UPR Lit Shader解析（2）—前向渲染Pass

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UPR Lit Shader解析（2）—前向渲染Pass

//  Forward pass. Shades all light in a single pass. GI + emission + FogPass//前向渲染的Pass，所有光照效果都在该Pass中计算，包括全局光照、自发光和雾效{// Lightmode matches the ShaderPassName set in UniversalRenderPipeline.cs. SRPDefaultUnlit and passes with// no LightMode tag are also rendered by Universal Render PipelineName "ForwardLit"//Pass的名字，给Pass命名，方便复用Tags{"LightMode" = "UniversalForward"}//光照模式标签一定要与UniversalRenderPipeline.cs中对应，如果先写Unlit shader，可以不用该标签Blend[_SrcBlend][_DstBlend]//混合操作，参数的值来自于 Properties块中的定义ZWrite[_ZWrite]Cull[_Cull]HLSLPROGRAM //Shader代码块不像内置渲染管线一样使用CGPROGRAM--ENDCG包裹，而使用HLSLPROGRAM--ENDHLSL包裹//CG表示 C for Graphic,HLSL表示High Level Shader Language//使用HLSL中引用任何内容都需要显式添加，而CG会隐式添加，会添加进不需要的东西，导致文件变大#pragma only_renderers gles gles3 glcore d3d11 //图形API预编译指令，只为给定的图像API编译该Shader，包括OpenGL 3.x/4.x 、OpenGL ES 2.0/3.x 、D3D 11/12#pragma target 2.0 //指定shader program应用的最低等级的shader model，2.0适用于 Unity 支持的所有平台。DX9 着色器模型 2.0。 有限数量的算术和纹理指令；8 个插值器；没有顶点纹理采样；片元着色器中没有衍生指令；没有显式的 LOD 纹理采样。////--------------------------------------// GPU Instancing#pragma multi_compile_instancing//着色器变体编译指令，使该Shader支持GPU Instancing功能，#pragma instancing_options renderinglayer//指定所有实例化后的对象的渲染层级// -------------------------------------// Material Keywords //#pragma shader_feature_local表示定义local keywords，后缀_fragment表示关键字用于片元着色器阶段，这些关键字与材质面板上的参数有关，遇到的时候再解释//关键字的名字前一般要带下划线#pragma shader_feature_local _NORMALMAP#pragma shader_feature_local _PARALLAXMAP#pragma shader_feature_local _RECEIVE_SHADOWS_OFF#pragma shader_feature_local _ _DETAIL_MULX2 _DETAIL_SCALED#pragma shader_feature_local_fragment _SURFACE_TYPE_TRANSPARENT#pragma shader_feature_local_fragment _ALPHATEST_ON#pragma shader_feature_local_fragment _ALPHAPREMULTIPLY_ON#pragma shader_feature_local_fragment _EMISSION#pragma shader_feature_local_fragment _METALLICSPECGLOSSMAP#pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A#pragma shader_feature_local_fragment _OCCLUSIONMAP#pragma shader_feature_local_fragment _SPECULARHIGHLIGHTS_OFF#pragma shader_feature_local_fragment _ENVIRONMENTREFLECTIONS_OFF#pragma shader_feature_local_fragment _SPECULAR_SETUP// -------------------------------------// Universal Pipeline keywords// #pragma multi_compile表示global keywords，与shader_feature的区别是， Unity只为shader_feature中使用的关键字编译着色器变体shader variant#pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN//一次声明多个关键字#pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS#pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS#pragma multi_compile_fragment _ _SHADOWS_SOFT#pragma multi_compile_fragment _ _SCREEN_SPACE_OCCLUSION#pragma multi_compile_fragment _ _DBUFFER_MRT1 _DBUFFER_MRT2 _DBUFFER_MRT3#pragma multi_compile_fragment _ _REFLECTION_PROBE_BLENDING#pragma multi_compile_fragment _ _REFLECTION_PROBE_BOX_PROJECTION#pragma multi_compile_fragment _ _LIGHT_LAYERS#pragma multi_compile_fragment _ _LIGHT_COOKIES#pragma multi_compile _ _CLUSTERED_RENDERING// -------------------------------------// Unity defined keywords#pragma multi_compile _ LIGHTMAP_SHADOW_MIXING#pragma multi_compile _ SHADOWS_SHADOWMASK#pragma multi_compile _ DIRLIGHTMAP_COMBINED#pragma multi_compile _ LIGHTMAP_ON#pragma multi_compile_fog#pragma multi_compile_fragment _ DEBUG_DISPLAY//定义顶点和片元着色器#pragma vertex LitPassVertex #pragma fragment LitPassFragment//添加引用文件，该Pass没有变量声明、顶点着色器函数、片元着色器函数，这些代码在引用的两个文件中#include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"#include "Packages/com.unity.render-pipelines.universal/Shaders/LitForwardPass.hlsl"ENDHLSL}