ShaderLab 偏移不渲染一个多边形在另一个之上

Question

我有两个着色器，UnlitRGBA 和 TransparentNoOverlap。他们如下：

UnlitRGBA.shaderlab

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
// modified by rbjacob101

Shader "Particles/Standard Unlit (RGBA)"
{
    Properties
    {
        _MainTex("Albedo", 2D) = "white" {}
    _Color("Color", Color) = (1,1,1,1)

        _Cutoff("Alpha Cutoff", Range(0.0, 1.0)) = 0.5

        _BumpScale("Scale", Float) = 1.0
        _BumpMap("Normal Map", 2D) = "bump" {}

    _EmissionColor("Color", Color) = (0,0,0)
        _EmissionMap("Emission", 2D) = "white" {}

    _DistortionStrength("Strength", Float) = 1.0
        _DistortionBlend("Blend", Range(0.0, 1.0)) = 0.5

        _SoftParticlesNearFadeDistance("Soft Particles Near Fade", Float) = 0.0
        _SoftParticlesFarFadeDistance("Soft Particles Far Fade", Float) = 1.0
        _CameraNearFadeDistance("Camera Near Fade", Float) = 1.0
        _CameraFarFadeDistance("Camera Far Fade", Float) = 2.0

        // Hidden properties
        [HideInInspector] _Mode("__mode", Float) = 0.0
        [HideInInspector] _ColorMode("__colormode", Float) = 0.0
        [HideInInspector] _FlipbookMode("__flipbookmode", Float) = 0.0
        [HideInInspector] _LightingEnabled("__lightingenabled", Float) = 0.0
        [HideInInspector] _DistortionEnabled("__distortionenabled", Float) = 0.0
        [HideInInspector] _EmissionEnabled("__emissionenabled", Float) = 0.0
        [HideInInspector] _BlendOp("__blendop", Float) = 0.0
        [HideInInspector] _SrcBlend("__src", Float) = 1.0
        [HideInInspector] _DstBlend("__dst", Float) = 0.0
        [HideInInspector] _ZWrite("__zw", Float) = 1.0
        [HideInInspector] _Cull("__cull", Float) = 2.0
        [HideInInspector] _SoftParticlesEnabled("__softparticlesenabled", Float) = 0.0
        [HideInInspector] _CameraFadingEnabled("__camerafadingenabled", Float) = 0.0
        [HideInInspector] _SoftParticleFadeParams("__softparticlefadeparams", Vector) = (0,0,0,0)
        [HideInInspector] _CameraFadeParams("__camerafadeparams", Vector) = (0,0,0,0)
        [HideInInspector] _ColorAddSubDiff("__coloraddsubdiff", Vector) = (0,0,0,0)
        [HideInInspector] _DistortionStrengthScaled("__distortionstrengthscaled", Float) = 0.0
    }

        Category
    {
        SubShader
    {
        Tags{ "RenderType" = "Opaque" "IgnoreProjector" = "True" "PreviewType" = "Plane" "PerformanceChecks" = "False" }

        BlendOp[_BlendOp]
        Blend[_SrcBlend][_DstBlend]
        ZWrite[_ZWrite]
        Offset -1, -1
        Cull[_Cull]
        ColorMask RGBA

        GrabPass
    {
        Tags{ "LightMode" = "Always" }
        "_GrabTexture"
    }

        Pass
    {
        Name "ShadowCaster"
        Tags{ "LightMode" = "ShadowCaster" }

        BlendOp Add
        Blend One Zero
        ZWrite On
        Cull Off

        CGPROGRAM
#pragma target 2.5

#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON _ALPHAMODULATE_ON
#pragma shader_feature _ _COLOROVERLAY_ON _COLORCOLOR_ON _COLORADDSUBDIFF_ON
#pragma shader_feature _REQUIRE_UV2
#pragma multi_compile_shadowcaster
#pragma multi_compile_instancing
#pragma instancing_options procedural:vertInstancingSetup

#pragma vertex vertParticleShadowCaster
#pragma fragment fragParticleShadowCaster

#include "UnityStandardParticleShadow.cginc"
        ENDCG
    }

        Pass
    {
        Tags{ "LightMode" = "ForwardBase" }

        CGPROGRAM
#pragma multi_compile __ SOFTPARTICLES_ON
#pragma multi_compile_fog
#pragma target 2.5

#pragma shader_feature _ _ALPHATEST_ON _ALPHABLEND_ON _ALPHAPREMULTIPLY_ON _ALPHAMODULATE_ON
#pragma shader_feature _ _COLOROVERLAY_ON _COLORCOLOR_ON _COLORADDSUBDIFF_ON
#pragma shader_feature _NORMALMAP
#pragma shader_feature _EMISSION
#pragma shader_feature _FADING_ON
#pragma shader_feature _REQUIRE_UV2
#pragma shader_feature EFFECT_BUMP

#pragma vertex vertParticleUnlit
#pragma fragment fragParticleUnlit
#pragma multi_compile_instancing
#pragma instancing_options procedural:vertInstancingSetup

#include "UnityStandardParticles.cginc"
        ENDCG
    }
    }
    }

        Fallback "VertexLit"
        CustomEditor "StandardParticlesShaderGUI"
}

TransparentNoOverlap.shader

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

/*
 * Taken from:
 * https://forum.unity.com/threads/transparent-depth-shader-good-for-ghosts.149511/
 */

Shader "Transparent/TransparentNoOverlap" {
Properties {
     [PerRendererData]_Color ("Main Color", Color) = (1,1,1,1)
    _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
}

SubShader {
    Tags {"RenderType"="Transparent" "Queue"="Transparent" "IgnoreProjector"="True"}
    LOD 200

    Pass {
        Name "TRANSPARENT"

        ZWrite On
        ZTest LEqual
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask RGBA

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #include "UnityCG.cginc"

        fixed4 _Color;

        struct v2f {
            float4 pos : SV_POSITION;
        };

        v2f vert (appdata_base v)
        {
            v2f o;
            o.pos = UnityObjectToClipPos (v.vertex);
            return o;
        }

        half4 frag (v2f i) : COLOR
        {
            return _Color;
        }
        ENDCG  
    }

    CGPROGRAM
    #pragma surface surf Lambert alpha
    #pragma debug

    sampler2D _MainTex;
    fixed4 _Color;

    struct Input {
        float2 uv_MainTex;
    };

    void surf (Input IN, inout SurfaceOutput o) {
        fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
        o.Albedo = c.rgba;
        o.Alpha = c.a;
    }
    ENDCG
}

Fallback "Transparent/Diffuse"
}

我希望使用 UnlitRGBA 的材质始终在 TransparentNoOverlap 上渲染。为了达到这个结果我会怎么做？我尝试将 Offset -1, -1 或 Offset 0, -1 添加到 UnlitRGBA。当针对标准表面着色器对此进行测试时，它工作正常并且 UnlitRGBA 始终呈现在顶部。但是当使用 TransparentNoOverlap 渲染时，要么存在 z-fighting，要么 TransparentNoOverlap 总是渲染在顶部。为什么是这样？我想这可能与 ZTests 或 ZWrites 有关，但我最终不确定。

对于大量代码示例，我深表歉意...感谢您提供的任何帮助。

rbjacob

Answer 1

请注意，预期结果和设置略有歧义，因此可能有多种方法。

简单地说：Material 着色器 A（无光照）被 B（透明）覆盖，因为 B 是在它之后绘制的。 "Queue"="Transparent" 是在 B 中负责该效果的标志。着色器 A 没有它，所以它使用默认的 "Geometry" 队列。（你可以在这里阅读引擎盖下使用的索引值：https://docs.unity3d.com/Manual/SL-SubShaderTags.html）。因此，在这方面，您可以明确指定队列索引，并确保它们符合您的预期行为。

这忽略了另一个方面：处理一个网格被另一个网格遮挡的 ZBuffer，使得它们实际上不依赖于该绘制顺序。可以根据深度测试丢弃像素，如果指定，深度可以按对象写入。 (https://docs.unity3d.com/Manual/SL-CullAndDepth.html)

网格显示 z-fighting 如果它们都写入和测试，并且是 co-planar（在同一位置）或缓冲区精度低，因此存储的值看起来像是。

假设你的mesh既要遮挡又要遮挡别人和自己，一种方法是设置B（Transparent）使用ZTest Less，这样它只出现当 A 根本不存在时，即使在 A 之后绘制，即使 co-planar with A.

ShaderLab 偏移不渲染一个多边形在另一个之上

ShaderLab offset not rendering one polygon above the other

unity3d

shader

shaderlab