unity shader LOGO闪光效果

Shader "Custom/LOGOFlowLight" {
Properties{
_MainTex("Texture", 2D) = "white" { }
}
SubShader
{
Tags {"Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent"}
Blend SrcAlpha OneMinusSrcAlpha
AlphaTest Greater 0.1
pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"

sampler2D _MainTex;
float4 _MainTex_ST;

struct v2f {
float4  pos : SV_POSITION;
float2  uv : TEXCOORD0;
};

//顶点函数没什么特别的，和常规一样
v2f vert(appdata_base v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
return o;
}

//必须放在使用其的 frag函数之前，否则无法识别。
//核心：计算函数，角度，uv,光带的x长度，间隔，开始时间，偏移，单次循环时间
float inFlash(float angle,float2 uv,float xLength,int interval,int beginTime, float offX, float loopTime)
{
//亮度值
float brightness = 0;

//倾斜角
float angleInRad = 0.0174444 * angle;

//当前时间
float currentTime = _Time.y;

//获取本次光照的起始时间
int currentTimeInt = _Time.y / interval;
currentTimeInt *= interval;

//获取本次光照的流逝时间 = 当前时间 - 起始时间
float currentTimePassed = currentTime - currentTimeInt;
if (currentTimePassed > beginTime)
{
//底部左边界和右边界
float xBottomLeftBound;
float xBottomRightBound;

//此点边界
float xPointLeftBound;
float xPointRightBound;

float x0 = currentTimePassed - beginTime;
x0 /= loopTime;

//设置右边界
xBottomRightBound = x0;

//设置左边界
xBottomLeftBound = x0 - xLength;

//投影至x的长度 = y/ tan(angle)
float xProjL;
xProjL = (uv.y) / tan(angleInRad);

//此点的左边界 = 底部左边界 - 投影至x的长度
xPointLeftBound = xBottomLeftBound - xProjL;
//此点的右边界 = 底部右边界 - 投影至x的长度
xPointRightBound = xBottomRightBound - xProjL;

//边界加上一个偏移
xPointLeftBound += offX;
xPointRightBound += offX;

//如果该点在区域内
if (uv.x > xPointLeftBound && uv.x < xPointRightBound)
{
//得到发光区域的中心点
float midness = (xPointLeftBound + xPointRightBound) / 2;

//趋近中心点的程度，0表示位于边缘，1表示位于中心点
float rate = (xLength - 2 * abs(uv.x - midness)) / (xLength);
brightness = rate;
}
}
brightness = max(brightness,0);

//返回颜色 = 纯白色 * 亮度
float4 col = float4(1,1,1,1) *brightness;
return brightness;
}

float4 frag(v2f i) : COLOR
{
float4 outp;

//根据uv取得纹理颜色，和常规一样
float4 texCol = tex2D(_MainTex,i.uv);

//传进i.uv等参数，得到亮度值
float tmpBrightness;
tmpBrightness = inFlash(75.0f,i.uv,0.25f,5.0f,2.0f,0.15,0.7f);

//图像区域，判定设置为 颜色的A > 0.5,输出为材质颜色+光亮值
//此处的条件判断视具体情况而定
if (texCol.x > 0.1&&texCol.y > 0.1&&texCol.z > 0.1)
//if (texCol.w > 0.5)
outp = texCol + float4(1, 1, 1, 1)*tmpBrightness;
//空白区域，判定设置为 颜色的A <=0.5,输出空白
else
outp = texCol;
//outp = float4(0, 0, 0, 0);

return outp;
}
ENDCG
}
}
}