//游标卡尺
Shader "JC/UI/VernierCaliper"
{
    Properties
    {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Tint", Color) = (1,1,1,1)
 
        _StencilComp("Stencil Comparison", Float) = 8
        _Stencil("Stencil ID", Float) = 0
        _StencilOp("Stencil Operation", Float) = 0
        _StencilWriteMask("Stencil Write Mask", Float) = 255
        _StencilReadMask("Stencil Read Mask", Float) = 255
 
        _ColorMask("Color Mask", Float) = 15
 
        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0

        _rectWidth("Rect Width", Float) = 5
        _rectHeight("Rect Height", Float) = 5
        _LineWidth("Line Width", Float) = 5
        _LineSpace("Line Space", Float) = 10
        _LineHeight("Line Height", Float) = 50
        _LineColor("Line Color", Color) = (0,0,0,1)
    }
 
    SubShader
    {
        Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
            "PreviewType" = "Plane"
            "CanUseSpriteAtlas" = "True"
        }
 
        Stencil
        {
            Ref[_Stencil]
            Comp[_StencilComp]
            Pass[_StencilOp]
            ReadMask[_StencilReadMask]
            WriteMask[_StencilWriteMask]
        }
 
        Cull Off
        Lighting Off
        ZWrite Off
        ZTest[unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask[_ColorMask]
 
        Pass
        {
            CGPROGRAM
#pragma vertex vert
#pragma fragment frag
 
#include "UnityCG.cginc"
#include "UnityUI.cginc"
 
#pragma multi_compile __ UNITY_UI_ALPHACLIP
 
            struct appdata_t
            {
float4 vertex   :
                POSITION;
float4 color    :
                COLOR;
float2 texcoord :
                TEXCOORD0;
            };
 
            struct v2f
            {
float4 vertex   :
                SV_POSITION;
fixed4 color :
                COLOR;
half2 texcoord  :
                TEXCOORD0;
float4 worldPosition :
                TEXCOORD1;
            };
 
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;

            float _rectWidth;
            float _rectHeight;
            float _LineWidth;
            float _LineSpace;
            float _LineHeight;
            fixed4 _LineColor;
 
            v2f vert(appdata_t IN)
            {
                v2f OUT;
                OUT.worldPosition = IN.vertex;
                OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
 
                OUT.texcoord = IN.texcoord;
 
#ifdef UNITY_HALF_TEXEL_OFFSET
                OUT.vertex.xy += (_ScreenParams.zw - 1.0)*float2(-1,1);
#endif
 
                OUT.color = IN.color * _Color;
                return OUT;
            }
 
            sampler2D _MainTex;
 
            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;
 
                color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
 
#ifdef UNITY_UI_ALPHACLIP
                clip(color.a - 0.001);
#endif

                float lw = _LineWidth;
                float lh = _LineHeight;
                float ls = _LineSpace;

                float x = IN.texcoord.x * _rectWidth;
                float y = IN.texcoord.y * _rectHeight;

                float c = x % (lw + ls);
                if (c <= lw) 
                {
                    float v = x / (lw + ls);
                    bool c1 = v % 10 < 1 && y < lh; //10刻度
                    bool c2 = v % 5 < 1 && y < lh * 0.6; //5刻度
                    bool c3 = y < lh * 0.4; //1刻度
                    if (c1 || c2 || c3) color.rgb = _LineColor.rgb; 
                    else color.a = 0;
                }
                else color.a = 0;
 
                return color;
            }
            ENDCG
        }
    }
}