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ShaderModule

In luma.gl, reusable shader modules are defined by objects that conform to the ShaderModule type. For more information see Shader Module System Guide.

ShaderModules are used by the luma.gl shader assembler. The shader assembler imports chunks of reusable shader code from the module into your shader program source code.

Usage​

To define a new shader module, you create a descriptor object that brings together all the necessary pieces:

export const MY_SHADER_MODULE = {
  name: 'my-shader-module',
  vs: '...',
  fs: '...',
  inject: {},
  dependencies: [],
  deprecations: [],
  getUniforms
};

Fields​

name​

  • name (string) - The name of the shader module.

vs​

  • vs? - (string | null)

fs​

  • fs - (string | null)

uniforms (Object)​

inject (Object) - injections the module will make into shader hooks, see below​

dependencies (Array) - a list of other shader modules that this module is dependent on​

deprecations (Array) - a list of deprecated APIs.​

If deprecations is supplied, assembleShaders will scan shader source code for the deprecated constructs and issue a console warning if found. Each API is described in the following format:

  • type: uniform <type> or function
  • old: name of the deprecated uniform/function
  • new: name of the new uniform/function
  • deprecated: whether the old API is still supported.

Defining Uniforms​

If the uniforms of this module can be directly pulled from user settings, they may declaratively defined by a uniforms object:

{
  name: 'my-shader-module',
  uniforms: {
    strength: {type: 'number', value: 1, min: 0, max: 1},
    center: [0.5, 0.5]
  }
}

At runtime, this map will be used to generate the uniforms needed by the shaders. If either strength or center is present in the user's module settings, then the user's value will be used; otherwise, the default value in the original definition will be used.

Each uniform definition may contain the following fields:

  • type (string number, boolean, array or object
  • value - the default value of this uniform

With type: 'number', the following additional fields may be added for validation:

  • min (Number)
  • max (Number)

Note: uniforms is ignored if getUniforms is provided.

Defining Injections​

A map of hook function signatures to either the injection code string, or an object containing the injection code and an order option indicating ordering within the hook function. See assembleShaders documentation for more information on shader hooks.

For example:

{
  picking: {
    'vs:VERTEX_HOOK_FUNCTION': 'picking_setPickingColor(color.rgb);',
    'fs:FRAGMENT_HOOK_FUNCTION': {
      injection: 'color = picking_filterColor(color);',
      order: Number.POSITIVE_INFINITY
    },
    'fs:#main-end': 'gl_FragColor = picking_filterColor(gl_FragColor);'
  }
}

Functions​

getShaderModuleUniforms()​

getShaderModuleUniforms(module: ShaderModule)
  • JavaScript function that maps JavaScript parameter keys to uniforms used by this module

Each shader module provides a method to get a map of uniforms for the shader. This function will be called with two arguments:

  • opts - the module settings to update. This argument may not be provided when getUniforms is called to generate a set of default uniform values.
  • context - the uniforms generated by this module's dependencies.

The function should return a JavaScript object with keys representing uniform names and values representing uniform values.

The function should expect the shape of the dependency uniforms to vary based on what's passed in opts. This behavior is intended because we only want to recalculate a uniform if the uniforms that it depends on are changed. An example is the project and project64 modules in deck.device. When opts.viewport is provided, project64 will receive the updated projection matrix generated by the project module. If opts.viewport is empty, then the project module generates nothing and so should project64

getShaderModuleDependencies()​

getShaderModuleDependencies(module: ShaderModule): ShaderModule[]

TODO​

caution

This page is not complete:

  • Describe props to uniforms mapping system
  • Better documentation of getShaderModuleUniforms
  • Describe all functions working on shader modules
  • Better reference information for injections