【Unity】URP 中的 UGUIShader 实现
参考官方 Shader 代码实现：
https://github.com/TwoTailsGames/Unity-Built-in-Shaders/blob/master/DefaultResourcesExtra/UI/UI-Default.shader
Shader "UI/Template"
{Properties{// PerRendererData 表明纹理由每个渲染器提供，似乎是起某种优化作用。[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// 启用Clip功能，Clip掉的像素将不会参与模板测试等。[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0}SubShader{LOD 100 //内置无光照系列Shader的LOD一般为100Tags{"Queue"="Transparent" // 渲染顺序为透明队列"PreviewType"="Plane" // 材质预览效果为平面"RenderType"="Transparent" // 渲染类型为透明"CanUseSpriteAtlas"="True" // 表明兼容 LegacySpritePacker 图集功能。"IgnoreProjector"="True" // 表明不受内置管线中投影器功能的影响。}//UI利用模板功能实现遮罩效果Stencil{Ref [_Stencil]Comp [_StencilComp]Pass [_StencilOp]ReadMask [_StencilReadMask]WriteMask [_StencilWriteMask]}//渲染器将自动排序，再加上UI都是半透明物体，所以无需深度功能ZWrite OffZTest [unity_GUIZTestMode] // unity_GUIZTestMode 根据当前画布的渲染模式自动设置Blend SrcAlpha OneMinusSrcAlphaColorMask [_ColorMask]Pass{HLSLPROGRAM#pragma vertex VertexPass#pragma fragment PixelPass#pragma shader_feature _ UNITY_UI_ALPHACLIP#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"cbuffer UnityPerMaterial{sampler2D _MainTex;float4 _MainTex_ST;float4 _Color;}struct Vertex{float3 positionOS:POSITION;float4 color : COLOR;float2 uv:TEXCOORD0;};struct Pixel{float4 positionCS:SV_POSITION;float4 color : COLOR;float2 uv:TEXCOORD0;};Pixel VertexPass(const Vertex vertex){Pixel pixel;pixel.positionCS = TransformObjectToHClip(vertex.positionOS);pixel.color = vertex.color * _Color;pixel.uv = TRANSFORM_TEX(vertex.uv, _MainTex);return pixel;}float4 PixelPass(const Pixel pixel):SV_TARGET{float4 color = tex2D(_MainTex, pixel.uv) * pixel.color;#ifdef UNITY_UI_ALPHACLIPclip (pixel.color.a - 0.001);#endifreturn color;}ENDHLSL}}
}