OpenLIME

Class: LayerBRDF

LayerBRDF

LayerBRDF implements real-time BRDF (Bidirectional Reflectance Distribution Function) rendering.

The BRDF model describes how light reflects off a surface, taking into account:

  • Diffuse reflection (rough, matte surfaces)
  • Specular reflection (mirror-like reflections)
  • Surface normals (microscopic surface orientation)
  • Glossiness/roughness (surface micro-structure)

Features:

  • Real-time light direction control
  • Multiple material channels support
  • Customizable material properties
  • Interactive lighting model
  • Gamma correction
  • Ambient light component

Technical implementation:

  • Uses normal mapping for surface detail
  • Supports both linear and sRGB color spaces
  • Implements spherical light projection
  • Handles multi-channel textures
  • GPU-accelerated rendering

new LayerBRDF(options)

Creates a new LayerBRDF instance

Parameters:
Name Type Description
options LayerBRDFOptions

Configuration options
Source:
Throws:

  • If required channels (kd, normals) are not provided

    Type
    Error

  • If rasters option is not empty

    Type
    Error
Example
```javascript
// Create BRDF layer with all channels
const brdfLayer = new OpenLIME.LayerBRDF({
  channels: {
    kd: 'diffuse.jpg',
    ks: 'specular.jpg',
    normals: 'normals.jpg',
    gloss: 'gloss.jpg'
  },
  colorspaces: {
    kd: 'srgb',
    ks: 'linear'
  },
  brightness: 1.2,
  gamma: 2.2
});

// Update light direction
brdfLayer.setLight([0.5, 0.5], 500, 'ease-out');
```

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

addShader(id, shader)

Adds a shader to the layer's available shaders

Parameters:
Name Type Description
id string

Unique identifier for the shader
shader Shader

Shader instance to add
Inherited From:
Overrides:
Source:
Throws:

If shader with the same id already exists

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
const customShader = new OpenLIME.Shader({...});
layer.addShader('custom', customShader);
layer.setShader('custom');
```

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

boundingBox()

Gets layer bounding box in scene coordinates

Inherited From:
Overrides:
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Returns:

Bounding box

Type
BoundingBox

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

derive( [options])

Creates a new Layer that shares tiles with this layer but uses a different shader. This method allows efficient creation of derivative layers that share the same source textures, which is useful for applying different visual effects to the same image data without duplicating resources.

Parameters:
Name Type Argument Default Description
options Object <optional>
 {}

Options for the new layer

Properties
Name Type Argument Description
shaders Object <optional>

Map of shaders for the new layer
defaultShader string <optional>

ID of shader to set as active
label string <optional>

Label for the new layer (defaults to original label)
zindex number <optional>

Z-index for the new layer (defaults to original + 1)
visible boolean <optional>

Layer visibility (defaults to same as original)
transform Transform <optional>

Custom transform (defaults to copy of original)
mipmapBias number <optional>

Custom mipmap bias (defaults to original value)
pixelSize number <optional>

Custom pixel size (defaults to original value)
debug boolean <optional>

Debug mode flag (defaults to original value)
Inherited From:
Overrides:
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Returns:

A new layer sharing textures with this one

Type
Layer
Example
```javascript
// Create a derived layer with edge detection shader
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = originalLayer.derive({
    label: 'Edge Detection',
    shaders: { 'edge': enhancedShader },
    defaultShader: 'edge',
    zindex: 10
});
viewer.addLayer('edges', derivedLayer);
```
or
```javascript
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = layer.derive({
    label: 'Enhanced Image'
});
derivedLayer.addShader('enhanced', enhancedShader);
derivedLayer.setShader('enhanced');
viewer.addLayer('Enhanced Image', derivedLayer);
```

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:
Source:

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>

getPixelValues(x, y)

Gets pixel values for a specific pixel location Works with both single images and tiled formats

Parameters:
Name Type Description
x number

X coordinate in image space (0,0 at top-left)
y number

Y coordinate in image space (0,0 at top-left)
Inherited From:
Overrides:
Source:
Returns:

Array containing RGBA values for each raster at the specified pixel

Type
Array.<Uint8Array>

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

<async> loadTile(tile, callback)

Loads and processes a single image tile with optimized resource management. Implements request batching, concurrent loading, and proper error handling.

Parameters:
Name Type Description
tile Object

Tile specification object

Properties
Name Type Argument Description
index string

Unique tile identifier
url string

Base URL for tile resource
start number <optional>

Start byte for partial content (for tarzoom)
end number <optional>

End byte for partial content (for tarzoom)
offsets Array.<Object> <optional>

Byte offsets for interleaved formats
callback function

Completion callback(error, size)
Inherited From:
Overrides:
Source:
Throws:

If tile is already in processing queue

Type
Error
Returns:
Type
Promise.<void>

pixelSizePerMM()

Gets pixel size in millimeters

Inherited From:
Overrides:
Source:
Returns:

Size of one pixel in mm

Type
number

removeShader(id)

Removes a shader from the layer's available shaders

Parameters:
Name Type Description
id string

Identifier of the shader to remove
Inherited From:
Overrides:
Source:
Throws:

If shader with the specified id doesn't exist

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
// Remove a shader that's no longer needed
layer.removeShader('oldEffect');
```

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

scale()

Gets layer scale

Inherited From:
Overrides:
Source:
Returns:

Current scale value

Type
number

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:
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Fires:

setLight(light [, dt] [, easing])

Sets the light direction with optional animation

Parameters:
Name Type Argument Default Description
light Array.<number>

2D vector [x, y] representing light direction
dt number <optional>

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

Animation easing function
Source:

setMode(mode)

Sets shader visualization mode

Parameters:
Name Type Description
mode string

Mode to set
Inherited From:
Overrides:
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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
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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:

<static> projectToFlattenedSphere(p)

Projects a 2D point onto a flattened sphere using SGI trackball algorithm. This provides more intuitive light control by avoiding acceleration near edges. Based on SIGGRAPH 1988 paper on SGI trackball implementation.

Parameters:
Name Type Description
p Array.<number>

2D point [x, y] in range [-1, 1]
Source:
Returns:

3D normalized vector [x, y, z] on flattened sphere

Type
Array.<number>

<static> projectToSphere(p)

Projects a 2D point onto a sphere surface Used for converting 2D mouse/touch input to 3D light direction

Parameters:
Name Type Description
p Array.<number>

2D point [x, y] in range [-1, 1]
Source:
Returns:

3D normalized vector [x, y, z] on sphere surface

Type
Array.<number>

Events

ready

The event is fired when a layer is initialized.

Inherited From:
Overrides:
Source:

update

The event is fired if a redraw is needed.

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