README

moon_wgsl

WGSL preprocess and composer utilities aligned with naga_oil.

wgsl

shader

Download zip

Author

Milky2018

Version

0.13.0

License

Apache-2.0

Repository

github.com/moonbit-community/moon_wgsl

Last updated

5 months ago

Downloads

393

#moon_wgsl

Milky2018/moon_wgsl is a MoonBit library for composing WGSL shader modules with naga_oil-style preprocessing and imports.

Use it when your shaders contain directives such as #define_import_path, #ifdef, #define, and #import, and you want to resolve them from MoonBit without adding a separate shader build step.

#Install

Add the package from Mooncakes, then import the subpackages you need:

///|
test "README: package is available" {
  let value_defines = @common.default_wgsl_value_defines()
  debug_inspect(value_defines.length() > 0, content="true")
}

Most users only need these packages:

@common for shared option and result types
@metadata for inspecting directives and imports
@preprocess for evaluating one shader source
@resolver for source registries and source-tree scanning
@compose for module composition
@export for single-file export

#Features

Conditional preprocessing: #ifdef, #ifndef, #if, #else if, #else, and #endif
Shader definition values: bools, signed integers, unsigned integers, and raw WGSL text values
Grouped, aliased, and quoted-path imports
Composer-owned source registries for hermetic composition
Optional source-tree scanning through moonbitlang/x/fs
Single-file WGSL export with source catalog, source map, provenance, and diagnostics

#Quick Start

#Compose Modules

///|
test "README: compose registered modules" {
  let composer : @compose.Composer = @compose.Composer::default()
  composer.clear_sources()

  composer.register_source(
    "maths.wgsl", "#define_import_path demo::maths\nconst TWO: f32 = 2.0;\n",
  )
  composer.register_source(
    "main.wgsl", "#import demo::maths::TWO\nfn scale(x: f32) -> f32 {\n  return x * TWO;\n}\n",
  )

  let options : @common.WgslComposeOptions = @common.WgslComposeOptions::default()
  let composed = composer.compose_wgsl("main.wgsl", options) catch {
    err => abort(err.message())
  }

  debug_inspect(composed.contains("fn scale"), content="true")
  debug_inspect(composed.contains("#import"), content="false")
}

#Preprocess One Shader

Use Preprocessor::preprocess when you only need conditional compilation and shader-definition substitution for a single source string.

///|
test "README: preprocess one shader" {
  let defs : Map[String, @common.ShaderDefValue] = Map([])
  defs.set("TEXTURE", @common.ShaderDefValue::Bool(true))

  let source = "#ifdef TEXTURE\nvar sprite_texture: texture_2d<f32>;\n#else\nvar sprite_texture: texture_2d_array<f32>;\n#endif\n"
  let output = @preprocess.Preprocessor::default().preprocess(source, defs) catch {
    _ => abort("preprocess failed")
  }

  debug_inspect(
    output.preprocessed_source.contains("texture_2d<f32>"),
    content="true",
  )
}

#Read Metadata

Use metadata extraction when you want to inspect a shader before composing it.

///|
test "README: inspect metadata" {
  let source = "#define_import_path demo::main\n#define HDR\n#import demo::maths::TWO\nfn scale(x: f32) -> f32 {\n  return x * TWO;\n}\n"
  let metadata = @metadata.get_preprocessor_metadata(source) catch {
    _ => abort("metadata extraction failed")
  }

  debug_inspect(metadata.name, content="Some(\"demo::main\")")
  debug_inspect(metadata.imports.length(), content="1")
}

#Export One File

Use export_wgsl_with_options to compose and tree-shake a root shader into one WGSL file.

///|
test "README: export single file" {
  let composer : @compose.Composer = @compose.Composer::default()
  composer.clear_sources()
  composer.register_source(
    "shared.wgsl", "#define_import_path demo::shared\nstruct Value {\n  x: f32,\n}\nfn read(value: Value) -> f32 {\n  return value.x;\n}\n",
  )
  composer.register_source(
    "main.wgsl", "#import demo::shared::{Value, read}\nfn shade(value: Value) -> f32 {\n  return read(value);\n}\n",
  )

  let compose_options : @common.WgslComposeOptions = @common.WgslComposeOptions::default()
  let export_options : @common.WgslExportOptions = { root_items: ["shade"] }
  let output = @export.export_wgsl_with_options(
    composer, "main.wgsl", compose_options, export_options,
  ) catch {
    err => abort(err.message())
  }

  debug_inspect(output.source.contains("#import"), content="false")
  debug_inspect(output.source.contains("fn shade"), content="true")
  debug_inspect(output.diagnostics.length(), content="0")
}

#Import Syntax

The supported import forms match common naga_oil usage:

#import bevy_render::view::View
#import bevy_render::maths as maths
#import bevy_render::{view::View, globals::Globals}
#import bevy_render::{maths::{PI_2, powsafe}}
#import "shaders/skills/shared.wgsl" Vertex, VertexOutput
#import "../shared/common.wgsl" SharedVertex, build_color

Relative quoted imports are resolved against the registered path of the importing shader.

#Recommended APIs

@compose.Composer::default
Composer::register_source
Composer::register_source_files
Composer::register_source_tree
Composer::compose_wgsl
@preprocess.Preprocessor::default
Preprocessor::preprocess
@metadata.get_preprocessor_metadata
@resolver.scan_wgsl_source_files
@resolver.scan_wgsl_source_files_checked
@export.export_wgsl_with_options

Important option/result types live in @common, including:

WgslComposeOptions
WgslExportOptions
WgslSourceFile
WgslSourceScanOptions
PreprocessOutput
PreprocessorMetaData
PreparedWgslSource
WgslExportOutput
WgslDiagnostic
ShaderDefValue

#Compatibility

The library aims to preserve the practical naga_oil programming model used by real shader pipelines. Internally, composition uses structured parsing, symbol-identity-aware binding, and an IR-backed validation pipeline before returning runtime-oriented WGSL.

For implementation details and parity status, see:

#Development

Run the test suite from the module root:

moon test

#License

Apache-2.0

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