unity-animation

Unity Animation (Animator / Mecanim)

Control animation state with Unity 6.3 LTS's Animator and Animator Controllers: parameters, transitions, blend trees, layers, and humanoid IK. Targets Unity 6.3 LTS (6000.3).

When to use

• Use when connecting animation clips into a state machine, driving them from script via parameters, blending locomotion (idle→walk→run), layering an upper-body action over movement, or adding foot/hand IK on a humanoid rig.
• Use when the project has *.controller (Animator Controller) and *.anim assets, or a rigged model with an Avatar.

When not to use: simple non-skeletal value tweens (UI fades, position lerps) are better done with a tween/coroutine — see unity-csharp-scripting. Timeline cutscenes are a separate tool. 2D sprite frame animation also uses the Animator but with sprite keyframes.

Core workflow

1. Add an Animator to the model and assign an Animator Controller; for a humanoid model, set its rig to Humanoid so it has an Avatar (enables retargeting and IK).
2. Define parameters on the controller — Float (Speed), Bool (IsGrounded), Int, Trigger (Jump) — and states with transitions whose conditions read those parameters.
3. Set parameters from script, never poke states directly: SetFloat, SetBool, SetInteger, SetTrigger. The state machine resolves transitions for you.
4. Blend continuous motion with a Blend Tree (one Float like Speed drives idle↔walk↔run) instead of many discrete states + transitions.
5. Layer additive/override motion (e.g. an upper-body "aim" layer with an Avatar Mask) and control its layerWeight.
6. Verify in the Animator window during Play mode — the live state highlights and parameter values update, so you can see exactly which transition fired (or didn't).

Patterns

1. Drive locomotion + a one-shot action from script

using UnityEngine;

[RequireComponent(typeof(Animator))]
public class CharacterAnim : MonoBehaviour
{
    private Animator _anim;
    // Cache parameter hashes — faster and typo-proof vs string lookups every frame.
    private static readonly int Speed     = Animator.StringToHash("Speed");
    private static readonly int IsGrounded= Animator.StringToHash("IsGrounded");
    private static readonly int Jump      = Animator.StringToHash("Jump");

    private void Awake() => _anim = GetComponent<Animator>();

    public void Tick(float planarSpeed, bool grounded)
    {
        _anim.SetFloat(Speed, planarSpeed);     // drives a 1D blend tree (idle/walk/run)
        _anim.SetBool(IsGrounded, grounded);    // gates a falling/landing transition
    }

    public void DoJump() => _anim.SetTrigger(Jump);  // fire-and-forget; auto-resets after use
}