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Model

A Group is a subclass of ScenegraphNode that holds a reference to a mesh with a transformation matrix that describes its position and orientation.

A Model holds all the data necessary to draw an object, e.g.:

  • shaders (via a Program instance)
  • uniforms these can also reference textures.
  • vertex attributes (holds a [Mesh] or a Geometry instance, plus any additional attributes for instanced rendering)

The Model class also provides the following features:

  • Shader Module integration: see Shader Modules
  • Automatic creation of GPU Buffers from typed array attributes
  • Detailed debug logging of draw calls
  • Exposes the functionality provided by the managed WebGL resources
  • Animation of uniforms
  • Detailed stats including timing of draw calls

Usage

Provide attribute data using Geometry object

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

// construct the model.
const model =  new Model(gl, {
  vs: VERTEX_SHADER,
  fs: FRAGMENT_SHADER,
  uniforms: {uSampler: texture},
  geometry: geometryObject,
})

// and on each frame update any uniforms (typically matrices) and call render.
model
  .setUniforms({
    uPMatrix: currentProjectionMatrix,
    uMVMatrix: current ModelViewMatrix
  })
  .draw();

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(gl, {
  vs: VERTEX_SHADER,
  fs: FRAGMENT_SHADER,
  uniforms: {uSampler: texture},
  attributes: {
    attributeName1: bufferObject,
    attributeName2: [new Buffer(gl, new Float32Array(...)), {size: 3, type: GL.FLOAT}]
  }
  drawMode: gl.TRIANGLE_FAN,
  vertexCount: 3,
})

// and on each frame update any uniforms (typically matrices) and call render.
model
  .setUniforms({
    uPMatrix: currentProjectionMatrix,
    uMVMatrix: current ModelViewMatrix
  })
  .draw();

Provide attribute data using VertexArray object

A VertexArray object can be build and passed to Model.draw() to provide attribute data. Attribute data can be changed by changing VertexArray object.

// construct the model.
const model =  new Model(gl, {
  vs: VERTEX_SHADER,
  fs: FRAGMENT_SHADER,
  uniforms: {uSampler: texture},
  drawMode: gl.TRIANGLE_FAN,
  vertexCount: 3,
})

const ATTRIBUTE1_LOCATION = 0;
const ATTRIBUTE2_LOCATION = 1;
const vertexArray1 = new VertexArray(gl, {
  buffers: {
    [ATTRIBUTE1_LOCATION]: buffer1,
    [ATTRIBUTE2_LOCATION]: buffer2
  }
});
const vertexArray2 = new VertexArray(gl, {
  buffers: {
    [ATTRIBUTE1_LOCATION]: buffer3,
    [ATTRIBUTE2_LOCATION]: buffer4
  }
});

//Render using attribute data from vertexArray1.
model.draw({
  uniforms: {
    uPMatrix: currentProjectionMatrix,
    uMVMatrix: currentModelViewMatrix
  },
  vertexArray: vertexArray1
});

// Switch attribute data to vertexArray2
model.draw({
  uniforms: {
    uPMatrix: currentProjectionMatrix,
    uMVMatrix: currentModelViewMatrix
  },
  vertexArray: vertexArray2
});

Properties

Model extends the BaseModel class and inherits all properties from that class.

moduleSettings : Object

any uniforms needed by shader modules.

uniforms : Object

uniform values to be used for drawing.

onBeforeRender

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

onAfterRender

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

mesh

Mesh instance.

Deprecated Properties in v7

geometry

Geometry object, from which attributes, vertex count and drawing mode are deduced.

isInstanced : Boolean

default value is false.

instanceCount : Number

default value is 0.

vertexCount : Number

when not provided will be deduced from geometry object.

Constructor

Model(gl: WebGLRenderingContext, props: Object)

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

The following props can only be specified on construction:

  • vs - (VertexShader|string) - A vertex shader object, or source as a string.
  • fs - (FragmentShader|string) - A fragment shader object, or source as a string.
  • varyings (WebGL2) - An array of vertex shader output variables, that needs to be recorded (used in TransformFeedback flow).
  • bufferMode (WebGL2) - Mode to be used when recording vertex shader outputs (used in TransformFeedback flow). Default value is gl.SEPARATE_ATTRIBS.
  • modules - shader modules to be applied.
  • program - pre created program to use, when provided, vs, ps and modules are not used.
  • shaderCache - (ShaderCache) - Compiled shader (Vertex and Fragment) are cached in this object very first time they got compiled and then retrieved when same shader is used. When using multiple Model objects with duplicate shaders, use the same shaderCache object for better performance.

delete() : Model

Free WebGL resources associated with this model

Methods

setProps(props : Object) : Model

Updates properties

isAnimated() : Boolean

Returns true if the model is animated (i.e. needs to be redrawn every frame).

getProgram() : Program

Get model's Program instance

getUniforms() : Object

Returns map of currently stored uniforms

setUniforms(uniforms : Object) : Model

Stores named uniforms {key, value}

updateModuleSettings(moduleSettings : Object) : Model

draw(options : Object) : Model

Renders the model with provided uniforms, attributes and samplers

model.draw({
  moduleSettings = null,
  uniforms = {},
  attributes = {},
  samplers = {},
  parameters = {},
  settings,
  framebuffer = null,
  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.

transform(options : Object) : Model

Renders the model with provided uniforms, and samplers. Calls Program.draw() with rasterization turned off.

  • discard=true (Boolean) - Turns off rasterization
  • feedbackBuffers=null (Object) - Optional map of feedback buffers. A TransformFeedback object will be created, initialized with these buffers, and passed to Model.draw.
  • unbindModels=[] (Model[]) - Array of models whose VertexAttributes will be temporarily unbound during the transform feeback to avoid triggering a possible Khronos/Chrome bug. .
model.transform({
  discard:
});

Deprecated Methods in v7

getDrawMode() : Enum

Gets the WebGL drawMode

getVertexCount() : GLInt

Gets vertex count

Note: might be autocalculated from Geometry

getInstanceCount() : GLInt

Defaults to 0

getAttributes() : Object

Get a map of named attributes

setDrawMode() : Model

Sets the WebGL drawMode.

GL.POINTS etc.

setVertexCount() : Model

Sets the number of vertices

setInstanceCount() : Model

How many instances will be rendered

setGeometry() : Model

Use a Geometry instance to define attribute buffers

setAttributes(attributes : Object) : Model

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

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.