unity shader logo流光线条

Shader "myPractices/LogoShader"
{
	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
			v2f vert (appdata_base v)
			{
				v2f o;

				o.pos = mul(UNITY_MATRIX_MVP, 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 angleInRed = 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 = (uv.y)/tan(angleInRed);

					//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, i.uv, 0.25, 2, 1, 0.15, 0.5);

				//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
				if(texCol.w >0.5)
				{
					outp = texCol + float4(1,1,1,1) * tmpBrightness;
				}
				else
				{
					outp = float4(0,0,0,0);
				}
				return outp;
			}
			ENDCG
		}
	}
}

工程

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