7.UV的Tiling与Offset

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;float4 _Dissolve_ST;
            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.xy = v.uv.xy;
                //o.uv.zw = v.uv *_Dissolve_ST.xy+_Dissolve_ST.zw;
                o.uv.zw = TRANSFORM_TEX(v.uv,_Dissolve);
                return o;
            }
            fixed4 frag(v2f i):SV_TARGET
            {
                fixed4 c;
                fixed4 tex = tex2D(_Tex,i.uv.xy);
                c = tex;
                c += _Color;
                fixed4 dissolveTex = tex2D(_Dissolve,i.uv.zw);
                clip(dissolveTex-_Clip);
                return c;
            }
            ENDCG
        }
    }
}*

Tiling x y
Offset x y

sampler2D _Dissolve; float4 _Dissolve_ST;

_ST红色标注后，我们就可以在代码中去使用和控制Tiling和Offset；

Tiling: 瓷砖式显示，并列式窗口;也就是贴图的重复度；xy分别代表他u、v的重复次数；
Offset：偏移；xy分别代表u、v的偏移数值；

UV本身是二维向量，所以通过声明 float4 _Dissolve_ST 来代表Tiling和Offset
其中xy代表TIling的xy，zw代表offset的xy
在贴图采样时使用以下方法：
TRANSFORM_TEX(uv,_Name) = v.uv *_Dissolve_ST.xy+_Dissolve_ST.zw;

用来实现贴图UV的Tiling与Offset在暴露属性面板上的实时控制

xr=1 , r=1 xr=2x , r=2