unity 实现聚合效果

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c#代码部分

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using UnityEngine.EventSystems;
using System.Collections.Generic;

public class T9 : MonoBehaviour
{
    //需要聚合的对象（例子中的Unity图标）
    public Image target;
    //Canvas对象
    public Canvas canvas;

    public RectTransform ta;

    private Vector4 m_Center;
    private Material m_Material;
    private float m_Diameter; //直径
    private float m_Current = 0f;

    Vector3[] corners = new Vector3[4];
    Vector2 tipPos;
    void Awake()
    {

        target.rectTransform.GetWorldCorners(corners);
        m_Diameter = Vector2.Distance(WorldToCanvasPos(canvas, corners[0]),
            WorldToCanvasPos(canvas, corners[2])) / 2f;

        float x = corners[0].x + ((corners[3].x - corners[0].x) / 2f);
        float y = corners[0].y + ((corners[1].y - corners[0].y) / 2f);

        Vector3 center = new Vector3(x, y, 0f);
        Vector2 position = Vector2.zero;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas.transform
            as RectTransform, center, canvas.GetComponent<Camera>(), out position);



     
        center = new Vector4(position.x, position.y, 0f, 0f);
        m_Material = GetComponent<Image>().material;
        m_Material.SetVector("_Center", center);



        (canvas.transform as RectTransform).GetWorldCorners(corners);
        for (int i = 0; i < corners.Length; i++)
        {
            m_Current = Mathf.Max(Vector3.Distance(WorldToCanvasPos(canvas, corners
                [i]), center), m_Current);
        }

        m_Material.SetFloat("_Silder", m_Current);
        tipPos = new Vector2(position.x + 100f, position.y);
    }


    float yVelocity = 0f;
    void Update()
    {
        float value = Mathf.SmoothDamp(m_Current, m_Diameter, ref yVelocity, 0.3f);
        if (!Mathf.Approximately(value, m_Current))
        {
            m_Current = value;
            m_Material.SetFloat("_Silder", m_Current);
            
        }
        else
        {
            ta.anchoredPosition = tipPos;
        }
        if (Input.GetMouseButtonDown(0))
        {
            Awake();
        }
    }



    Vector2 WorldToCanvasPos(Canvas canvas, Vector3 world)
    {
        Vector2 position = Vector2.zero;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas.transform
            as RectTransform, world, canvas.GetComponent<Camera>(), out position);
        return position;
    }

}

Shader部分

Shader "UI/Default_Mask"
{
    Properties
    {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Tint", Color) = (1,1,1,1)

        _StencilComp("Stencil Comparison", Float) = 8
        _Stencil("Stencil ID", Float) = 0
        _StencilOp("Stencil Operation", Float) = 0
        _StencilWriteMask("Stencil Write Mask", Float) = 255
        _StencilReadMask("Stencil Read Mask", Float) = 255

 
        _ColorMask("Color Mask", Float) = 15


        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0

            //-------------------add----------------------
              _Center("Center", vector) = (0, 0, 0, 0)
              _Silder("_Silder", Range(0,1000)) = 1000 //sliders
            //-------------------add----------------------
    }

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

            Stencil
            {
                Ref[_Stencil]
                Comp[_StencilComp]
                Pass[_StencilOp]
                ReadMask[_StencilReadMask]
                WriteMask[_StencilWriteMask]
            }

            Cull Off
            Lighting Off
            ZWrite Off
            ZTest[unity_GUIZTestMode]
            Blend SrcAlpha OneMinusSrcAlpha
            ColorMask[_ColorMask]

            Pass
            {
                Name "Default"
            CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #pragma target 2.0

                #include "UnityCG.cginc"
                #include "UnityUI.cginc"

                #pragma multi_compile __ UNITY_UI_ALPHACLIP

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

                struct v2f
                {
                    float4 vertex : SV_POSITION;
                    fixed4 color : COLOR;
                    float2 texcoord : TEXCOORD0;
                    float4 worldPosition : TEXCOORD1;
                    UNITY_VERTEX_OUTPUT_STEREO

                };

                fixed4 _Color;
                fixed4 _TextureSampleAdd;
                float4 _ClipRect;
                //-------------------add----------------------
                float _Silder;
                float2 _Center;
                //-------------------add----------------------
                v2f vert(appdata_t IN)
                {
                    v2f OUT;
                    UNITY_SETUP_INSTANCE_ID(IN);
                    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                    OUT.worldPosition = IN.vertex;
                    OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

                    OUT.texcoord = IN.texcoord;

                    OUT.color = IN.color * _Color;
                    return OUT;
                }

                sampler2D _MainTex;

                fixed4 frag(v2f IN) : SV_Target
                {
                    half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) *
                        IN.color;

                    color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);

                    #ifdef UNITY_UI_ALPHACLIP
                    clip(color.a - 0.001);
                    #endif
                    //-------------------add----------------------
                       color.a *= (distance(IN.worldPosition.xy,_Center.xy) > _Silder);
                       color.rgb *= color.a;
                       //-------------------add----------------------
                    return color;

                }
            ENDCG
            }
        }
}

 

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