unity LoadingUI处理进度条转圈 渐变效果_unity loading转一圈slider

先上代码

Shader "UI/Loading_Tint"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_Color("Tint", Color) = (1,1,1,1)
		_Progress("进度",Range(0,1)) = 0
		_Lerp("渐变范围",Range(0,1)) = 0
		_Strong("强度",Range(0.01,0.99)) = 0
	}

		SubShader
		{
			Tags
			{
				"Queue" = "Transparent"
				"IgnoreProjector" = "True"
				"RenderType" = "Transparent"
				"PreviewType" = "Plane"
				"CanUseSpriteAtlas" = "True"
			}
	
			Cull Off
			Lighting Off
			ZWrite Off
			ZTest[unity_GUIZTestMode]
			Blend SrcAlpha OneMinusSrcAlpha

			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_CLIP_RECT
				#pragma multi_compile __ UNITY_UI_ALPHACLIP

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

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

				sampler2D _MainTex;
				fixed4 _Color;

				float4 _ClipRect;
				float4 _MainTex_ST;
				float _Progress;
				float _Lerp;
				float _Strong;
				//  1/(2*PI)
				#define halfPI1 0.15915

				v2f vert(appdata_t v)
				{
					v2f o;
					o.worldPosition = v.vertex;
					o.vertex = UnityObjectToClipPos(o.worldPosition);
					o.uv = TRANSFORM_TEX(v.uv, _MainTex);
					o.color = v.color * _Color;
					return o;
				}

				fixed4 frag(v2f i) : SV_Target
				{
					half4 color = (tex2D(_MainTex, i.uv)) * i.color;
					//color.a *= step(i.uv.x, _Progress);
					//计算 进度位子
					float2 uv = i.uv - float2(0.5, 0.5);
					//讲旋转值 归到 0-1之间，此处  以 下为起点。 如果 以左为起点， 调换x ，y位子。 0.5为 半圈
					float radian = (atan2(uv.x, uv.y) *halfPI1 + 0.5);
					//渐变范围处理
					float s1 = step(_Progress - _Lerp, radian);
					//处理渐变值
					float s2 = lerp(0 , 1,  (1/ _Lerp)*(radian- _Progress+ _Lerp))*s1;
					//判定是否需要显示颜色
					color.a *= step(radian, _Progress);
					//叠加渐变
					color.a *= (_Strong +(1- _Strong)* s2);
					
					
					return color;
				}
			ENDCG
			}
		}
}
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