# WebGPU Shading Language Reflection Library

A WebGPU Shading Language parser and reflection library for Typescript and Javascript.

**wgsl_reflect** can parse a WGSL shader and analyze its contents, providing information about the shader. It can determine the bind group layout of the shader, resource bindings, uniform buffers, the members of a uniform buffer, their names, types, sizes, offsets into the buffer.

## Usage

From NPM
```
npm install wgsl_reflect
```

The _wgsl_reflect.module.js_ file is a self-contained roll-up of the library that can be included in your project and imported with:

```javascript
import { WgslReflect } from "wgsl_reflect/wgsl_reflect.module.js";
const reflect = new WgslReflect(shader_code);
```

## Example

[WGSL Reflect Example](https://brendan-duncan.github.io/wgsl_reflect/example.html)

## Documentation

```javascript
class WgslReflect {
  /// All top-level uniform vars in the shader.
  uniforms: Array<VariableInfo>;
  /// All top-level storage vars in the shader, including storage buffers and textures.
  storage: Array<VariableInfo>;
  /// All top-level texture vars in the shader;
  textures: Array<VariableInfo>;
  // All top-level sampler vars in the shader.
  samplers: Array<VariableInfo>;
  /// All top-level type aliases in the shader.
  aliases: Array<AliasInfo>;
  /// All top-level overrides in the shader.
  overrides: Array<OverrideInfo> = [];
  /// All top-level structs in the shader.
  structs: Array<StructInfo>;
  /// All entry functions in the shader: vertex, fragment, and/or compute.
  entry: EntryFunctions;
  /// All functions in the shader, including entry functions.
  functions: Array<FunctionInfo>;

  // Find a resource by its group and binding.
  findResource(group: number, binding: number): VariableInfo | null;

  // Get the bind groups used by the shader, bindGroups[group][binding].
  getBindGroups(): Array<Array<VariableInfo>>;
}

enum ResourceType {
  Uniform,
  Storage,
  Texture,
  Sampler,
  StorageTexture
}

class VariableInfo {
  name: string; // The name of the variable
  type: TypeInfo; // The type of the variable
  group: number; // The binding group of the variable
  binding: number; // The binding index of the variable
  resourceType: ResourceType; // The resource type of the variable
  access: string; // "", read, write, read_write

  get isArray(): boolean; // True if it's an array type
  get isStruct(): boolean;  // True if it's a struct type
  get isTemplate(): boolean; // True if it's a template type
  get size(): number; // Size of the data, in bytes
  get align(): number; // The alignment size if it's a struct, otherwise 0
  get members(): Array<MemberInfo> | null; // The list of members if it's a struct, otherwise null
  get format(): TypeInfo | null; // The format if it's a template or array, otherwise null
  get count(): number; // The array size if it's an array, otherwise 0
  get stride(): number; // The array stride if it's an array, otherwise 0
}

class TypeInfo {
  name: string;
  size: number; // Size of the data, in bytes

  get isArray(): boolean;
  get isStruct(): boolean;
  get isTemplate(): boolean;
}

class StructInfo extends TypeInfo {
  members: Array<MemberInfo>;
  align: number;
  startLine: number;
  endLine: number;
  inUse: boolean; // true if the struct is used by a uniform, storage, or directly or indirectly by an entry function.
}

class ArrayInfo extends TypeInfo {
  format: TypeInfo;
  count: number;
  stride: number;
}

class TemplateInfo extends TypeInfo {
  format: TypeInfo;
  access: string; // "", read, write, read_write
}

class MemberInfo {
  name: string;
  type: TypeInfo;
  offset: number;
  size: number;

  get isArray(): boolean;
  get isStruct(): boolean;
  get isTemplate(): boolean;
  get align(): number;
  get members(): Array<MemberInfo> | null;
  get format(): TypeInfo | null;
  get count(): number;
  get stride(): number;
}

class AliasInfo {
  name: string;
  type: TypeInfo;
}

class EntryFunctions {
  vertex: Array<FunctionInfo>;
  fragment: Array<FunctionInfo>;
  compute: Array<FunctionInfo>;
}

class FunctionInfo {
  name: string;
  stage: string | null;
  inputs: Array<InputInfo>;
  outputs: Array<OutputInfo>;
  arguments: Array<ArgumentInfo>; // only for non-entry functions
  returnType: TypeInfo | null;
  resources: Array<VariableInfo>;
  startLine: number;
  endLine: number;
  inUse: boolean;  // true if called directly or indirectly by an entry function.
  calls: Set<FunctionInfo>; // All custom functions called directly by this function.
}

class InputInfo {
  name: string;
  type: TypeInfo | null;
  locationType: string;
  location: number | string;
  interpolation: string | null;
}

class OutputInfo {
  name: string;
  type: TypeInfo | null;
  locationType: string;
  location: number | string;
}

class OverrideInfo {
  name: string;
  type: TypeInfo | null;
  id: number;
}

class ArgumentInfo {
  name: string;
  type: TypeInfo;
}
```

## Examples

Calculate the bind group information in the shader:

```javascript
import { WgslReflect } from "./wgsl_reflect.module.js";

const shader = `
struct ViewUniforms {
    viewProjection: mat4x4<f32>
}

struct ModelUniforms {
    model: mat4x4<f32>,
    color: vec4<f32>,
    intensity: f32
}

@binding(0) @group(0) var<uniform> viewUniforms: ViewUniforms;
@binding(1) @group(0) var<uniform> modelUniforms: ModelUniforms;
@binding(2) @group(0) var u_sampler: sampler;
@binding(3) @group(0) var u_texture: texture_2d<f32>;

struct VertexInput {
    @location(0) a_position: vec3<f32>,
    @location(1) a_normal: vec3<f32>,
    @location(2) a_color: vec4<f32>,
    @location(3) a_uv: vec2<f32>
}

struct VertexOutput {
    @builtin(position) Position: vec4<f32>,
    @location(0) v_position: vec4<f32>,
    @location(1) v_normal: vec3<f32>,
    @location(2) v_color: vec4<f32>,
    @location(3) v_uv: vec2<f32>
}

@vertex
fn main(input: VertexInput) -> VertexOutput {
    var output: VertexOutput;
    output.Position = viewUniforms.viewProjection * modelUniforms.model * vec4<f32>(input.a_position, 1.0);
    output.v_position = output.Position;
    output.v_normal = input.a_normal;
    output.v_color = input.a_color * modelUniforms.color * modelUniforms.intensity;
    output.v_uv = input.a_uv;
    return output;
}`;

const reflect = new WgslReflect(shader);

console.log(reflect.functions.length); // 1
console.log(reflect.structs.length); // 4
console.log(reflect.uniforms.length); // 2

// Shader entry points
console.log(reflect.entry.vertex.length); // 1, there is 1 vertex entry function.
console.log(reflect.entry.fragment.length); // 0, there are no fragment entry functions.
console.log(reflect.entry.compute.length); // 0, there are no compute entry functions.

console.log(reflect.entry.vertex[0].name); // "main", the name of the vertex entry function.

console.log(reflect.entry.vertex[0].resources.length); // 2, main uses modelUniforms and viewUniforms resource bindings.
console.log(reflect.entry.vertex[0].resources[0].name); // viewUniforms
console.log(reflect.entry.vertex[0].resources[1].name); // modelUniforms

// Vertex shader inputs
console.log(reflect.entry.vertex[0].inputs.length); // 4, inputs to "main"
console.log(reflect.entry.vertex[0].inputs[0].name); // "a_position"
console.log(reflect.entry.vertex[0].inputs[0].location); // 0
console.log(reflect.entry.vertex[0].inputs[0].locationType); // "location" (can be "builtin")
console.log(reflect.entry.vertex[0].inputs[0].type.name); // "vec3"
console.log(reflect.entry.vertex[0].inputs[0].type.format.name); // "f32"

// Gather the bind groups used by the shader.
const groups = reflect.getBindGroups();
console.log(groups.length); // 1
console.log(groups[0].length); // 4, bindings in group(0)

console.log(groups[0][1].resourceType); // ResourceType.Uniform, the type of resource at group(0) binding(1)
console.log(groups[0][1].size); // 96, the size of the uniform buffer.
console.log(groups[0][1].members.length); // 3, members in ModelUniforms.
console.log(groups[0][1].members[0].name); // "model", the name of the first member in the uniform buffer.
console.log(groups[0][1].members[0].offset); // 0, the offset of 'model' in the uniform buffer.
console.log(groups[0][1].members[0].size); // 64, the size of 'model'.
console.log(groups[0][1].members[0].type.name); // "mat4x4", the type of 'model'.
console.log(groups[0][1].members[0].type.format.name); // "f32", the format of the mat4x4.

console.log(groups[0][2].resourceType); // ResourceType.Sampler

console.log(groups[0][3].resourceType); // ResourceType.Texture
console.log(groups[0][3].type.name); // "texture_2d"
console.log(groups[0][3].type.format.name); // "f32"
```

---

Calculate the member information for a uniform buffer block:

```javascript
import { WgslReflect } from "./wgsl_reflect.module.js";

// WgslReflect can calculate the size and offset for members of a uniform buffer block.

const shader = `
struct A {                                     //             align(8)  size(32)
    u: f32,                                    // offset(0)   align(4)  size(4)
    v: f32,                                    // offset(4)   align(4)  size(4)
    w: vec2<f32>,                              // offset(8)   align(8)  size(8)
    @size(16) x: f32                          // offset(16)  align(4)  size(16)
}

struct B {                                     //             align(16) size(208)
    a: vec2<f32>,                              // offset(0)   align(8)  size(8)
    // -- implicit member alignment padding -- // offset(8)             size(8)
    b: vec3<f32>,                              // offset(16)  align(16) size(12)
    c: f32,                                    // offset(28)  align(4)  size(4)
    d: f32,                                    // offset(32)  align(4)  size(4)
    // -- implicit member alignment padding -- // offset(36)            size(12)
    @align(16) e: A,                           // offset(48)  align(16) size(32)
    f: vec3<f32>,                              // offset(80)  align(16) size(12)
    // -- implicit member alignment padding -- // offset(92)            size(4)
    g: @stride(32) array<A, 3>,                // offset(96)  align(8)  size(96)
    h: i32,                                    // offset(192) align(4)  size(4)
    // -- implicit struct size padding --      // offset(196)           size(12)
}

@group(0) @binding(0)
var<uniform> uniform_buffer: B;`;

const reflect = new WgslReflect(shader);

const u = reflect.uniforms[0];
console.log(u.size); // 208, the size of the uniform buffer in bytes
console.log(u.group); // 0
console.log(u.binding); // 0
console.log(u.members.length); // 8, members in B
console.log(u.members[0].name); // "a"
console.log(u.members[0].offset); // 0, the offset of 'a' in the buffer
console.log(u.members[0].size); // 8, the size of 'a' in bytes
console.log(u.members[0].type.name); // "vec2", the type of 'a'
console.log(u.members[0].type.format.name); // "f32", the format of the vec2.

console.log(u.members[4].name); // "e"
console.log(u.members[4].offset); // 48, the offset of 'e' in the buffer
console.log(u.members[4].size); // 32, the size of 'e' in the buffer
```