JXG.Turtle

Class

This is the Turtle class. Constructs a new Turtle object. It is derived from JXG.GeometryElement. It stores all properties required to move a turtle.

Methods

Own

X

Y

Z

back

bk

clean

clearScreen

copyAttr

cs

evalAt

fd

forward

getHighlightPenColor

getPenAttribute

getPenColor

getPenSize

hasPoint

hideTurtle

home

ht

init

left

lookTo

lt

maxX

minX

moveTo

pd

penDown

penUp

pop

popTurtle

pu

push

pushTurtle

right

rt

setAttribute

setHighlightPenColor

setPenColor

setPenSize

setPos

showTurtle

st

X(t) → {Number}

if t is not supplied the x-coordinate of the turtle is returned. Otherwise the x-coordinate of the turtle curve at position t is returned.

Parameters

Name Type Description
t Number

parameter

Returns

x-coordinate of the turtle position or x-coordinate of turtle at position t

Type
Number

Details

Source
base/turtle.js, line 841

Y(t) → {Number}

if t is not supplied the y-coordinate of the turtle is returned. Otherwise the y-coordinate of the turtle curve at position t is returned.

Parameters

Name Type Description
t Number

parameter

Returns

x-coordinate of the turtle position or x-coordinate of turtle at position t

Type
Number

Details

Source
base/turtle.js, line 855

Z() → {Number}

Returns

z-coordinate of the turtle position

Type
Number

Details

Source
base/turtle.js, line 865

back(len) → {JXG.Turtle}

Move the turtle backwards.

Parameters

Name Type Description
len Number

of backwards move in user coordinates

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 330

bk()

Alias for JXG.Turtle#back

Details

Source
base/turtle.js, line 748

clean() → {JXG.Turtle}

Removes the turtle curve from the board. The turtle stays in its position.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 394

clearScreen() → {JXG.Turtle}

Removes the turtle completely and resets it to its initial position and direction.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 420

(private) copyAttr(key, val) → {Object}

Set a future attribute of the turtle.

Parameters

Name Type Description
key String
val Number | String

Returns

pointer to the attributes object

Type
Object

Details

Source
base/turtle.js, line 602

cs()

Alias for JXG.Turtle#clearScreen

Details

Source
base/turtle.js, line 790

evalAt(t) → {Number}

The "co"-coordinate of the turtle curve at position t is returned.

Parameters

Name Type Description
t Number

parameter
co. String

Either 'X' or 'Y'.

Returns

x-coordinate of the turtle position or x-coordinate of turtle at position t

Type
Number

Details

Source
base/turtle.js, line 813

fd()

Alias for JXG.Turtle#forward

Details

Source
base/turtle.js, line 742

forward(len) → {JXG.Turtle}

Move the turtle forward.

Parameters

Name Type Description
len Number

of forward move in user coordinates

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 285

getHighlightPenColor()

Get most recently set turtle color.

Returns

String RGB highlight color value of the last turtle segment.

Details

Source
base/turtle.js, line 545

(private) getPenAttribute(key)

Get attribute of the last turtle curve object.

Parameters

Name Type Description
key String

Returns

attribute value

Details

Source
base/turtle.js, line 514

getPenColor()

Get most recently set turtle color.

Returns

String RGB color value of the last turtle segment.

Details

Source
base/turtle.js, line 537

getPenSize()

Get most recently set turtle size (in pixel).

Returns

Number Size of the last turtle segment in pixel.

Details

Source
base/turtle.js, line 529

hasPoint(x, y) → {Boolean}

Checks whether (x,y) is near the curve.

Parameters

Name Type Description
x Number

Coordinate in x direction, screen coordinates.
y Number

Coordinate in y direction, screen coordinates.

Returns

True if (x,y) is near the curve, False otherwise.

Type
Boolean

Details

Source
base/turtle.js, line 901

hideTurtle() → {JXG.Turtle}

Sets the visibility of the turtle head to false,

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 625

home() → {JXG.Turtle}

Moves the turtle to position [0,0].

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 638

ht()

Alias for JXG.Turtle#hideTurtle

Details

Source
base/turtle.js, line 778

(private) init()

Initialize a new turtle or reinitialize a turtle after JXG.Turtle#clearScreen.

Details

Source
base/turtle.js, line 228

left(angle) → {JXG.Turtle}

Rotate the turtle direction to the right.

Parameters

Name Type Description
angle Number

of the rotation in degrees

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 361

lookTo(target) → {JXG.Turtle}

Rotates the turtle into a new direction. There are two possibilities:

Parameters

Name Type Description
target Number | Array

If a number is given, it is interpreted as the new direction to look to; If an array consisting of two Numbers is given targeted is used as a pair coordinates.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 677

lt()

Alias for JXG.Turtle#left

Details

Source
base/turtle.js, line 754

maxX()

Gives the upper bound of the parameter if the turtle is treated as parametric curve. May be overwritten in @see generateTerm.

Details

Source
base/turtle.js, line 880

minX()

Gives the lower bound of the parameter if the turtle is treated as parametric curve.

Details

Source
base/turtle.js, line 872

moveTo(target) → {JXG.Turtle}

Moves the turtle to a given coordinate pair. The direction is not changed.

Parameters

Name Type Description
target Array

Coordinates of the point where the turtle looks to.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 701

pd()

Alias for JXG.Turtle#penDown

Details

Source
base/turtle.js, line 772

penDown() → {JXG.Turtle}

Pen down, continues visible drawing

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 378

penUp() → {JXG.Turtle}

Pen up, stops visible drawing

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 369

pop()

Alias for JXG.Turtle#popTurtle

Details

Source
base/turtle.js, line 802

popTurtle() → {JXG.Turtle}

Gets the last position of the turtle on the stack, sets the turtle to this position and removes this position from the stack.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 660

pu()

Alias for JXG.Turtle#penUp

Details

Source
base/turtle.js, line 766

push()

Alias for JXG.Turtle#pushTurtle

Details

Source
base/turtle.js, line 796

pushTurtle() → {JXG.Turtle}

Pushes the position of the turtle on the stack.

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 649

Rotate the turtle direction to the right

Parameters

Name Type Description
angle Number

of the rotation in degrees

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 339

rt()

Alias for JXG.Turtle#right

Details

Source
base/turtle.js, line 760

setAttribute(attributes) → {JXG.Turtle}

Sets attributes of the turtle, see also JXG.GeometryElement#setAttribute. Sets the property for all curves of the turtle in the past and in the future.

Parameters

Name Type Description
attributes Object

key:value pairs

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 572

setHighlightPenColor(color) → {JXG.Turtle}

Sets the highlight pen color. Equivalent to setAttribute({highlightStrokeColor:color}) but affects only the future turtle.

Parameters

Name Type Description
color String

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 555

setPenColor(color) → {JXG.Turtle}

Sets the pen color. Equivalent to setAttribute({strokeColor:color}) but affects only the future turtle.

Parameters

Name Type Description
color String

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 496

setPenSize(size) → {JXG.Turtle}

Sets the pen size. Equivalent to setAttribute({strokeWidth:size}) but affects only the future turtle.

Parameters

Name Type Description
size Number

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 479

setPos(x, y) → {JXG.Turtle}

Moves the turtle without drawing to a new position

Parameters

Name Type Description
x Number

new x- coordinate
y Number

new y- coordinate

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 442

showTurtle() → {JXG.Turtle}

Sets the visibility of the turtle head to true,

Returns

pointer to the turtle object

Type
JXG.Turtle

Details

Source
base/turtle.js, line 611

st()

Alias for JXG.Turtle#showTurtle

Details

Source
base/turtle.js, line 784

Inherited

none

Example

Creates a figure 8 animation

var board = JXG.JSXGraph.initBoard('jxgbox',{boundingbox: [-250, 250, 250, -250]});
var t = board.create('turtle',[0, 0], {strokeOpacity:0.5});
t.setPenSize(3);
t.right(90);
var alpha = 0;

var run = function() {
 t.forward(2);
 if (Math.floor(alpha / 360) % 2 === 0) {
  t.left(1);        // turn left by 1 degree
 } else {
  t.right(1);       // turn right by 1 degree
 }
 alpha += 1;

 if (alpha < 1440) {  // stop after two rounds
  setTimeout(run, 20);
 }
}

run();

Parameters

Name Type Description
board JXG.Board

The board the new turtle is drawn on.
parents Array

Start position and start direction of the turtle. Possible values are

[x, y, angle]
[[x, y], angle]
[x, y]
[[x, y]]
attributes Object

Attributes to change the visual properties of the turtle object All angles are in degrees.

Details

Source
base/turtle.js, line 118