Predefined Shader preprocessor macros //预定义的着色器预处理宏

https://blog.csdn.net/u013889563/article/details/74481496

Predefined Shader preprocessor macros 预定义的着色器预处理宏

Unity defines several preprocessor macros when compiling Shader programs.

在编译着色程序时，Unity定义了几个预处理器宏。

Target platform 

• 目标平台

SHADER_API_MOBILE is defined for all general mobile platforms (GLES, GLES3, METAL, PSP2).

为所有通用移动平台(GLES、GLES3、金属、PSP2)定义了shaderapimobile。

Additionally, SHADER_TARGET_GLSL is defined when the target shading language is GLSL (always true for OpenGL/GLES platforms).

另外，当目标着色语言是GLSL时(对于面向对象的/gles平台来说总是正确的)，定义着色目标tglsl。

Shader target model 着色器目标模型

SHADER_TARGET is defined to a numeric value that matches the Shader target compilation model (that is, matching #pragma target directive). For example,SHADER_TARGET is 30 when compiling into Shader model 3.0. You can use it in Shader code to do conditional checks. For example:

shadertarget被定义为与着色器目标编译模型匹配的数值(也就是匹配目标指令指令)。例如，当编译成Shader模型3.0时，shadertarget是30。您可以在着色器代码中使用它来进行条件检查。例如:

1. #if SHADER_TARGET < 30

2. // less than Shader model 3.0:

3. // very limited Shader capabilities, do some approximation

4. #else

5. // decent capabilities, do a better thing

6. #endif

Unity version 

• 版本

UNITY_VERSION contains the numeric value of the Unity version. For example, UNITY_VERSION is 501 for Unity 5.0.1. This can be used for version comparisons if you need to write Shaders that use different built-in Shader functionality. For example, a #if UNITY_VERSION >= 500 preprocessor check only passes on versions 5.0.0 or later.

unityversion包含Unity版本的数值。例如，unityversion是501，用于统一5.0.1。如果您需要编写使用不同内置着色器功能的着色器，那么可以将其用于版本比较。例如，如果unityversion=500预处理器检查只通过版本5.0.0或更高版本。

Shader stage being compiled 着色器阶段被编译

Preprocessor

• 预处理器

macros SHADER_STAGE_VERTEX, SHADER_STAGE_FRAGMENT, SHADER_STAGE_DOMAIN, SHADER_STAGE_HULL, SHADER_STAGE_GEOMETRY, SHADER_STAGE_COMPUTE are defined when compiling each Shader stage. Typically they are useful when sharing Shader code between pixel Shaders and compute Shaders, to handle cases where some things have to be done slightly differently.

• 宏指令

SHADER_STAGE_VERTEX, SHADER_STAGE_FRAGMENT, SHADER_STAGE_DOMAIN, SHADER_STAGE_HULL, SHADER_STAGE_GEOMETRY, SHADER_STAGE_COMPUTE

在编译每个着色器阶段时都被罚款。通常，当在像素着色器和计算着色器之间共享着色的代码时，它们是很有用的，以处理一些需要稍微改变一些事情的情况。

Platform difference helpers 平台差异助手

Direct use of these platform macros is discouraged, as they don’t always contribute to the future-proofing of your code. For example, if you’re writing a Shader that checks for D3D9, you may want to ensure that, in the future, the check is extended to include D3D11. Instead, Unity defines several helper macros (inHLSLSupport.cginc):

直接使用这些平台宏是不鼓励的，因为它们并不总是对代码的未来有所帮助。例如，如果您正在编写一个用于检查D3D9的着色器，那么您可能希望确保在将来，该检查被扩展为包含D3D11。相反，Unity定义了几个助手宏(inHLSLSupport.cginc):

• UNITY_REVERSED_Z - defined on plaftorms using reverse Z buffer. Stored Z values are in the range 1..0 instead of 0..1.
• UNITY_REVERSED_Z在plaftorms上使用反向Z缓冲区定义。存储的Z值在范围1中。0 0 . . 1。

Shadow mapping macros 阴影映射宏

Declaring and sampling shadow maps can be very different depending on the platform. Unity has several macros to help with this:

根据平台的不同，声明和采样影子映射可能会非常不同。Unity有几个宏来帮助这个:

NOTE: Not all graphics cards support shadowmaps. Use SystemInfo.SupportsRenderTextureFormat to check for support.

Constant buffer macros 常数缓冲宏

Direct3D 11 groups all Shader variables into “constant buffers”. Most of Unity’s built-in variables are already grouped, but for variables in your own Shaders it might be more optimal to put them into separate constant buffers depending on expected frequency of updates.

所有群组11 Direct3D Shader变量纳入“constant缓冲池”。协调统一的built-in变量,但已经是grouped for your own变量在Shaders it more to be可能optimal put them on可供缓冲constant单独考虑预期的《frequency更新。

Use CBUFFER_START(name) and CBUFFER_END macros for that:

使用cbufferstart(name)和cbufferend宏:

1. CBUFFER_START(MyRarelyUpdatedVariables)

2. float4 _SomeGlobalValue;

3. CBUFFER_END

Texture/Sampler declaration macros 宏纹理/取样器声明

Usually you would use texture2D in Shader code to declare a Texture and Sampler pair. However on some platforms (such as DX11), Textures and Samplers are separate GameObjects, and maximum possible Sampler count is quite limited. Unity has some macros to declare Textures without Samplers, and to sample a Texture using a Sampler from another Texture. Use this if you end up running into Sampler limits, and you know that several of your Textures can in fact share a Sampler (Samplers define Texture filtering and wrapping modes).

通常你会在着色器代码中使用texture2D来声明纹理和采样对。但是在某些平台上(比如DX11)，纹理和采样器是独立的游戏对象，并且最大可能的采样计数是非常有限的。Unity有一些宏可以在没有采样器的情况下声明纹理，并使用来自另一个纹理的采样器来采样纹理。如果你最终进入了采样限制，你就知道你的一些纹理实际上可以共享一个采样器(Samplers定义了纹理过滤和包装模式)。

Surface Shader pass indicators 表面材质通过指标

When Surface Shaders are compiled, they generate a lot of code for various passes to do lighting. When compiling each pass, one of the following macros is defined:

当表面着色器被编译时，它们会生成大量的代码来进行各种各样的照明。在编译每个传递时，以下宏定义如下:

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