engine/src/flutter/impeller/shader_bundle/shader_bundle.fbs

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

namespace impeller.fb.shaderbundle;

// This is the shader bundle format version number - it's value should be
// incremented any time there is a change to this file which changes the
// resulting flat buffer format.
enum ShaderBundleFormatVersion:uint32 {
  kVersion = 2
}

enum ShaderStage:byte {
  kVertex,
  kFragment,
  kCompute,
}

// The subset of impeller::ShaderType that may be used for vertex attributes.
enum InputDataType:uint32 {
  kBoolean,
  kSignedByte,
  kUnsignedByte,
  kSignedShort,
  kUnsignedShort,
  kSignedInt,
  kUnsignedInt,
  kSignedInt64,
  kUnsignedInt64,
  kFloat,
  kDouble,
}

// The subset of impeller::ShaderType that may be used for uniform bindings.
enum UniformDataType:uint32 {
  kBoolean,
  kSignedByte,
  kUnsignedByte,
  kSignedShort,
  kUnsignedShort,
  kSignedInt,
  kUnsignedInt,
  kSignedInt64,
  kUnsignedInt64,
  kHalfFloat,
  kFloat,
  kDouble,
  kSampledImage,
}

// This contains the same attribute reflection data as
// impeller::ShaderStageIOSlot.
table ShaderInput {
  name: string;
  location: uint64;
  set: uint64;
  binding: uint64;
  type: InputDataType;
  bit_width: uint64;
  vec_size: uint64;
  columns: uint64;
  offset: uint64;
}

table ShaderUniformStructField {
  name: string;
  type: UniformDataType;
  offset_in_bytes: uint64;
  element_size_in_bytes: uint64;
  total_size_in_bytes: uint64;
  // Zero indicates that this field is not an array element.
  array_elements: uint64;
  // The number of components per column. For a vector this is the vector
  // length; for a matrix this is the row count. Combined with `columns`, this
  // disambiguates types that share the same `element_size_in_bytes`, e.g.
  // vec4 and mat2.
  vec_size: uint64;
  // The number of columns. 1 for scalars and vectors; N for an NxN matrix.
  columns: uint64;
}

table ShaderUniformStruct {
  name: string;
  ext_res_0: uint64;
  set: uint64;
  binding: uint64;
  size_in_bytes: uint64; // Includes all alignment padding.
  fields: [ShaderUniformStructField];
}

table ShaderUniformTexture {
  name: string;
  ext_res_0: uint64;
  set: uint64;
  binding: uint64;
}

table BackendShader {
  stage: ShaderStage;
  entrypoint: string;
  inputs: [ShaderInput];
  uniform_structs: [ShaderUniformStruct];
  uniform_textures: [ShaderUniformTexture];
  shader: [ubyte];
}

table Shader {
  name: string;
  metal_ios: BackendShader;
  metal_desktop: BackendShader;
  opengl_es: BackendShader;
  opengl_desktop: BackendShader;
  vulkan: BackendShader;
}

table ShaderBundle {
  shaders: [Shader];
  format_version: uint32;  // This is intended to hold ShaderBundleFormatVersion.kVersion.
}

root_type ShaderBundle;
file_identifier "IPSB";