unity-animation

Unity Animation System

Animation System Overview

Unity's Mecanim animation system is built on three interconnected components:

1. Animation Clips -- Unit pieces of motion (Idle, Walk, Run)
2. Animator Controller -- State machine organizing clips into a flowchart of states and transitions
3. Avatar System -- Maps humanoid character skeletons to a common internal format for retargeting

The Animator component is attached to GameObjects and references both the Animator Controller and Avatar assets needed for playback.

Animation Types

• Humanoid -- Requires Avatar configuration; supports retargeting between different character rigs; 15-20% more CPU-intensive than Generic
• Generic -- Animates Transform or MonoBehaviour properties on specific hierarchies; not transferable between different hierarchies
• Legacy -- Older Animation component; use for simple single-shot or UI animations

Animator Controller

An Animator Controller asset arranges Animation Clips and Transitions for a character or animated GameObject.

Creating: Right-click in Project window > Create > Animator Controller

Key Components

• States -- Each state plays an associated Animation Clip or Blend Tree
• Transitions -- Define how and when the state machine switches between states
• Parameters -- Variables (Float, Int, Bool, Trigger) that scripts set to control transitions
• Layers -- Separate state machines for different body parts or animation concerns
• Sub-State Machines -- Nested state machines for hierarchical organization

Parameters

Four types are available:

Type	Description	Script Method
Float	Decimal number	SetFloat() / GetFloat()
Int	Whole number	SetInteger() / GetInteger()
Bool	True/false	SetBool() / GetBool()
Trigger	Auto-resetting bool	SetTrigger() / ResetTrigger()

using UnityEngine;

public class PlayerAnimController : MonoBehaviour
{
    Animator animator;

    void Start()
    {
        animator = GetComponent<Animator>();
    }

    void Update()
    {
        // Note: Uses legacy Input Manager for simplicity. See unity-input for the new Input System.
        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");
        bool fire = Input.GetButtonDown("Fire1");

        animator.SetFloat("Forward", v);
        animator.SetFloat("Strafe", h);
        animator.SetBool("Fire", fire);
    }

    void OnCollisionEnter(Collision col)
    {
        if (col.gameObject.CompareTag("Enemy"))
        {
            animator.SetTrigger("Die");
        }
    }
}