameters controlling the blending are set to values that only trigger the one-time animation when intended. You can achieve this through scripting, setting appropriate conditions in the Animator Controller, and potentially creating separate blend trees or states for different animation sequences.
12. My animation plays partially and then stops. Why?
This might indicate an issue with your animation’s keyframes, especially if you’re using additive animations. Inspect the animation timeline in the Animation window to ensure that keyframes are present throughout the entire duration and that there are no sudden jumps or discontinuities. Also, double-check that there isn’t another animation state or transition interrupting the current animation. Ensure that the animation clip is correctly configured and that there are no conflicts in the animation controller or related scripts.