UGUI流光特效（王者荣耀效果）

这个shader有几个特点：

效果如下：

代码如下：

Shader "UI/Unlit/Flowlight"
{
Properties
{
[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
_Color("Tint", Color) = (1, 1, 1, 1)
[MaterialToggle] PixelSnap("Pixel snap", float) = 0

/* Flowlight */
_FlowlightColor("Flowlight Color", Color) = (1, 0, 0, 1)
_Lengthlitandlar("LangthofLittle and Large", range(0,0.5)) = 0.005
_MoveSpeed("MoveSpeed", float) = 5
_Power("Power", float) = 1
_LargeWidth("LargeWidth", range(0,0.005)) = 0.0035
_LittleWidth("LittleWidth", range(0,0.001)) = 0.002
/* --------- */
_WidthRate("WidthRate",float) = 0
_XOffset("XOffset",float) = 0
_HeightRate("HeightRate",float) = 0
_YOffset("YOffset",float) = 0

/* UI */
_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
/* -- */
}

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

Cull Off
Lighting Off
ZWrite Off
Blend One OneMinusSrcAlpha
ColorMask[_ColorMask]
/* UI */
Stencil
{
Ref[_Stencil]
Comp[_StencilComp]
Pass[_StencilOp]
ReadMask[_StencilReadMask]
WriteMask[_StencilWriteMask]
}
/* -- */
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;
half2 texcoord : TEXCOORD0;
float4 worldPosition: TEXCOORD1;
};

fixed4 _Color;
/* Flowlight */
float _Power;
float _LargeWidth;
float _LittleWidth;
float _Lengthlitandlar;
float _MoveSpeed;
fixed4 _FlowlightColor;
/* --------- */
float _UVPosX;
v2f vert(appdata_t IN)
{
v2f OUT;
OUT.worldPosition = IN.vertex;
OUT.vertex = UnityObjectToClipPos(IN.vertex);
OUT.texcoord = IN.texcoord;
OUT.color = IN.color * _Color;
#ifdef PIXELSNAP_ON
OUT.vertex = UnityPixelSnap(OUT.vertex);
#endif

return OUT;
}

sampler2D _MainTex;
float4 _MainTex_ST;
float _WidthRate;
float _XOffset;
float _HeightRate;
float _YOffset;

bool _UseClipRect;
float4 _ClipRect;
float _ClipSoftX;
float _ClipSoftY;
fixed4 frag(v2f IN) : SV_Target
{
fixed4 c = tex2D(_MainTex, IN.texcoord);
/*使用裁剪*/
if (_UseClipRect)
{
float2 factor = float2(0.0, 0.0);
float2 tempXY = (IN.worldPosition.xy - _ClipRect.xy) / float2(_ClipSoftX, _ClipSoftY)*step(_ClipRect.xy, IN.worldPosition.xy);
factor = max(factor, tempXY);
float2 tempZW = (_ClipRect.zw - IN.worldPosition.xy) / float2(_ClipSoftX, _ClipSoftY)*step(IN.worldPosition.xy, _ClipRect.zw);
factor = min(factor, tempZW);
c.a *= clamp(min(factor.x, factor.y), 0.0, 1.0);
}
/* --------- */

/* Flowlight */
//计算流动的标准uvX从-0.5到1.5范围
_UVPosX = _XOffset +(fmod(_Time.x*_MoveSpeed, 1) * 2 -0.5)* _WidthRate;
//标准uvX倾斜
_UVPosX += (IN.texcoord.y- _HeightRate*0.5- _YOffset)*0.2;
//以下是计算流光在区域内的强度，根据到标准点的距离的来确定强度，为了使变化更柔和非线性，使用距离平方或者sin函数也可以
float lar = pow(1 - _LargeWidth*_WidthRate, 2);
float lit = pow(1 - _LittleWidth*_WidthRate, 2);
//第一道流光，可以累加任意条，如下
fixed4 cadd = _FlowlightColor* saturate((1 - saturate(pow(_UVPosX - IN.texcoord.x,2))) - lar)*_Power /(1-lar);
cadd += _FlowlightColor* saturate((1 - saturate(pow(_UVPosX - _Lengthlitandlar*_WidthRate - IN.texcoord.x, 2))) - lit)*_Power/ (1-lit);

c.rgb += cadd.rgb;
c.rgb *= c.a;
/* --------- */

return c;
}
ENDCG
}
}
}