Logo guide/reference

This Logo guide/reference is adapted from Joshua Bell's Logo Interpreter. The Logo commands specific to VRMath2's 3D Logo are in purple color.

The section numbers are per the Berkeley Logo Reference Manual in Brian Harvey's Computer Science Logo Style volume 2: Advanced Techniques for ease of comparison.

Data Types
Data Structure Primitives
Communication
Arithmetic
Logical Operations
Graphics
6.1. Turtle Motion
6.2. Turtle Motion Queries
6.3. Turtle Control
6.4. Turtle Queries
6.5. Pen and Background Control
6.6. Pen Queries
6.9. Primitive Objects
6.10. Material Settings
6.11. Scale Settings and Queries
6.12. Texture Settings
6.13. Font Settings
6.14. Object Settings and Manipulation
6.15. Animation
6.16. Behaviour
6.17. 3D Space and Navigation Control
Workspace Management
Control Structures
Environment Management
9.1. Date and Time

1. Data Types

"word: Text string (terminated by whitespace)
:variable: Input definition/variable reference
[ word ... ]: List of words or lists, whitespace separated
{ word ... }
{ word ... }@origin: Array of words whitespace separated
( expression ): Parenthesis can be used to group expressions
procedure input ...: Call procedure with default number of inputs
( procedure input ... ): Call procedure with an arbitrary number of inputs

2. Data Structure Primitives

2.1 Constructors

word expr expr
(word expr ...): Concatenate two (or more) words into one word.
list thing1 thing2
(list thing1 thing2 ...): Create a new list from the inputs
array size
(array size origin): Create a new array. The default origin is 1.
listtoarray list
(listtoarray list origin): Create a new array populated by members of a list
arraytolist array: Create a new list populated by members of a array
sentence thing1 thing2
(sentence thing1 thing2 ...)
se thing1 thing2
(se thing1 thing2 ...): Create a new list from the inputs (if non-lists) or members of the inputs (if lists)
fput thing list
lput thing list: Outputs list, but with thing added as a new first/last item
combine thing1 thing2: If thing2 is a word, like word; otherwise, like fput
reverse list: Outputs a list with the items in reverse order
gensym: Outputs a unique string, e.g. G1, G2, etc.

2.2 Data Selectors

first list
last list: Outputs the first or last item from the list, respectively
butfirst list
bf list
butlast list
bl list: Outputs the list, except for the first/last item
firsts listoflists: Outputs a list of the first item of each sublist
butfirsts listoflists
bfs listoflists: Outputs a list of sublists without the first item
pick list: Outputs one item from a list, at random
item index thing: Outputs the indexth item of the list or array
setitem index array value: Sets the indexth item of the array to value
remove thing list: Outputs the list with any occurences of thing removed
remdup list: Outputs the list with duplicates removed

2.3 Data Mutators

push stackname thing
pop stackname: Push to/pop from a stack i.e. list variable, e.g. make "s [] then push "s 1. Stacks grow from the front.
queue stackname thing
dequeue stackname: Add/remove from a queue i.e. list variable, e.g. make "q [] then queue "q 1. Queues grow from the end

2.4 Predicates

Predicates return 1 (true) or 0 (false)

wordp thing
word? thing
listp thing
list? thing
arrayp thing
array? thing
numberp thing
number? thing: Test if thing is a word, list, array, or number respectively.
equalp expr expr
equal? expr expr
expr = expr
notequalp expr expr
notequal? expr expr
expr <> expr: Equality/inequality tests. Compares strings, numbers, or lists (equal if length and all members are equal).
emptyp expr
empty? expr: Test if thing is an empty list or empty string.
beforep thing1 thing2
before? thing1 thing2: Test string collation order.
memberp thing list
member? thing list: Test if thing is equal to any member of list.
substringp thing1 thing2
substring? thing1 thing2: Test if thing1 is a substring of thing2.

2.5 Queries

count thing: Outputs length of a list or number of characters in a string
ascii expr: Outputs ASCII (actually, Unicode) code point for first character of string
char expr: Outputs Unicode character at specified code point
uppercase expr
lowercase expr: Outputs string converted to upper/lowercase

3. Communication

3.1 Transmitters

print thing
pr thing
(print thing1 thing2 ...)
(pr thing1 thing2 ...): Print inputs to the console, separated by spaces, and followed by a newline. Square brackets are only put around sublists.
type thing
(type thing1 thing2 ...): Like print but with no trailing newline.
show thing
(show thing1 thing2 ...): Like print but with square brackets around list inputs.

3.2 Receivers

3.3 File Access

3.4 Console (Terminal) Access

cleartext
ct: Clear the console.

4. Arithmetic

4.1 Numeric Operations

Inputs are numbers or numeric expressions, output is a number.

sum expr expr
(sum expr ...)
expr + expr
difference expr expr
expr - expr
product expr expr
(product expr ...)
expr * expr
quotient expr expr
(quotient expr ...)
expr / expr
power expr expr
expr ^ expr: Add, subtract, multiply, divide, and raise-to-the-power-of respectively. A single input to quotient returns the reciprocal.
remainder expr expr
expr % expr
modulo expr expr: Outputs the remainder (modulus). For remainder and % the result has the same sign as the first input; for modulo the result has the same sign as a the second input.
minus expr
- expr: Unary minus sign must begin a top-level expression, follow an infix operator, or have a leading space and no trailing space.
abs num: Absolute value
int num
round num: Truncate or round a number, respectively.
sqrt expr
exp expr
log10 expr
ln expr: Square root, e to the power of, common logarithm, and natural logarithm, respectively.
arctan expr
(arctan x y)
sin expr
cos expr
tan expr: The usual trig functions. Angles are in degrees.
radarctan expr
(radarctan x y)
radsin expr
radcos expr
radtan expr: The usual trig functions. Angles are in radians.
iseq first last: Outputs a list with integers from first to last, inclusive
rseq first last count: Outputs a list of count numbers from first to last, inclusive

4.2 Numeric Predicates

greaterp expr expr
greater? expr expr
expr > expr
greaterequalp expr expr
greaterequal? expr expr
expr >= expr
lessp expr expr
less? expr expr
expr <= expr
lessequalp expr expr
lessequal? expr expr
expr <= expr: Greater than, greater than or equal to, less than, less than or equal to, respectively. Inputs are numbers or numeric expressions, output is 1 (true) or 0 (false).

4.3 Random Numbers

random expr: Outputs a random number from 0 through one less than expr
rerandom
(rerandom expr): Reseeds the random number generator, either to a fixed value or the specified seed.

4.4 Print Formatting

form expr width precision: Returns a formatted string with the result of a numeric expression with precision decimal places and padded on the left with spaces (if necessary) to be at least width characters long.

4.5 Bitwise Operations

bitand expr expr
(bitand expr ...)
bitor expr expr
(bitor expr ...)
bitxor expr expr
(bitxor expr ...)
bitnot expr: Bitwise and, or, exclusive-or, and not, respectively.
ashift expr bitcount: Arithmetic bit shift. If bitcount is negative, shifts to the right, preserving sign.
lshift expr bitcount: Logical bit shift. If bitcount is negative, shifts to the right, zero-filling.

5. Logical Operations

true: Outputs 1
false: Outputs 0
and expr expr
(and expr ...)
or expr expr
(or expr ...)
xor expr expr
(xor expr ...)
not expr: Logical "and", "or", "exclusive-or", and "not", respectively. Inputs are numbers or numeric expressions, output is 1 (true) or 0 (false).

Due to the 3D nature of VRMath2 Logo, the distance is measured by meter (default) or centimeter, instead of pixel. Bacause of the 3D space, there are some extra turning (change of direction) and moving (change of position) commands.

Change location or position

forward expr
fd expr: Move turtle forward expr meter
back expr
bk expr: Move turtle backward expr meter
east expr: Move turtle to east expr meter (towards +x)
west expr: Move turtle to west expr meter (towards -x)
north expr: Move turtle to north expr meter (towards -z)
south expr: Move turtle to south expr meter (towards +z)
up expr: Move turtle up expr meter (towards sky)
down expr
dn expr: Move turtle down expr meter (towards ground)
setpos [ expr expr expr ]
setxyz expr expr expr
setx expr
sety expr
setz expr: Move turtle to the specified coordinate
home: Moves the turtle to center (0, 0 , 0), heading north

Change direction or orientation

left expr
lt expr: Turn expr degrees to the left of the turtle
right expr
rt expr: Turn expr degrees to the right of the turtle
rollup expr
ru expr: Roll Up expr degrees (head up or tail down)
rolldown expr
rd expr: Roll Down expr degrees (head down or tail up)
tiltleft expr
tl expr: Tilt Left expr degrees (left side down or right side up)
tiltright expr
tr expr: Tilt Right expr degrees (right side down or left side up)
setheading [ expr expr expr expr ]
seth [ expr expr expr expr ]: Rotate the turtle to the specified heading or orientation
lookatpos [ expr expr expr ]
lookatxyz expr expr expr
toward [ expr expr expr ]
towards [ expr expr expr ]: Rotate the turtle towards the specified [ x y z ] coordinates

Jump series commands (during pendown, move turtle without leaving track)

jump: Indicate an end or a start or a new face during faces construction
jumpon
jon: Jump on will make subsequent movements as jump movements, meaning no tracks.
jumpoff
joff: Jump off will cancel jump on effect.
jumppos [ expr expr expr ]
jumpxyz expr expr expr
jumpx expr
jx expr
jumpy expr
jy expr
jumpz expr
jz expr: Move turtle to the specified coordinate
jumpforward expr
jf expr
jumpback expr
jb expr
jumpeast expr
je expr
jumpwest expr
jw expr
jumpnorth expr
jn expr
jumpsouth expr
js expr
jumpup expr
ju expr
jumpdown expr
jd expr
jumphome expr
jh expr: Move turtle for the specified distance expr

6.2 Turtle Motion Queries

pos
getpos
location
position: Outputs the current turtle position as [ x y z ]
xcor
getx: Outputs the current turtle's x position
ycor
gety: Outputs the current turtle's y position
zcor
getz: Outputs the current turtle's z position
ori
heading
getori
orientation
direction: Outputs the current turtle heading as [x y z radian]

6.3 Turtle and Window Control

6.4 Turtle and Window Queries

meter
metre: Set the unit of distance to meter (default).
centimeter
centimetre
cm: Set the unit of distance to centimeter.
setturtle expr
setavatar expr: Set expr as the turtle. expr is the object id.

showturtle
st: Show the turtle
hideturtle
ht: Hide the turtle
clean: Clear the drawing area
clearscreen
cs: Same as clean and home together

shownp
shown?: Outputs 1 if the turtle is shown, 0 if the turtle is hidden
distanceto [ expr expr expr ]
distancetoxyz expr expr expr: Outputs the distance from the turtle to the specified [ x y z ] or x y z
distancebetween [ expr expr expr ] [ expr expr expr ]
distancebtw [ expr expr expr ] [ expr expr expr ]: Outputs the distance between the two specified [ x y z ] coordinates
avatar
turtle: Outputs the current avatar id, or turtle, if current avatar in control

6.5 Pen and Background Control

point

line

face

Set turtle track mode to point, line or face

pendown

pd

Turtle starts leaving a track

penup

pu

Turtle stops leaving a track

nextcolor

nc

Rotate pen color to the next color in the pallete

nextcoloron

ncon

nextcoloroff

ncoff

Set auto next pen color on/off when the turtle moves

setbackground expr

setbg expr

Set background index expr as in the background chooser. Index 45 (setbg 45) will use the current pen color as a single background color in the 3D space

pencoloron

pcon

pencoloroff

pcoff

Set pen color on/off for the Face object. When pcoff, the faces created will use material settings (see 6.10)

setpcname logocolor

Set pen color using the 16 names below. E.g., setpcname "white

setpencolor expr expr expr

setcolor expr expr expr

setrgb expr expr expr

setpc expr expr expr

Set pen color in R G B. The 3-expr r/g/b values in between 0 to 1000.
The standard Logo colors in VRMath2 are:

0: black	1: navy	2: blue	3: aqua
4: teal	5: green	6: olive	7: lime
8: maroon	9: red	10: orange	11: yellow
12: purple	13: white	14: silver	15: gray

setg expr
setb expr: Set pen color's R G B component individually, expr is ranging from 0 to 1000.

6.6 Pen Queries

pd?
pendownp
pendown?: Outputs 1 if the pen is down, 0 otherwise
pu?
penupp
penup?: Outputs 1 if the pen is up, 0 otherwise
penmode
pm: Outputs 0: point, 1: line or 2: face mode.
getpc
pc
pencolor: Outputs the current pen color, as a string of R G B, each ranging from 0 to 1000.
color
getcolor: Outputs the current pen color, as a string of R G B, each ranging from 0 to 1. This is useful for Color Interpolator.

Note: in 3D models, the R G B of color are ranging from 0 to 1. In Logo, they are ranging from 0 to 1000 to suit younger programmers.

6.9 Primitive Objects

cube
box: Create a 1x1x1 (in meter or current scale) cube at the turtle's position and direction
cylinder
can: Create a cylinder with diameter 1 and height 1 (in meter or current scale)
cone: Create a cone with base diameter 1 and height 1 (in meter or current scale)
sphere
ball: Create a sphere with diameter 1 (in meter)
torus
donut: Create a torus
snout: Create a snout
dish: Create a dish
pyramid: Create a pyramid
rectangulartorus
rectorus: Create a rectangular torus
slopedcylinder
slopedcan: Create a slopped cylinder
nozzle: Create a nozzle
elevationgrid
elegrid: Create a random 10x10 elevation grid to the right and back of the turtle
extrusion: Create an extrusion with a sqaure as the crossSection and three spine locations
arc: Create a 2D arc
pie: Create a 2D pie
circle: Create a 2D circle
disk: Create a 2D disk
rectangle: Create a 2D rectangle
inline url
world url: Insert a world (x3d file) as an object
picture url: Insert an image file (.jpg .jpeg .gif .png)
video url: Insert a video file (.mp4 .ogv)
sound url enabled loop: Insert an audio file (.wav .mp3, oga). enabled (default: true) and loop (default: false) are to be true or false.
pointlight: Insert a point light
dirlight
directionallight: Insert a directional light
spotlight: Insert a spotlight
transform: Insert a transform object (coordinate container)
label text: Insert a label. E.g., label "hello or label [Hello world!]
viewpoint: Insert a viewpoint with current view

6.10 Material Settings

setdiffusecolor expr expr expr
setdc expr expr expr: Set diffuse color of the material. The three exprs are R G B ranging from 0 to 1000.
setemissivecolor expr expr expr
setec expr expr expr: Set emissive color of the material. The three exprs are R G B ranging from 0 to 1000.
setspecularcolor expr expr expr
setsc expr expr expr: Set specular color of the material. The three exprs are R G B ranging from 0 to 1000.
setambientintensity expr
setai expr: Set the ambient intensity of the material, ranging from 0 to 1000.
setshininess expr
setsh expr: Set the shininess of the material, ranging from 0 to 1000.
settransparency expr
settr expr: Set the transparency of the material, ranging from 0 to 1000.
setmaterial index_set index_item
setmat index_set index_item: Set the material from the pre-defined materials in Material Chooser. The first input index_set is the index of the material groups ranging from 0 to 15. The second input index_item is the item from the material set, and is ranging from 0 to 35.

6.11 Scale Settings and Queries

Change scale setting will only affect objects created after, not before.

setscale expr expr expr: Set scale factor in x y z.
setscalex expr
setsx expr
setscalewidth expr
setscalew expr: Set scale factor in x dimension.
setscaley expr
setsy expr
setscaleheight expr
setscaleh expr: Set scale factor in y dimension.
setscalez expr
setsz expr
setscaledepth expr
setscaled expr: Set scale factor in z dimension.
scale: Output scale factor of x y z dimensions.
scalex
sx
scalewidth: Output scale factor of x dimension.
scaley
sy
scaleheight: Output scale factor of y dimension.
scalez
sz
scaledepth: Output scale factor of z dimension.

6.12 Texture Settings

setimagetexture index_set index_item
setit index_set index_item: Set image texture from Texture Chooser. The first input index_set is the index of texture groups ranging from 0 to 10. The second input index_item is the index of texture item in the texture group. ranging from 0 to 35.
setiturl url: Set image texture's URL to the selected object.
setitrepeats true|false
setitrs true|false: Set the image texture's repeats attribute to true or false. This has effect when the image texture scale s is greater than 1.
setitrepeatt true|false
setitrt true|false: Set the image texture's repeatt attribute to true or false. This has effect when the image texture scale t is greater than 1.
setitscale expr expr
setitsc expr expr: Set the image texture's scale factors in both s and t. expr is ranging from 0.001 to 1000.
setitscales expr
setitss expr: Set the image texture's scale factor in s. expr is ranging from 0.001 to 1000.
setitscalet expr
setitst expr: Set the image texture's scale factor in t. expr is ranging from 0.001 to 1000.
setittranslation expr expr
setittr expr expr: Set the image texture's translation offsets in both s and t. expr is ranging from -1 to 1.
setittranslations expr
setitts expr: Set the image texture's translation offset in s. expr is ranging from -1 to 1.
setittranslationt expr
setittt expr: Set the image texture's translation offset in t. expr is ranging from -1 to 1.
setitrotation expr
setitrot expr: Set the image texture's rotation in expr degrees, ranging from -360 to 360.
removeimagetexture id
removeit id
rmimagetexture id
rmit id: Remove image texture of the object id

6.13 Font Settings

The following font settings are of X3D specification. However, most of them have not yet been implemented in X3DOM.

setlabeltext text
setlt text: Set the label text as text when a label object is selected.
setfontfamily index
setff index: Set the font family of label, as defined in the Font Editor in the Property Inspector. index is ranging from 0 to 11.
setfontjustify index
setfj index: Set the font justify of label, as defined in the Font Editor in the Property Inspector. index is ranging from 0 to 15.
setfontstyle index
setfs index: Set the font style of label, as defined in the Font Editor in the Property Inspector. index is ranging from 0 to 3.
setfonthorizontal true|false
setfh true|false: Set the font direction vertical or horizontal.
setfontlefttoright true|false
setfl true|false: Set the font direction from left to right or right to left.
setfonttoptobottom true|false
setft true|false: Set the font direction from top to bottom or bottom to top.
setfsize expr: Set font size of the label text, ranging from 0 to 100.
setfspacing expr: Set space between individual letter in the label text, ranging from 0 to 100.

6.14 Object Settings and Manipulation

object: Output the last created object's id or last selected object's id.
select id: Select object by id.
deselect: Deselect object.
hide id: Hide the object by id. Object hidden will not be rendered in 3D space.
unhide id: Unhide the object by id.
copy id: Copy the object id to paste later.
paste: Paste the copied object.
delete id: Delete the object by id
get id attr: Get is an universal command to retrieve any attribute's value of any object. The first input is the object's id, the second input is the attribute name attr. Get will output the value of the specified attribute.
set id attr value_list: Set is an universal command to change any attribute's value of any object. The first input is the object's id, the second input is the attribute name attr, the value_list is the value to the attribute. E.g., set "obj_0_cube "size [1 2 1]
move source_id destination_id: Move an object in or out of a transform object. The first input is the source object's id. The second input is the destination object's id. E.g., if obj_0 is a cube, obj_1 is a transform object, move "obj_0 "obj_1 will make obj_0 the child of obj_1.
setparent parent_id
sp parent_id: Set the parent transform node. Once set, any objects created after will be children of the parent transform node. The default parent transform node is root. Only a transform node can be set as a parent. For example,
SETPARENT "obj_0 ; make transform node obj_0 as parent.
SETPARENT "root ; objects created after this will be children of root.
parent: Output the curent parent transform id.

6.15 Animation

Animations are produced by TIMESENSOR, INTERPOLATOR and ROUTE as of X3D specification.

timesensor id cycleInterval loop: Create or set a timesensor with the first input as the timesensor id, the second input as the cycleInterval, and the third input as loop ("true or "false or true or false).
coordinateinterpolator id key_list keyValue_list
coorint id key_list keyValue_list: Create or set a coordinate interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [ [ [0 0 0] [0 1 0] [0 0 0] ] [ [0 0 0] [0 1 0] [0 0 0] ] [ [0 0 0] [0 1 0] [0 0 0] ] ]) in coordinates. This interpolator outputs a set of coordinates useful to animate shapes created by the turtle track.
normalinterpolator id key_list keyValue_list
norint id key_list keyValue_list: Create or set a normal interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [ [ [0 0 0] [0 1 0] [0 0 0] ] [ [0 0 0] [0 1 0] [0 0 0] ] [ [0 0 0] [0 1 0] [0 0 0] ] ]) in normalised vectors. This interpolator outputs a set of normalised vectors useful to render normalised surfaces.
positioninterpolator id key_list keyValue_list
posint id key_list keyValue_list: Create or set a position interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [ [0 0 0] [0 1 0] [0 0 0] ]) in positions. This interpolator output a single coordinate useful to animate position of object in 3D space.
orientationinterpolator id key_list keyValue_list
oriint id key_list keyValue_list: Create or set an orientation interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [ [0 1 0 0] [0 1 0 3.14] [0 1 0 6.28] ]) in orientations. This interpolator outputs a single orientation useful to animate rotation of object in 3D space.
colorinterpolator id key_list keyValue_list
colorint id key_list keyValue_list
clrint id key_list KeyValue_list: Create or set a color interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [ [1 0 0] [0 1 0] [0 0 1] ]) in colors. This interpolator outputs a single color useful to animate color of material (e.g., diffuseColor, emissiveColor, specularColor).
scalarinterpolator id key_list keyValue_list
scalarint id key_list keyValue_list
sclrint id key_list keyValue_list: Create or set a scalar interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [1 3 1]) in single values. This interpolator outputs a single number useful to animate a dimension of object (e.g., height, radius).
vectorinterpolator id key_list keyValue_list
vectorint id key_list keyValue_list
vecint id key_list keyValue_list: Create or set a vector interpolator with the first input as the id, the second input as the key (e.g., [0, 0.5, 1]), and the third input as the keyValue (e.g., [1 3 1 2 0 2 1 2 3] [0 1 2 1 2 3 2 1 2 ] [1 3 1 2 0 2 1 2 3]) in sets of single values. This interpolator outputs a set of single number useful to animate the height of ElevationGrid.
route id fromNode fromField toNode toField: Create or set a route with five inputs as id, fromNode, fromField, toNode, toField respectively.
removeroute id
rmroute id: Remove route with id as id.
spin id direction cycleInterval: Spin object with id as id, in one of the six axes directions as direction, with a loop cycleInterval. The direction is a Logo word and only in the twelve below:
right, rt, left, lt, tiltright, tr, tiltleft, tl, rollup, ru, rolldown, rd
The cycleInterval must be a non-zero positive number.
SPIN is a convenient command, which creates a timesensor, an orientationInterpolator, and two routes. For example:

CS BOX ; create a box with id obj_0
SPIN "obj_0 "right 10 ; spin the box in the right turn direction with a 10 second cycle

removespin id rmspin id: Remove the spin animation on object id.
travel id path cycleInterval: Make the object id travel along a path. The path is a Logo list containing at least two coordinates. The cycleInterval specify the cycle time in seconds to travel. For example:
CS BOX ; create a box with id obj_0
TRAVEL "obj_0 [ [0 0 0] [0 1 0] [0 0 0] ] 10 ; The box travels from (0,0,0) to (0,1,0) then back to (0,0,0) linearly with a 10 second cycle

removetravel id rmtravel id: Remove the travel animation on object id.
orient id directions cycleInterval: Make the object id orient with the given directions. The directions is a Logo list containing at least two directions. The cycleInterval specify the cycle time in seconds to orient. For example:
CS BOX ; create a box with id obj_0
ORIENT "obj_0 [ [0 0 1 0] [0 -1 0 1.5708 ] [0 0 1 0] ] 10 ; The box orients (rotates) from (0,0,1,0) to (0,-1,0,1.5708) (right 90) then back to (0,0,1,0) linearly with a 10 second cycle

removeorient id rmorient id: Remove the orient animation on object id.
tour id views cycleInterval: Make the viewpoint object id touring with the given views. The views is a Logo list containing at least two views collected using COLLECTVIEW command. if manual construct, a vew contains a position (x, y, z) and an orientation (x, y, z, r). The cycleInterval specifies the cycle time in seconds to tour. For example:
CS VIEWPOINT ; create a viewpoint with id as obj_0
TOUR "obj_0 [ [0 1 5 0 0 0 0] [0 0 1.1498 0 0 0 0 ] [0 1 5 0 0 0 0] ] 10 ; The viewpoint will tour through these three views in a 10-second cycle

removetour id rmtour id: Remove tour animation on the viewpoint id.
collectposition variableName
collectlocation variableName collectpos variableName: Start collecting positions of the turtle into variable variableName as a Logo word. After this command, every change of position of the turtle will be collected. You can start moving the turtle to collect a path of coordinates. To commit the collected coordinates into the variable, please use ENDCOLLECT variableName command. Positions collected can be used as the path for the TRAVEL command.
collectdirection variableName
collectorientation variableName collectori variableName: Start collecting orientations of the turtle into variable variableName as a Logo word. After this command, every change of direction of the turtle will be collected. You can start turning the turtle to collect a set of directions. To commit the collected directions into the variable, please use ENDCOLLECT variableName command. Orientations collected can be used as the directions for the ORIENT command.
collectview variableName: Collect current view into the variable variableName as a Logo word. A view is a 7-item list containing view position (x, y, z) and orientation (x, y, z, r). The use of this command is intended to be interactive instead of writen in a Logo program (although this is also possible in following mode). So to use this command, you firstly navigate in the 3D window to get a view you like, then specify this command with a variableName. After this, you will nagivate to a next view you like and specify exactly the same command and variableName again. You continue collecting views and at the end, use ENDCOLLECT variableName command to make it a Logo variable. The :variableName can later be used in the TOUR command to create a tour animation applying to a VIEWPOINT object.
endcollect variableName: End collection and set the variable variableName as a Logo word in Logo.

6.16 Behaviour

Behaviours are produced by Events and Actions. Events are behaviours trigged by input devices such as a mouse CLICK on an object. Actions are behaviours to be performed on certain Events. Actions have no effect until they are associated with Events. For example:

CS ; clearscreen
DIRLIGHT ; create a directional light (obj_0, and the actual light's id is obj_0_dirlight)
BALL ; create a sphere (obj_1)
TOGGLE "action1 "obj_0_dirlight "on   ; create a toggle action named action1, which toggles object's (obj_0_dirlight) attribute (on) between true and false.
CLICK "obj_1 "action1   ; associate action1 with obj_1's click event. So when the sphere is clicked, it toggles the directional light.

Events

click id action: Perform action when object id is clicked.
removeclick id
rmclick id: Remove click event on the object id.

Actions

update name id attr value: Create an update action named name, which updates the attribute attr of object id with value. value can be number, word or list.
toggle name id attr: Create a toggle action named name, which toggles the attribute attr of object id. The attr must be an attribute with values true or false.
playnote name instrument note
Create a playnote action named name, which plays the instrument instrument of note note. The instrument must be a number from 1 to 3 (1: Piano, 2: Acoustic Guitar, 3: Trumpet). The note must be a number from 1 to 88, or from A-1 to C7. Note number 40 is the same as C3 and 41 is the same as C#3.

goto name id
Create a goto action named name, which focuses the object with id as id in view. If the object is a viewpoint, then this action will goto the viewpoint.
rmaction name
removeaction name: Remove the action named name from the internal action registry. Note: this will not remove the effect once it has been associated with an event onto an object.

6.17 3D Space and Navigation Control

The following commands correspond to the functions in the toolbar in the 3D window.

examine: Change navigation mode to Examine.
walk: Change navigation mode to Walk.
fly: Change navigation mode to Fly.
turtleeye
te: Change navigation mode to TurtleEye (as looking through the turtle's eyes).
follow: Change navigation mode to Follow.
navmode: Return current navigation mode. 0: Examine, 1: Walk, 2: Fly, 3: TurtleEye, 4: Follow.
restoreview
rv: Restore original viewpoint.
showall
sa: Fit all objects into view in the 3D window.
showobject id
so id: Fit object id into view in the 3D window.
setrotationcenter x y z
setrc x y z: Set rotation center to the given coordinate x y z for Examine mode.
rotationcenter
rc
getrc: Return rotation center (x,y,z) of the Examine mode.
headlighton
hlon: Turn on headlight.
headlightoff
hloff: Turn off headlight.
headlight
hl?: Return current headlight status. 0: off, 1: on.
getview: Return current view as a 7-item list. The first 3 items are the view position, and the last 4 items are the view orientation.
getviewpos: Return current view position [x, y, z] as a list. These are the first 3 items of GETVIEW.
getviewori: Return current view orientation quaternion [x, y, z, r] as a list. These are the last 3 items of GETVIEW.

7. Workspace Management

7.1 Procedure Definition

to procname inputs ... statements ... end: Define a new named procedure with optional inputs
def procname: Outputs the definition of a named procedure as a string
copydef newname oldname: Copy a procedure. If a procedure newname already existed it will be overridden. Primitive procedures can't be overridden unless REDEFP is TRUE.

7.2 Variable Definition

make varname expr: Update a variable or define a new global variable. The variable name must be quoted, e.g. make "foo 5
name expr varname: Like make but with the inputs reversed
local varname
(local varname ...): A subsequent make will create the variable(s) in the local scope instead of the global scope
localmake varname expr: Define a variable in the local scope (shortcut for local then make
thing varname: Outputs the value of variable. :foo is a shortcut for thing "foo
global varname: Reserve the variable at the global scope. This doesn't do anything useful.

7.3 Property Lists

pprop plistname propname value: Set the property propname in the property list plistname to value value.
gprop plistname propname: Get the value of the property propname in the property list plistname, or the empty list if no such property.
remprop plistname propname: Remove the property propname in the property list plistname.
plist plistname: Return a list of properties in the property list plistname, alternating property name, property value.

7.4 Workspace Predicates

Predicates return 1 (true) or 0 (false)

procedurep name
procedure? name: Test if there is a procedure with the given name.
primitivep name
primitive? name: Test if there is a built-in procedure with the given name.
definedp name
defined? name: Test if there is a user-defined procedure with the given name.
namep name
name? name: Test if there is a variable with the given name.
plistp name
plist? name: Test if there is a property list with the given name.

7.5 Workspace Queries

contents: Outputs a list with three members. The first is a list of user-defined procedure names. The second is a list of defined variables. The third is a list of non-empty property list names. Only non-buried procedures, variables, and property lists are included.
buried: Outputs a list with three members. The first is a list of user-defined procedure names The second is a list of defined variables. The third is a list of non-empty property list names. Only buried procedures, variables, and property lists are included.
procedures: Outputs a list of user-defined non-buried procedure names.
primitives: Outputs a list of primitive non-buried procedure names.
globals: Outputs a list of defined non-buried global variables.
names: Outputs a list with two members. The first is an empty list. The second is a list of defined non-buried variables.
plists: Outputs a list with three members. The first is an empty list. The second is an empty list. The third is a list of non-empty non-buried property list names.
namelist name
namelist namelist: Return a contents-style list with the given variable names.
pllist plname
pllist plnamelist: Return a contents-style list with the given property lists.

7.7 Workspace Control

reset: Reset scale, material, texture, distance unit to default value.
erase contentslist: Takes a three member list, where the first is a list of user-defined procedure names to erase, the second is a list of defined variables to erase, the third is a list of property lists to erase. Primitive procedures can't be erased unless REDEFPis TRUE.
erall: Erase all non-buried user-defined procedures, variables and property lists.
erps: Erase all non-buried user-defined procedures.
erns: Erase all non-buried variables.
erpls: Erase all non-buried property lists.
ern varname
ern varnamelist: Erase the named variable(s).
epl plname
epl plnamelist: Erase the named property list(s).
bury contentslist: Takes a three member list, where the first is a list of user-defined procedure names to bury, the second is a list of defined variables to bury, the third is a list of property lists to bury.
buryall: Bury all user-defined procedures, variables, and property lists.
unbury contentslist: Takes a three member list, where the first is a list of user-defined procedure names to unbury, the second is a list of defined variables to unbury, the third is a list of property lists to unbury.
unburyall: Unbury all user-defined procedures, variables, and property lists.
buriedp contentslist
buried? contentslist: Return 1 if the first named user-defined procedure, variable, or property list exists and is buried, 0 otherwise.

8. Control Structures

8.1 Control

run [ statements ... ]: Run the specified statements once
runresult [ statements ... ]: Run the specified statements once. If the statements return a value, the result is a list with the value as a single member. Otherwise, the result is an empty list.
repeat expr [ statements ... ]: Repeat statements expr times
forever [ statements ... ]: Repeat statements forever. Used inside a user-defined procedure that terminates with output or stop
repcount: Outputs the current iteration number of the current repeat or forever
if expr [ statements ... ]: Execute statements if the expression is non-zero
ifelse expr [ statements ... ] [ statements ... ]: Execute first set of statements if the expression is non-zero, otherwise execute the second set
test expr: Test the specified expression, save the result in the local scope for subsequent use by iftrue or iffalse
iftrue [ statements ...]
ift [ statements ...]
iffalse [ statements ...]
iff [ statements ...]: Run the statements if the result of the last local test was non-zero (true) or zero (false) respectively.
stop: End the running procedure with no output value
output expr
op expr: End the running procedure and output the specified value
wait time
Pauses execution. time is in 60ths of a second.
bye: Terminate the program
.maybeoutput expr: Like output if expr returns a value, like stop otherwise
ignore expr: Evaluate and ignore results of the expression
for controllist [ statements ...]: Typical for loop. The controllist specifies three or four members: the local varname, start value, limit value, and optional step size.
do.while [ statements ...] expr: Runs the specified statements at least once, and repeats while the expression is non-zero (true).
while expr [ statements ...]: Runs the specified statements only while the expression remains non-zero (true).
do.until [ statements ...] expr: Runs the specified statements at least once, and repeats while the expression is zero (false).
until expr [ statements ...]: Runs the specified statements only while the expression remains zero (false).
case value [ clauses ... ]: For each clause in order: If the clause is of the form [ ELSE expr ] then expr is evaluated and returned. Otherwise, if the clause is of the form [ [ matches ] expr ] and value is a member of matches then expr is evaluated and returned.
cond [ clauses ... ]: For each clause in order: If the clause is of the form [ ELSE expr ] then expr is evaluated and returned. Otherwise, if the clause is of the form [ [ expr1 ] expr2 ] and expr1 evaluates to non-zero (true) then expr2 is evaluated and returned.

8.2 Template-based Iteration

These higher-level procedures support only the named procedure form of template. The first input is the name of a procedure to call.

apply procname list: Call procname with the members of list as inputs
invoke procname input1
(invoke procname input1 ...): Call procname with the specified inputs as inputs
foreach procname list: call procname for each item in the list
map procname list: Outputs a list composed of the results of calling procname for each item in the list
filter procname list: Outputs a list composed of the input list where procname called on the item returns non-zero (true)
find procname list: Outputs the first item in list for which calling procname on it returns non-zero (true). If not found, the empty list is returned.
reduce procname list
(reduce procname list initial): Call procname repeatedly with two inputs - the current value and the next list item. If initial is not specified, the first list element is used instead.

9. Environment Management

9.1 Date and Time

getdate: Returns the day of the month (from 1-31)
getday: Returns the day of the week (from 0-6)
getyear
getfullyear: Returns the year (four digits)
gethours: Returns the hour (from 0-23)
getmilliseconds: Returns the milliseconds (from 0-999)
getminutes: Returns the minutes (from 0-59)
getmonth: Returns the month (from 0-11)
getseconds: Returns the seconds (from 0-59)
gettime: Returns the number of milliseconds since midnight Jan 1, 1970
getdatestring: Converts the date portion of a Date object into a readable string. E.g., Sat Feb 15 2014
gettimestring: Converts the time portion of a Date object to a string. E.g., 14:29:32 GMT+1000 (EST)

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