OpenLIME

Class: LayerCombiner

LayerCombiner

LayerCombiner provides functionality to combine multiple layers using framebuffer operations and custom shaders. It enables complex visual effects by compositing layers in real-time using GPU-accelerated rendering.

Features:

  • Real-time layer composition
  • Custom shader-based effects
  • Framebuffer management
  • Dynamic texture allocation
  • Resolution-independent rendering
  • GPU-accelerated compositing

Use Cases:

  • Layer blending and mixing
  • Image comparison tools
  • Lens effects (see LayerLens)
  • Custom visual effects
  • Multi-layer compositing

Technical Details:

  • Creates framebuffers for each input layer
  • Manages WebGL textures and resources
  • Supports dynamic viewport resizing
  • Handles shader-based composition
  • Maintains proper resource cleanup

new LayerCombiner(options)

Creates a new LayerCombiner instance

Parameters:
Name Type Description
options LayerCombinerOptions

Configuration options
Source:
Throws:

If rasters option is not empty (rasters should be defined in source layers)

Type
Error
Example
```javascript
// Create two base layers
const baseLayer = new OpenLIME.Layer({
  type: 'image',
  url: 'base.jpg'
});

const overlayLayer = new OpenLIME.Layer({
  type: 'image',
  url: 'overlay.jpg'
});

// Create combiner with custom shader
const combiner = new OpenLIME.Layer({
  type: 'combiner',
  layers: [baseLayer, overlayLayer],
  visible: true
});

// Set up blend shader
const shader = new OpenLIME.ShaderCombiner();
shader.mode = 'blend';
combiner.shaders = { 'standard': shader };
combiner.setShader('standard');

// Add to viewer
viewer.addLayer('combined', combiner);
```

Extends

Methods

addControl(name, value)

Adds a shader parameter control

Parameters:
Name Type Description
name string

Control identifier
value *

Initial value
Inherited From:
Overrides:
Source:
Throws:

If control already exists

Type
Error

addShaderFilter(filter)

Adds a filter to the current shader

Parameters:
Name Type Description
filter Object

Filter specification
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

clearShaderFilters(name)

Removes all filters from the current shader

Parameters:
Name Type Description
name Object

Filter name
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

getControl(name)

Gets the shader parameter control corresponding to name

Parameters:
Name Type Description
name *

The name of the control. return {*} The control
Inherited From:
Overrides:
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getMode()

Gets the current shader visualization mode

Inherited From:
Overrides:
Source:
Returns:

Current mode or null if no shader

Type
string | null

getModes()

Gets available shader modes

Inherited From:
Overrides:
Source:
Returns:

Array of available modes

Type
Array.<string>

getState( [stateMask])

Gets the current layer state

Parameters:
Name Type Argument Default Description
stateMask Object <optional>
 null

Optional mask to filter returned state properties
Inherited From:
Overrides:
Source:
Returns:

Current state object

Type
Object

interpolateControls()

Updates control interpolation

Inherited From:
Overrides:
Source:
Returns:

Whether all interpolations are complete

Type
boolean

pixelSizePerMM()

Gets pixel size in millimeters

Inherited From:
Overrides:
Source:
Returns:

Size of one pixel in mm

Type
number

removeShaderFilter(name)

Removes a filter from the current shader

Parameters:
Name Type Description
name Object

Filter name
Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

setControl(name, value [, dt] [, easing])

Sets a shader control value with optional animation

Parameters:
Name Type Argument Default Description
name string

Control identifier
value *

New value
dt number <optional>

Animation duration in ms
easing string <optional>
 'linear'

Easing function
Inherited From:
Overrides:
Source:
Fires:

setMode(mode)

Sets shader visualization mode

Parameters:
Name Type Description
mode string

Mode to set
Inherited From:
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Fires:

setShader(id)

Sets the active shader

Parameters:
Name Type Description
id string

Shader identifier from registered shaders
Inherited From:
Overrides:
Source:
Fires:
Throws:

If shader ID is not found

Type
Error

setState(state [, dt] [, easing])

Sets the layer state with optional animation

Parameters:
Name Type Argument Default Description
state Object

State object with controls and mode
dt number <optional>

Animation duration in ms
easing string <optional>
 'linear'

Easing function ('linear'|'ease-out'|'ease-in-out')
Inherited From:
Overrides:
Source:

setTransform(tx)

Sets the layer's transform

Parameters:
Name Type Description
tx Transform

New transform
Inherited From:
Overrides:
Source:
Fires:
  • Layer#event:updateSize

setViewport(view)

Sets the layer's viewport

Parameters:
Name Type Description
view Object

Viewport specification

Properties
Name Type Description
x number

X position
y number

Y position
dx number

Width
dy number

Height
Inherited From:
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setVisible(visible)

Sets layer visibility

Parameters:
Name Type Description
visible boolean

Whether layer should be visible
Inherited From:
Overrides:
Source:
Fires:

setZindex(zindex)

Sets layer rendering order

Parameters:
Name Type Description
zindex number

Stack order value
Inherited From:
Overrides:
Source:
Fires:

Events

ready

The event is fired when a layer is initialized.

Inherited From:
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update

The event is fired if a redraw is needed.

Inherited From:
Overrides:
Source: