Sampler 2D

Utility for sampling 2D float arrays in row major or column major order.

Use

import { Sampler2D } from '@gov.nasa.jpl.honeycomb/sampler-2d';

const data = new Float32Array( [
    0, 0, 1, 0,
    0, 1, 1, 1
] );

const sampler = new Sampler2D( data, 2, 2 );
const result = new Array();
sampler.sample( 0.5, 0.5, result ); // 0.5, 1
sampler.samplePixel( 0, 1, result ); // 0, 1

API

Sampler2D

Texture-like object with an API for sampling image data.

For simplicity image data should be thought about as 0 0 being the bottom left pixel of the image. Use xInvert or yInvert to flip the image if necessary. Data is assumed to be interleaved.

channels

channels : Number

Return the number of channels in the image.

data

data : TypedArray

The image data.

stride

stride : Number = 4

The stride of a single pixel vector in the array.

width

width : Number

The width of the data grid.

height

height : Number

The height of the data grid as derived from the data length, stride, and width.

rowMajor

rowMajor : Number = true

Whether the data should be sampled as row major (true) or column major (false).

invertX

invertX : Number = false

Whether the data should be inverted along X.

invertY

invertY : Number = false

Whether the data should be inverted along Y.

interpolate

interpolate : Number = true

If true, then the result of sampling is bilinearly interpolated between the adjacent pixels.

constructor

constructor( data : TypedArray, width : Number, stride : Number = 4 ) : void

samplePixelChannel

samplePixelChannel( x : Number, y : Number, channel : Number ) : Number | null

X is expected to be in the range [ 0, width ] and Y within [ 0, height ]. Sets target to the pixel value at the given pixel. Decimal values are not supported.

Returns null if the provided values are outside a valid range. Returns the sample value otherwise.

samplePixel

samplePixel( x : Number, y : Number, target : Array ) : Boolean

X is expected to be in the range [ 0, width ] and Y within [ 0, height ]. Sets target to the pixel value at the given pixel. Decimal values are not supported.

Returns false if the provided values are outside a valid range. Returns true otherwise.

sampleChannel

sampleChannel( u : Number, v : Number, channel : Number ) : Number | null

U and V are expected to be in the range [ 0, 1 ]. Reads and interpolates the pixels if interpolate is true.

Returns null if the provided values are outside a valid range. Returns the sample value otherwise.

sample

sample( u : Number, v : Number, target : Array ) : Boolean

U and V are expected to be in the range [ 0, 1 ]. Reads and interpolates the pixels if interpolate is true.

Returns false if the provided values are outside a valid range. Returns true otherwise.

generateMipMap

generateMipMap( target : Sampler2D = null ) : void

Creates a mip map of this Sampler2D. If the dimensions of this sampler are not a factor of two then weighted sampling over multiple pixels are used and a square mipmap is generated.

SpatialSampler2D

A sampler that contains members and functions for sampling with a 2D transform into the samplers texture space.

extends Sampler2D

inverseMatrix

inverseMatrix : Array<Number> = identity matrix

A 3x3 matrix that transforms from the given coordinate frame into the local [ 0, 1 ] texture space of the sampler for use in the spatial sample functions.

constructor

constructor( args : ...rest ) : void

spatialSampleChannel

spatialSampleChannel( x : Number, y : Number, channel : Number ) : Number | null

Transforms X and Y by inverseMatrix before sampling the texture using @Sampler2D#sampleChannel and returning the result.

spatialSample

spatialSample( x : Number, y : Number, target : Array ) : Boolean

Transforms X and Y by inverseMatrix before sampling the texture using @Sampler2D#sample and returning the result.

setMinMax

setMinMax( minX : Number, minY : Number, maxX : Number, maxY : Number ) : void

Sets inverseMatrix to transform from a span of min to max x and y into the span [ 0, 1 ].

BandSampler2D

A sampler that stores each channel as a separate sampler and samples data accordingly. Use this if image data is not provided as interleaved.

implements BandSampler2D

rowMajor

rowMajor : null

invertX

invertX : null

invertY

invertY : null

bands

bands : Array<Sampler2D> = []

Array of sampler 2d instances where each band corresponds to a different channel.

constructor

constructor( bands : Array<Sampler2D> = [] ) : void