## Introduction

vtkColorTransferFunction is a color mapping in RGB or HSV space that

uses piecewise hermite functions to allow interpolation that can be

piecewise constant, piecewise linear, or somewhere in-between

(a modified piecewise hermite function that squishes the function

according to a sharpness parameter). The function also allows for

the specification of the midpoint (the place where the function

reaches the average of the two bounding nodes) as a normalize distance

between nodes.

See the description of class vtkPiecewiseFunction for an explanation of

midpoint and sharpness.

## Usage

// create color transfer function |

## Methods

### addHSVPoint

Add a point defined in HSV

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

`h` |
Number | Yes | Defines the hue of the color (between 0 and 1). |

`s` |
Number | Yes | Defines the saturation of the color (between 0 and 1). |

`v` |
Number | Yes | Defines the value of the color (between 0 and 1). |

### addHSVPointLong

Add a point defined in HSV

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

`h` |
Number | Yes | Defines the hue of the color (between 0 and 1). |

`s` |
Number | Yes | Defines the saturation of the color (between 0 and 1). |

`v` |
Number | Yes | Defines the value of the color (between 0 and 1). |

`midpoint` |
Number | No | |

`sharpness` |
Number | No |

### addHSVSegment

Add a line defined in HSV

Argument | Type | Required | Description |
---|---|---|---|

`x1` |
Number | Yes | The index of the first point. |

`h1` |
Number | Yes | Defines the hue of the color of the first point (between 0 and 1). |

`s1` |
Number | Yes | Defines the saturation of the color of the first point (between 0 and 1). |

`v1` |
Number | Yes | Defines the value of the color of the first point (between 0 and 1). |

`x2` |
Number | Yes | The index of the second point. |

`h2` |
Number | Yes | Defines the hue of the colorof the second point (between 0 and 1). |

`s2` |
Number | Yes | Defines the saturation of the color of the second point (between 0 and 1). |

`v2` |
Number | Yes | Defines the value of the color of the second point (between 0 and 1). |

### addRGBPoint

Add a point defined in RGB

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

`r` |
Number | Yes | Defines the red component (between 0 and 1). |

`g` |
Number | Yes | Defines the green component (between 0 and 1). |

`b` |
Number | Yes | Defines the blue component (between 0 and 1). |

### addRGBPointLong

Add a point defined in RGB

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

`r` |
Number | Yes | Defines the red component (between 0 and 1). |

`g` |
Number | Yes | Defines the green component (between 0 and 1). |

`b` |
Number | Yes | Defines the blue component (between 0 and 1). |

`midpoint` |
Number | No | |

`sharpness` |
Number | No |

### addRGBSegment

Add a line defined in RGB

Argument | Type | Required | Description |
---|---|---|---|

`x1` |
Number | Yes | The index of the first point. |

`r1` |
Number | Yes | Defines the red component of the first point(between 0 and 1). |

`g1` |
Number | Yes | Defines the green component of the first point(between 0 and 1). |

`b1` |
Number | Yes | Defines the red component of the first point (between 0 and 1). |

`x2` |
Number | Yes | The index of the second point. |

`r2` |
Number | Yes | Defines the red component of the second point (between 0 and 1). |

`g2` |
Number | Yes | Defines the green component of the second point (between 0 and 1). |

`b2` |
Number | Yes | Defines the blue component of the second point (between 0 and 1). |

### adjustRange

Remove all points out of the new range, and make sure there is a point at

each end of that range.

Argument | Type | Required | Description |
---|---|---|---|

`range` |
Array. |
Yes |

### applyColorMap

Argument | Type | Required | Description |
---|---|---|---|

`colorMap` |
Yes |

### buildFunctionFromArray

Construct a color transfer function from a vtkDataArray.

The order of values depends on the number of components

of the array.

3 -> RGB

4 -> XRGB

5 -> RGBMS

6 -> XRGBMS

X represents the input value to a function

RGB represents the red, green, and blue value output

M represents the midpoint

S represents sharpness

Argument | Type | Required | Description |
---|---|---|---|

`array` |
vtkDataArray | Yes |

### buildFunctionFromTable

Construct a color transfer function from a table.

Argument | Type | Required | Description |
---|---|---|---|

`xStart` |
Number | Yes | The index of the first point. |

`xEnd` |
Number | Yes | The index of the first point. |

`size` |
Number | Yes | |

`table` |
Array. |
Yes |

### estimateMinNumberOfSamples

Estimates the minimum size of a table such that it would correctly sample this function.

Argument | Type | Required | Description |
---|---|---|---|

`x1` |
Number | Yes | |

`x2` |
Number | Yes |

### extend

Method use to decorate a given object (publicAPI+model) with vtkColorTransferFunction characteristics.

Argument | Type | Required | Description |
---|---|---|---|

`publicAPI` |
Yes | object on which methods will be bounds (public) | |

`model` |
Yes | object on which data structure will be bounds (protected) | |

`initialValues` |
object | No | (default: {}) |

### fillFromDataPointer

Defines the nodes from an array ptr with the layout [X1, R1, G1, B1, X2,

R2, G2, B2, …, Xn, Rn, Gn, Bn] where n is the number of nodes.

Argument | Type | Required | Description |
---|---|---|---|

`nb` |
Number | Yes | |

`ptr` |
Yes |

### findMinimumXDistance

Traverses the nodes to find the minimum distance.

### getBlueValue

Get the blue color evaluated at the specified location

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

### getColor

Get the RGB color evaluated at the specified location

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

`rgb` |
Array. |
Yes | The Array of the RGB color to fill. |

### getGreenValue

Get the green color evaluated at the specified location

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

### getIndexedColor

Get the color given an integer index.

Argument | Type | Required | Description |
---|---|---|---|

`idx` |
Number | Yes | The index of the point. |

`rgba` |
Array. |
Yes | An Array of the RGBA color. |

### getNodeValue

For the node specified by index, set/get the location (X), R, G, and B

values, midpoint, and sharpness values at the node.

Argument | Type | Required | Description |
---|---|---|---|

`index` |
Number | Yes | |

`val` |
Array. |
Yes |

### getNumberOfAvailableColors

Get the number of available colors for mapping to.

### getRedValue

Get the red color evaluated at the specified location

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

### getSize

Get the number of points which specify this function

### getTable

Get a table of RGB colors at regular intervals along the function

Argument | Type | Required | Description |
---|---|---|---|

`xStart` |
Number | Yes | The index of the first point. |

`xEnd` |
Number | Yes | The index of the second point. |

`size` |
Number | Yes | |

`table` |
Array. |
Yes |

### getUint8Table

Argument | Type | Required | Description |
---|---|---|---|

`xStart` |
Number | Yes | The index of the first point. |

`xEnd` |
Number | Yes | The index of the first point. |

`size` |
Number | Yes | |

`withAlpha` |
Boolean | Yes |

### mapData

Map a set of scalars through the lookup table.

Argument | Type | Required | Description |
---|---|---|---|

`input` |
Yes | ||

`output` |
Yes | ||

`outFormat` |
Yes | ||

`inputOffset` |
Yes |

### mapScalarsThroughTable

Argument | Type | Required | Description |
---|---|---|---|

`input` |
Yes | ||

`output` |
Yes | ||

`outFormat` |
Yes | ||

`inputOffset` |
Yes |

### mapValue

Get the RGBA color evaluated at the specified location

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

### movePoint

Moves point from oldX to newX.

It removed the point from oldX. If any point existed at newX, it will also be removed.

Argument | Type | Required | Description |
---|---|---|---|

`oldX` |
Number | Yes | The old index of the point. |

`newX` |
Number | Yes | The new index of the point. |

### newInstance

Method use to create a new instance of vtkColorTransferFunction

Argument | Type | Required | Description |
---|---|---|---|

`initialValues` |
object | No | for pre-setting some of its content |

### removeAllPoints

Remove all points

### removePoint

Remove a point

Argument | Type | Required | Description |
---|---|---|---|

`x` |
Number | Yes | The index of the point. |

### setNodeValue

For a specified index value, set the node parameters

Argument | Type | Required | Description |
---|---|---|---|

`index` |
Number | Yes | |

`val` |
Array. |
Yes |

### setNodes

Set nodes directly

Argument | Type | Required | Description |
---|---|---|---|

`nodes` |
Yes |

#### Returns

Type | Description |
---|---|

true if a change happen |

### sortAndUpdateRange

Sort the vector in increasing order, then fill in

the Range

#### Returns

Type | Description |
---|---|

true if a change happen |

### updateRange

#### Returns

Type | Description |
---|---|

true if a change happen |

# Source

/** |

import vtkColorMaps from 'vtk.js/Sources/Rendering/Core/ColorTransferFunction/ColorMaps.json'; |

[ |