【004-Shader-闪光特效】

// 闪光特效
/**
01、当两站纹理都不透明进行叠加
02、一个透明，一个不透明，以背景色为主
03、都不透明 就不透明
**/

Shader "Study/04-FlashShader"
{
    
    
    Properties
    {
    
    
        _MainTex ("Texture", 2D) = "white" {
    
    }
        _FlashTex ("Flash Texture", 2D) = "black" {
    
    }
        _Brightness ("Brightness", Range(0,1)) = 0.8 //亮度
        _Offset ("Offset", Range(0,1)) = 0 //偏移量
    }
    SubShader
    {
    
    
        // No culling or depth
        Cull Off ZWrite Off ZTest Always
        Blend SrcAlpha OneMinusSrcAlpha

        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
    
    
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

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

            v2f vert (appdata v)
            {
    
    
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;
            sampler2D _FlashTex;
            float _Offset;
            float _Brightness;

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                fixed4 col_src = tex2D(_MainTex, i.uv);
                fixed4 col_flash = tex2D(_FlashTex,i.uv - fixed2((_Offset* _SinTime.w*0.8),0));

                // float value =(_Brightness* _SinTime.w + 1)/2 ;

                fixed4 col_out = col_src + col_flash*col_src.a * col_flash.a * _Brightness;

                return col_out;
            }
            ENDCG
        }
    }
}