简介

使用shader创建材质球，赋值到UGUI的对象上，使该UGUI对象始终渲染在最上层。
原文章中是在制作VR项目时，但其实在除Screen Space-Overlay状态下，都可使用。只要符合实际需求即可。
因为拥有该shader的UGUI不会被一般的3D物体所遮挡，故要根据具体需求使用。

shader

shader出自：https://blog.csdn.net/u013032852/article/details/77642262

Shader "UI/Overlay"
{Properties{[PerRendererData] _MainTex("Font 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}SubShader{LOD 100Tags{"Queue" = "Transparent""IgnoreProjector" = "True""RenderType" = "Transparent""PreviewType" = "Plane""CanUseSpriteAtlas" = "True"}Stencil{Ref[_Stencil]Comp[_StencilComp]Pass[_StencilOp]ReadMask[_StencilReadMask]WriteMask[_StencilWriteMask]}Cull OffLighting OffZWrite OffZTest AlwaysOffset -1, -1Blend SrcAlpha OneMinusSrcAlphaColorMask[_ColorMask]Pass{CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#include "UnityUI.cginc"struct appdata_t{float4 vertex : POSITION;float2 texcoord : TEXCOORD0;float4 color : COLOR;};struct v2f{float4 vertex : SV_POSITION;half2 texcoord : TEXCOORD0;fixed4 color : COLOR;};sampler2D _MainTex;float4 _MainTex_ST;fixed4 _Color;fixed4 _TextureSampleAdd;v2f vert(appdata_t v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);o.color = v.color * _Color;
#ifdef UNITY_HALF_TEXEL_OFFSETo.vertex.xy += (_ScreenParams.zw - 1.0)*float2(-1,1);
#endifreturn o;}fixed4 frag(v2f i) : SV_Target{fixed4 col = (tex2D(_MainTex, i.texcoord) + _TextureSampleAdd) * i.color;clip(col.a - 0.01);return col;}ENDCG}}
}