6.片断的舍弃Clip

Shaderlab片断剪切/裁剪定义：

Shader "WSP/FrameWork7"
{
    Properties
    {
        _Tex("角色贴图",2D) = "White" {}
        _Color("被击中颜色",Color) = (0,0,0,0)
        _Dissolve("溶解遮罩",2D) = "White" {}
        _Clip("裁剪数值",Range(0,1)) = 0
    }
    SubShader
    {
        pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            sampler2D _Tex;
            fixed4 _Color;
            sampler2D _Dissolve;
            fixed _Clip;
            struct appdata
            {
                float4 vertex :POSITION;
                float4 uv :TEXCOORD;
            };
            struct v2f
            {
                float4 pos :POSITION;
                float4 uv :TEXCOORD;
            };
            v2f vert(appdata v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }
            fixed4 frag(v2f i):SV_TARGET
            {
                fixed4 c;
                fixed4 tex = tex2D(_Tex,i.uv);
                c = tex;
                c += _Color;
                fixed4 dissolveTex = tex2D(_Dissolve,i.uv);
                clip(dissolveTex-_Clip);
                return c;
            }
            ENDCG
        }
    }
}

因为Clip=（x）, x<0时会进行裁剪剔除 那么通过 Clip = （遮罩贴图 - _Clip) 进行判断。通过控制_Clip的数值来决定最终遮罩裁剪值是否＜0；
(x)
所以先定义Clip的值；

_Clip(“裁剪数值”,Range(0,1)) = 0

把值限定在一个合适的范围内并默认为0

然后定义一张溶解遮罩贴图；

_Dissolve(“溶解遮罩”,2D) = “White” {}

在CGPROGRAM进行声明

sampler2D _Dissolve;
fixed _Clip;

然后再片断着色器中进行纹理采样；

fixed4 dissolveTex = tex2D(_Dissolve,i.uv);

最终进行Clip值判断运算

Clip = (dissolveTex - _Clip);