Unity 2d Sprite血条shader

Shader "Custom/SpriteSlicedProgressBar"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
        // 注意：这里的 _ClipX 是具体的本地坐标值，不是 0-1
        _ClipX ("Clip X Position", Float) = 1000.0 
    }

    SubShader
    {
        Tags
        { 
            "Queue"="Transparent" 
            "IgnoreProjector"="True" 
            "RenderType"="Transparent" 
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True" 
        }

        Cull Off
        Lighting Off
        ZWrite Off
        Blend One OneMinusSrcAlpha

        Pass
        {
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile _ PIXELSNAP_ON
            #include "UnityCG.cginc"

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
                float3 localPos : TEXCOORD1; // 新增：传递本地坐标
            };

            fixed4 _Color;
            float _ClipX; // 裁剪阈值

            v2f vert(appdata_t IN)
            {
                v2f OUT;
                OUT.vertex = UnityObjectToClipPos(IN.vertex);
                OUT.texcoord = IN.texcoord;
                OUT.color = IN.color * _Color;
                OUT.localPos = IN.vertex.xyz; // 记录原始模型空间坐标

                #ifdef PIXELSNAP_ON
                OUT.vertex = UnityPixelSnap (OUT.vertex);
                #endif
                return OUT;
            }

            sampler2D _MainTex;

            fixed4 frag(v2f IN) : SV_Target
            {
                // 核心改动：不再比较 UV，而是比较物理坐标
                // 如果当前像素的 X 坐标 > 裁剪阈值，丢弃
                clip(_ClipX - IN.localPos.x);

                fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
                c.rgb *= c.a;
                return c;
            }
        ENDCG
        }
    }
}

using UnityEngine;

namespace GameScripts
{
    public class HealthBar : MonoBehaviour
    {
        [Header( "组件引用" )]
        [SerializeField] private SpriteRenderer frontRenderer;
        [SerializeField] private SpriteRenderer backRenderer;

        [Header( "参数设置" )]
        [Range( 1f, 20f )]
        [SerializeField] private float lerpSpeed = 5f;

        private float _targetFill = 1f;
        private float _bufferFill = 1f;

        private MaterialPropertyBlock _propBlock;
        // 注意：这里属性名变了，对应新 Shader
        private static readonly int ClipXId = Shader.PropertyToID( "_ClipX" );

        private void Awake( )
        {
            _propBlock = new MaterialPropertyBlock( );
            ForceUpdate( 1f );
        }

        private void Update( )
        {
            if ( Mathf.Abs( _bufferFill - _targetFill ) > 0.001f )
            {
                _bufferFill = Mathf.Lerp( _bufferFill, _targetFill, Time.deltaTime * lerpSpeed );
                UpdateOneRenderer( backRenderer, _bufferFill );
            }
        }

        public void Init( float current, float max )
        {
            if ( max <= 0 )
            {
                CLog.LogWarning( $"HealthBar Init: max_{max}" );
                return;
            }
            ForceUpdate( Mathf.Clamp01( current / max ) );
        }

        public void SetHealth( float current, float max )
        {
            if ( max <= 0 ) return;
            float newFill = Mathf.Clamp01( current / max );

            if ( newFill < _targetFill )
            {
                _targetFill = newFill;
                UpdateOneRenderer( frontRenderer, _targetFill );
            }
            else
            {
                ForceUpdate( newFill );
            }
        }

        private void ForceUpdate( float fill )
        {
            _targetFill = fill;
            _bufferFill = fill;
            UpdateOneRenderer( frontRenderer, _targetFill );
            UpdateOneRenderer( backRenderer, _bufferFill );
        }

        // 核心修正逻辑
        private void UpdateOneRenderer( SpriteRenderer rend, float fillPct )
        {
            if ( rend == null ) return;
            if ( _propBlock == null ) _propBlock = new MaterialPropertyBlock( );

            // 1. 获取 Sprite 在本地空间的边界 (包含 Sliced 后的尺寸)
            // localBounds 会自动处理 Pivot 在中心、在左下角等各种情况
            Bounds bounds = rend.localBounds;

            // 2. 计算对应的 X 坐标
            // fillPct = 0 时，x = min.x (左边界)
            // fillPct = 1 时，x = max.x (右边界)
            float clipXValue = Mathf.Lerp( bounds.min.x, bounds.max.x, fillPct );

            // 3. 传给 Shader
            rend.GetPropertyBlock( _propBlock );
            _propBlock.SetFloat( ClipXId, clipXValue );
            rend.SetPropertyBlock( _propBlock );
        }

#if UNITY_EDITOR
        [Header( "Editor Debug" )]
        [Range( 0f, 1f )]
        public float debugFill = 1f;

        private void OnValidate( )
        {
            if ( Application.isPlaying )
            {
                SetHealth( debugFill * 100f, 100f );
            }
            else
            {
                if ( frontRenderer == null ) frontRenderer = GetComponent<SpriteRenderer>( );
                if ( _propBlock == null ) _propBlock = new MaterialPropertyBlock( );
                ForceUpdate( debugFill );
            }
        }
#endif
    }
}