大地图高性能路径引导 Shader

控制脚本

using UnityEngine;

[ExecuteAlways]
[RequireComponent( typeof( MeshFilter ), typeof( MeshRenderer ) )]
public class QuadTilingLine : MonoBehaviour
{
    [Header( "Settings" )]
    public Vector3 targetPosition; // 目标点
    public float lineWidth = 0.5f;

    // 内部缓存
    private Transform _t;
    private Renderer _ren;
    private MaterialPropertyBlock _block;
    private MeshFilter _mf;
    private static readonly int LengthId = Shader.PropertyToID( "_TotalLength" );

    private void Awake( )
    {
        Init( );
        // 核心：生成一个轴心在左边的Mesh，彻底解决位置偏移问题
        GenerateLeftPivotMesh( );
    }

    private void Init( )
    {
        if ( _t == null ) _t = transform;
        if ( _ren == null ) _ren = GetComponent<Renderer>( );
        if ( _mf == null ) _mf = GetComponent<MeshFilter>( );
        if ( _block == null ) _block = new MaterialPropertyBlock( );
    }

    private void OnValidate( )
    {
        Init( );
        // 编辑器下如果Mesh丢了，重新生成
        if ( _mf.sharedMesh == null || _mf.sharedMesh.name != "LeftPivotQuad" )
        {
            GenerateLeftPivotMesh( );
        }
        UpdateTransform( );
    }

    // 【代码接口】只传目标坐标
    public void SetTarget( Vector3 targetPos )
    {
        targetPosition = targetPos;
        UpdateTransform( );
    }

    // 真正的逻辑：只转、只缩、不移位
    private void UpdateTransform( )
    {
        if ( _ren == null ) return;

        // 1. 计算向量 (相对于父节点/当前节点的位置)
        // 既然是子物体，起点就是我当前的位置 (_t.position)
        Vector3 dir = targetPosition - _t.position;
        float dist = dir.magnitude;

        if ( dist < 0.001f )
        {
            _ren.enabled = false;
            return;
        }
        _ren.enabled = true;

        // 2. 旋转：Z轴指向目标
        float angle = Mathf.Atan2( dir.y, dir.x ) * Mathf.Rad2Deg;
        _t.rotation = Quaternion.Euler( 0, 0, angle );

        // 3. 缩放：X轴变长 (因为Mesh轴心在左边，所以它只向右长，不用修位置！)
        _t.localScale = new Vector3( dist, lineWidth, 1f );

        // 4. Shader Tiling 修正
        _ren.GetPropertyBlock( _block );
        _block.SetFloat( LengthId, dist );
        _ren.SetPropertyBlock( _block );
    }

    // 【一劳永逸】生成左轴心 Mesh
    private void GenerateLeftPivotMesh( )
    {
        Mesh mesh = new Mesh( );
        mesh.name = "LeftPivotQuad";

        // 顶点：X从 0 到 1 (关键！原点在左边)，Y从 -0.5 到 0.5 (居中)
        Vector3[] vertices = new Vector3[]
        {
            new Vector3(0, -0.5f, 0),
            new Vector3(1, -0.5f, 0),
            new Vector3(0, 0.5f, 0),
            new Vector3(1, 0.5f, 0)
        };

        // UV
        Vector2[] uv = new Vector2[]
        {
            new Vector2(0, 0),
            new Vector2(1, 0),
            new Vector2(0, 1),
            new Vector2(1, 1)
        };

        // 三角形索引
        int[] triangles = new int[] { 0, 2, 1, 2, 3, 1 };

        mesh.vertices = vertices;
        mesh.uv = uv;
        mesh.triangles = triangles;
        mesh.RecalculateBounds( );

        _mf.mesh = mesh;
    }
}

Shader

Shader "Unlit/QuadTilingLine"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", Color) = (1,1,1,1)
        _Density ("Density", Float) = 1.0 
        _ScrollSpeed ("Scroll Speed", Float) = -1.0
    }
    SubShader
    {
        Tags { "Queue"="Transparent" "RenderType"="Transparent" }
        Blend SrcAlpha OneMinusSrcAlpha
        ZWrite Off
        Cull Off // 双面渲染，防止旋转消失

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

            struct appdata { float4 vertex : POSITION; float2 uv : TEXCOORD0; };
            struct v2f { float2 uv : TEXCOORD0; float4 vertex : SV_POSITION; };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _Color;
            float _Density;
            float _TotalLength; // 由脚本传入
            float _ScrollSpeed;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                float2 uv = TRANSFORM_TEX(v.uv, _MainTex);

                uv.x *= _TotalLength * _Density;
                uv.x += _Time.y * _ScrollSpeed;

                o.uv = uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                return tex2D(_MainTex, i.uv) * _Color;
            }
            ENDCG
        }
    }
}