ColorTransferFunction

Source (.js)Source (.d.ts)

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
const ctfun = vtkColorTransferFunction.newInstance();
ctfun.addRGBPoint(200.0, 1.0, 1.0, 1.0);
ctfun.addRGBPoint(2000.0, 0.0, 0.0, 0.0);

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[Number]	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[Number]	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[Number]	Yes	The Array of the RGB color to fill.

getColorSpace

Get the color space of the color transfer function.

Returns

Type	Description
ColorSpace

getDataPointer

Returns the nodes stored in the function, as an array of { x, r, g, b, midpoint, sharpness } objects. This is intended as a read-only reference to internally stored nodes that should not be modified outside the vtkColorTransferFunction object: direct writes bypass sortAndUpdateRange() and modified(), so the nodes can end up unsorted, the cached range stale, and the change will not propagate through the pipeline.

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[Number]	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[Number]	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.

getScale

Get the scale of the color transfer function.

Returns

Type	Description
Scale

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[Number]	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.

setColorSpace

Set the color space of the color transfer function.

Argument	Type	Required	Description
colorSpace	ColorSpace	Yes

setNodeValue

For a specified index value, set the node parameters

Argument	Type	Required	Description
index	Number	Yes
val	Array[Number]	Yes

setNodes

Set nodes directly

Argument	Type	Required	Description
nodes		Yes

Returns

Type	Description
	true if a change happen

setScale

Set the scale of the color transfer function.

Argument	Type	Required	Description
scale	Scale	Yes

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