UGUI研究院之新手引导事件上下分离（二十七）

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
/// <summary>
/// 新手引导动画
/// </summary>
public class Guide : MonoBehaviour {


	public Image target;


	private Vector4 center;
	private Material material;
	private float diameter; // 直径
	private float current =0f;

	Vector3[] corners = new Vector3[4]; 

	void Awake () 
	{

		Canvas canvas = GameObject.Find ("Canvas").GetComponent<Canvas> ();
		target.rectTransform.GetWorldCorners (corners);
		diameter = Vector2.Distance (WordToCanvasPos(canvas,corners [0]), WordToCanvasPos(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);
		material = GetComponent<Image>().material;
		material.SetVector ("_Center", center);
	


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

		material.SetFloat ("_Silder", current);
	}


	float yVelocity = 0f;
	void Update () {


		float value = Mathf.SmoothDamp(current, diameter, ref yVelocity, 0.3f);
		if (!Mathf.Approximately (value, current)) {
			current = value;
			material.SetFloat ("_Silder", current);
		}
	}

	void OnGUI(){
		if(GUILayout.Button("Test")){
			Awake ();
		}
	}


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

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
		}
	}
}