Unity中用C#脚本修改Animator变量及解决动画触发异常问题

Hey there! Let's fix your animation issues step by step and get that Idle/Walk/Run cycle working exactly how you want it.

First, Diagnose the Core Problem #

Looking at your Update code, two key issues are causing the unwanted walking animation:

1. You’re setting the Animator’s Speed parameter to your fixed speed variable before checking input — so even when you’re not pressing WASD, you’re feeding a non-zero value to the Animator.
2. You’re passing the fixed movement speed instead of the actual current movement magnitude based on player input — the Animator’s Speed parameter should reflect whether the player is moving, not just your default movement speed.

Fix the Code & Implement Idle/Walk/Run #

Here’s a revised script with explanations:

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    [Header("Movement Settings")]
    public float walkSpeed = 3f;
    public float runSpeed = 6f;

    private Animator animator;
    private float currentSpeed;

    void Start()
    {
        // Grab the Animator component attached to your player
        animator = GetComponent<Animator>();
        // Start with walk speed by default
        currentSpeed = walkSpeed;
    }

    void Update()
    {
        // 1. Get player input first
        float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");
        
        // 2. Toggle run with Shift
        if (Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.RightShift))
        {
            currentSpeed = runSpeed;
        }
        else
        {
            currentSpeed = walkSpeed;
        }

        // 3. Calculate movement direction and move the player
        Vector3 moveDirection = new Vector3(horizontal, 0f, vertical).normalized;
        transform.Translate(moveDirection * currentSpeed * Time.deltaTime);

        // 4. Set the Animator's Speed parameter based on actual movement
        float animatorSpeed = moveDirection.magnitude * currentSpeed;
        animator.SetFloat("Speed", animatorSpeed);
    }
}

Key Changes Explained:

• Input first, then Animator update: We now check input before updating the Animator, so we only send a non-zero value when the player is actually moving.
• moveDirection.normalized: Ensures consistent movement speed regardless of diagonal input.
• animatorSpeed calculation: Combines input magnitude (0 when idle, 1 when moving) with current walk/run speed — this gives the Animator a clear value to trigger the right animation.
• Shift run toggle: Switches between walk and run speed seamlessly.

Set Up Your Animator Controller Correctly #

Make sure your transitions match these conditions to avoid jitter:

• Idle → Walk: Transition condition: Speed > 0.1 (use a small threshold instead of 0 to ignore tiny input noise)
• Walk → Idle: Transition condition: Speed <= 0.1
• Walk → Run: Transition condition: Speed >= runSpeed - 0.5 (adjust the threshold to match your runSpeed value)
• Run → Walk: Transition condition: Speed < runSpeed - 0.5
• Enable Has Exit Time for smooth animation blending, or disable it for instant state switches (adjust based on your game’s feel).

How to Modify Animator Variables with C# Scripts #

Here are the most common methods to control Animator parameters, with examples:

• Float parameters: Use animator.SetFloat("ParameterName", value); (like we did with Speed). For better performance, precompute a hash:

  private int speedHash = Animator.StringToHash("Speed");
  // Then use:
  animator.SetFloat(speedHash, animatorSpeed);
  

• Bool parameters: Use animator.SetBool("IsRunning", true/false); — perfect for toggle states like "is jumping" or "is crouching".
• Integer parameters: Use animator.SetInteger("WeaponType", 2); — useful for switching between multiple states (e.g., different weapons).
• Trigger parameters: Use animator.SetTrigger("Attack"); — triggers a one-time animation (resets automatically after the transition).

Troubleshooting Your Previous Attempts #

• Checking "Parameter" on animation clips: That’s for adding animation curves that modify parameters during an animation, not for controlling transitions between animations — so that wasn’t the right fix here.
• Using Mathf.Abs(speed): This only makes the speed positive, but since you were passing the fixed speed variable instead of input-based movement, it didn’t solve the idle issue.

内容的提问来源于stack exchange，提问作者Philip Ch.