Macros

ShaderLab supports some macros and macro operators from the standard GLSL syntax:

#define
#undef
#if
#ifdef
#ifndef
#else
#elif
#endif
defined

and the additionally introduced #include macro.

ShaderLab macros are expanded during the preprocessor stage, so macros cannot affect ShaderLab structure parsing. Keywords such as Shader, SubShader, Pass, EditorProperties, and EditorMacros cannot be included within branch macros like #ifdef.

include Macro

To facilitate code reuse, the include macro can be used in ShaderLab to reference code segments, which will be automatically expanded and replaced during subsequent compilation.

#include "{includeKey}"

To enable code segments to be referenced via the include macro, we have two ways to declare code segments:

Create Shader / Shader Fragment in the editor

The includeKey for the created code segment is the file path of the file in the project, such as /Root/Effect.glsl.

Explicitly register code segments in the script

import { ShaderFactory } from '@galacean/engine';
 
const commonSource = `// shader chunk`;
ShaderFactory.registerInclude('includeKey', commonSource);

Shader file inclusion supports relative path references. All relative paths are converted based on the main Shader file path. For example, if the Shader file path is /root/hair/shader.gs and the included code segment path is /root/hair/common.glsl, the relative path for inclusion would be #include "./common.glsl".

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include Macro