luma.gl/docs/api-reference/engine/model.md

Model

:::caution The luma.gl v9 API is currently in public review and may be subject to change. :::

The Model class is the centerpiece of the luma.gl API. It brings together all the different functionality needed to run shaders and perform draw calls in a single, easy-to-use interface.

• render pipeline creation -
• attributes
• bindings these can reference textures and uniform buffers
• uniforms WebGL only uniforms
• shader module injection
• shader transpilation**
• debugging - Detailed debug logging of draw calls

The Model class integrates with the @luma.gl/shadertools shader module system: see Shader Assembly.

(Accepts a [Mesh] or a [Geometry](/docs/- - api-reference/engine/geometry) instance, plus any additional attributes for instanced rendering)

Usage

import {Model} from `@luma.gl/engine`;

One of the simplest way to provide attribute data is by using a Geometry object.

Create model object by passing shaders, uniforms, geometry and render it by passing updated uniforms.

import {Model, CubeGeometry} from `@luma.gl/engine`;
// construct the model.
const model = new Model(device, {
  vs: VERTEX_SHADER,
  fs: FRAGMENT_SHADER,
  geometry: new CubeGeometry(),
  bindings: {
    uSampler: texture
  },
})

Provide attribute data using Buffer

When using Buffer objects, data remains on GPU and same Buffer object can be shared between multiple models.

// construct the model.
const model = new Model(device, {
  vs: VERTEX_SHADER,
  fs: FRAGMENT_SHADER,
  topology: 'triangle-list',
  vertexCount: 3,
  attributes: {
    attributeName1: bufferObject,
    attributeName2: device.createBuffer(new Float32Array(...))
  },
  uniforms: {uSampler: texture},
})

On each frame, call the model.draw() function after updating any uniforms (typically matrices).

model.setUniforms({
  uPMatrix: currentProjectionMatrix,
  uMVMatrix: current ModelViewMatrix
});
model.draw();

Types

ModelProps

Property	Type	Description
vs	Shader | string	A vertex shader object, or source as a string.
fs	Shader | string	A fragment shader object, or source as a string.
modules		shader modules to be applied (shadertools).
programManager		ProgramManager to use for program creation and caching.
varyings	(WebGL 2)	An array of vertex shader output variables, that needs to be recorded (used in TransformFeedback flow).
bufferMode	(WebGL 2)	Mode to be used when recording vertex shader outputs (used in TransformFeedback flow). Default value is GL.SEPARATE_ATTRIBS.
transpileToGLSL100		Transpile vertex and fragment shaders to GLSL 1.0.

ModelProps passes through RenderPipelineProps

Property	Type	Description
layout	ShaderLayout	Describes how shader attributes and bindings are laid out.
topology?		'point-list', 'line-list', 'line-strip', 'triangle-list' or 'triangle-strip',
parameters?	RenderPipelineParameters
Property	Type	Description
-----------------	------------------------	-------------------------------------------------------------------
vertexCount?	number
instanceCount?	number
moduleSettings?	Record<string, any>	any values required by shader modules (will be mapped to uniforms).
uniforms?	Record<string, any>	any non-binding uniform values
bindings?	Record<string, any>
buffers?	Record<string, Buffer>

Properties

renderPipeline: RenderPipeline

Get model's Program instance

onBeforeRender

function to be called before every time this model is drawn.

onAfterRender

function to be called after every time this model is drawn.

instanceCount: number

default value is 0.

vertexCount: number

when not provided will be deduced from geometry object.

Methods

constructor(device: Device, props: ModelProps)

The constructor for the Model class. Use this to create a new Model.

destroy(): void

Free GPU resources associated with this model immediately, instead of waiting for garbage collection.

draw(options: DrawOptions): boolean

Renders the model with provided uniforms, attributes and samplers

model.draw({
  renderPass,
  moduleSettings = null,
  uniforms = {},
  attributes = {},
  samplers = {},
  parameters = {},
  settings,
  vertexArray = null,
  transformFeedback = null
});

Model.draw() calls Program.draw() but adds and extends the available parameters as follows:

• moduleSettings=null (Object) - any uniforms needed by shader modules.
• attributes={} (Object) - attribute definitions to be used for drawing. In additions to Buffer and constant values, Models can also accept typed arrays and attribute descriptor objects which it converts to buffers.
• uniforms={} (Object) - uniform values to be used for drawing. In addition to normal uniform values, Model can also accept function valued uniforms which will be evaluated before every draw call.
• animationProps (Object) - if any function valued uniforms are set on the Model, animationProps must be provided to the draw call. The animationProps are passed as parameter to the uniform functions.

The remaining draw options are passed directly to Program.draw():

• uniforms={} (Object) - uniform values to be used for drawing.
• samplers={} (Object) - texture mappings to be used for drawing.
• parameters={} (Object) - temporary gl settings to be applied to this draw call.
• framebuffer=null (Framebuffer) - if provided, renders into the supplied framebuffer, otherwise renders to the default framebuffer.
• transformFeedback - an instance TranformFeedback object, that gets activated for this rendering.
• vertexArray - an instance of VertexArray object, that holds required buffer bindings for vertex shader inputs.

setDrawMode(); this

Sets the WebGL drawMode.

GL.POINTS etc.

setVertexCount(); this

Sets the number of vertices

setInstanceCount(); this

How many instances will be rendered

setGeometry(); this

Use a Geometry instance to define attribute buffers

setAttributes(attributes: object); this

Sets map of attributes (passes through to VertexArray.setAttributes)

setUniforms(uniforms: object): void

Stores named uniforms key, value

updateModuleSettings(moduleSettings: object): void

Remarks

• The Model class is arguably the most useful class for typical applications. It manages the WebGL resources needed to perform draw calls and provide additional functionality as described below.