【006-Shader-阴影】

// 阴影
Shader "Study/06-ShadowShader"
{
    
    
    Properties
    {
    
    
        _MainTex ("Texture", 2D) = "white" {
    
    }
        _HeroTex ("Hero Texture", 2D) = "black" {
    
    }
        _Brightness("Brightness",Range(0,0.6)) = 0.5
    }
    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;

                // 镜像
                o.uv.y = 1-o.uv.y;

                return o;
            }

            sampler2D _MainTex;
            sampler2D _HeroTex;
            float _Brightness;

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                fixed4 col = tex2D(_HeroTex, i.uv);
                
                if(col.a >0)
                {
    
    
                    col.rgb = 0;
                    col.a = _Brightness;
                }
                

                return col;
            }
            ENDCG
        }
    }
}