# Simple turtle graphics

Simple turtle graphics
You are encouraged to solve this task according to the task description, using any language you may know.

The first turtle graphic discussed in Mindstorms: Children, Computers, and Powerful Ideas by Seymour Papert is a simple drawing of a house. It is a square with a triangle on top for the roof.

For a slightly more advanced audience, a more practical introduction to turtle graphics might be to draw a bar chart.

See image here: https://i.imgur.com/B7YbTbZ.png

• Create a function (or subroutine) that uses turtle graphics to draw a house of a specified size as described above. Optionally make it lovely by adding details such as, for example, doors and windows.
• Create a function (or subroutine) that takes a list (array, vector) of non-negative numbers and draws a bar chart from them, scaled to fit exactly in a square of a specified size. The enclosing square need not be drawn.
• Both functions should return the turtle to the location it was at and facing in the same direction as it was immediately before the function was executed.

## Action!

```INCLUDE "D2:TURTLE.ACT" ;from the Action! Tool Kit

PROC Rectangle(INT w,h)
BYTE i

FOR i=1 TO 2
DO
Forward(h)
Left(90)
Forward(w)
Left(90)
OD
RETURN

PROC Square(INT w)
Rectangle(w,w)
RETURN

PROC Triangle(INT w)
BYTE i

FOR i=1 TO 3
DO
Forward(w)
Right(120)
OD
RETURN

PROC House(INT w)
Left(90)
Square(w)
Triangle(w)
Right(90)
RETURN

INT FUNC GetMax(INT ARRAY a INT count)
INT i,max

max=0
FOR i=0 TO count-1
DO
IF a(i)>max THEN
max=a(i)
FI
OD
RETURN (max)

PROC BarChart(INT ARRAY a INT count,w)
INT max,st,i

IF count=0 THEN RETURN FI
max=GetMax(a,count)
st=w/count
Right(90)
FOR i=0 TO count-1
DO
Rectangle(a(i)*w/max,st)
Forward(st)
OD
Left(180)
Forward(w)
RETURN

PROC Main()
BYTE CH=\$02FC,COLOR1=\$02C5,COLOR2=\$02C6
INT ARRAY a=[50 33 200 130 50]

Graphics(8+16)
COLOR1=\$0C
COLOR2=\$02

Color=1
SetTurtle(150,110,90)
House(75)

Color=0
Right(90)
Forward(5)
Left(90)

Color=1
BarChart(a,5,100)
Right(90)
Forward(5)
Right(90)

DO UNTIL CH#\$FF OD
CH=\$FF
RETURN```
Output:

```with Ada.Text_IO; use Ada.Text_IO;

-- procedure main - begins program execution
procedure main is
type Sketch_Pad is array(1 .. 50, 1 .. 50) of Character;
thePen : Boolean := True; -- pen raised by default
ycorr, xcorr : Integer := 25;

-- specifications
function penPosition(thePen : in out Boolean) return String;
procedure initGrid(sketch : in out Sketch_Pad);
procedure commandMenu(thePen : in out Boolean; xcorr : in out Integer;
ycorr : in out Integer);
procedure showMenu(xcorr : in out Integer; ycorr : in out Integer;
thePen : in out Boolean; sketch : in Sketch_Pad);
procedure moveCursor(thePen : in Boolean; sketch : in out Sketch_Pad;
xcorr : in out Integer; ycorr : in out Integer;
ch : in Integer);

-- procedure initGrid - creates the sketchpad and initializes elements
procedure initGrid(sketch : in out Sketch_Pad) is
begin
sketch := (others => (others => ' '));
end initGrid;

procedure showMenu(xcorr : in out Integer; ycorr : in out Integer;
thePen : in out Boolean; sketch : in Sketch_Pad) is

choice : Integer := 0;
begin
while choice /= 4 loop
Set_Col(15);
Put("TURTLE GRAPHICS APPLICATION");
Set_Col(15);
Put("===========================");
New_Line(2);

Put_Line("Enter 1 to print the grid map");
Put_Line("Enter 3 to raise pen up / down");
Put_Line("Enter 4 to exit the application");
choice := integer'value(Get_Line);

exit when choice = 4;

case choice is
when 1 => showGrid(sketch);
when 2 => commandMenu(thePen, xcorr, ycorr);
when 3 => Put_Line("Pen is "
& penPosition(thePen));
when others => Put_Line("Invalid input");
end case;
end loop;

-- function penPosition - checks changes the state of whether the pen is
-- raised up or down. If value is True, pen is rasied up
function penPosition(thePen : in out Boolean) return String is
str1 : constant String := "raised UP";
str2 : constant String := "raised DOWN";
begin
if thePen = True then
thePen := False;
return str2;
else
thePen := True;
end if;

return str1;
end penPosition;

-- procedure command menu - provides a list of directions for the turtle
-- to move along the grid
procedure commandMenu(thePen : in out Boolean; xcorr : in out Integer;
ycorr : in  out Integer) is

choice : Integer := 0;
begin
while choice <= 0 or choice > 5 loop
Set_Col(15);
Set_Col(15);
Put("============");
New_Line(2);

Put_Line("To move North enter 1");
Put_Line("To move South enter 2");
Put_Line("To move East enter 3");
Put_Line("To move West enter 4");
choice := integer'value(Get_Line);

case choice is
when 1 => moveCursor(thePen, sketch, xcorr, ycorr, choice);
when 2 => moveCursor(thePen, sketch, xcorr, ycorr, choice);
when 3 => moveCursor(thePen, sketch, xcorr, ycorr, choice);
when 4 => moveCursor(thePen, sketch, xcorr, ycorr, choice);
when 5 => showMenu(xcorr, ycorr, thePen, sketch);
when others => Put_Line("Invalid choice");
end case;
end loop;

-- procedure moveCursor - moves the cursor around the board by taking the
-- x and y coordinates from the user. If the pen is down, a character is
-- printed at that location. If the pen is up, nothing is printed but the
-- cursor still moves to that position
procedure moveCursor(thePen : in Boolean; sketch : in out Sketch_Pad;
xcorr : in out Integer; ycorr : in out Integer;
ch : in Integer) is

begin
if thePen = True then -- pen up so move cursor but do not draw
case ch is
when 1 => xcorr := xcorr - 1; ycorr := ycorr;
sketch(xcorr, ycorr) := ' ';
when 2 => xcorr := xcorr + 1; ycorr := ycorr;
sketch(xcorr, ycorr) := ' ';
when 3 => xcorr := xcorr; ycorr := ycorr + 1;
sketch(xcorr, ycorr) := ' ';
when 4 => xcorr := xcorr; ycorr := ycorr - 1;
sketch(xcorr, ycorr) := ' ';
when others => Put("Unreachable Code");
end case;

else -- pen is down so move cursor and draw
case ch is
when 1 => xcorr := xcorr - 1; ycorr := ycorr;
sketch(xcorr, ycorr) := '#';
when 2 => xcorr := xcorr + 1; ycorr := ycorr;
sketch(xcorr, ycorr) := '#';
when 3 => xcorr := xcorr; ycorr := ycorr + 1;
sketch(xcorr, ycorr) := '#';
when 4 => xcorr := xcorr; ycorr := ycorr - 1;
sketch(xcorr, ycorr) := '#';
when others => Put("Unreachable Code");
end case;
end if;
end moveCursor;

-- procedure showGrid - prints the sketchpad showing the plotted moves
procedure showGrid(sketch : in Sketch_Pad) is
begin
New_Line;

for I in sketch'Range(1) loop
for J in sketch'Range(2) loop
Put(character'image(sketch(I,J)));
end loop;
New_Line;
end loop;
New_Line;
end showGrid;

begin
New_Line;

initGrid(sketch);

New_Line;
end main;
```

## J

Translation of: Logo

Prerequisites (requires a network connection or, for a non-networked system, significant technical savvy), and assumes user is running the a recent version of J's qtide (perhaps J 9.3):

```   ;install each cut 'gl2 gles github:zerowords/tgsjo'
```

Implementation (note that this is meant to be copied and pasted to a file which J will load, rather than being typed in line by line -- manual typing would work if no errors were made, but that would be a painstaking approach):

```load'zerowords/tgsjo'
rotR   0 0 _90
translate 0 0 _40
clearscreen ''
createTurtle 0 0 0

rectangle=: {{
2 repeats {{ 'width height'=. y
forward height
left 90
forward width
left 90 }} y
}}

square=: {{size=. y
rectangle size,size
}}

triangle=:{{
3 repeats {{size=. y
forward size
right 120}} y
}}

house=:{{size=. y
left 90
square size
triangle size
right 90
}}

barchart=: {{'lst size'=. y
if.#lst do.
scale=. size%>./lst
width=. size%#lst
right 90
for_j. lst do.
rectangle (j * scale),width
forward width
end.
back size
left 90
end.
}}

penColor Red
house 150
pen 0
right 90
forward 10
left 90
pen 1 [ penColor Blue
barchart 0.5 0.3333 2 1.3 0.5; 200
pen 0
left 90
forward 10
left 270
pen 1
```

Opens a window with the indicated content. House is red, barchart is blue.

Note that we have used the Logo naming convention, which means that the height of our barchart is the width parameter in rectangle (and, likewise, the width of each bar is the height parameter in rectangle)

## Julia

Translation of: Wren

Outputs a PNG file.

```using Luxor, Colors

function house(🐢, x, y, siz)
oldorientation = 🐢.orientation
xpos, ypos = 🐢.xpos, 🐢.ypos
# house wall
Reposition(🐢, x, y)
Rectangle(🐢, siz, siz)
# roof
Reposition(🐢, x - siz / 2, y -  siz / 2)
Turn(🐢, -60)
Forward(🐢, siz)
Turn(🐢, 120)
Forward(🐢, siz)
# turtle_demo
doorheight, doorwidth = siz / 2, siz / 4
Pencolor(🐢, 0, 0, 0)
Reposition(🐢, x, y + doorheight / 2)
Rectangle(🐢, doorwidth, doorheight)
# window
windowheight, windowwidth = siz /3, siz / 4
Reposition(🐢, x + siz / 4, y - siz / 4)
Rectangle(🐢, windowwidth, windowheight)
Reposition(🐢, x - siz / 4, y - siz / 4)
Rectangle(🐢, windowwidth, windowheight)
Orientation(🐢, oldorientation)
Reposition(🐢, xpos, ypos)
end

function barchart(🐢, data, x, y, siz)
oldorientation = 🐢.orientation
xpos, ypos = 🐢.xpos, 🐢.ypos
maxdata = maximum(data)
# scale to fit within a square with sides `siz` and draw bars of chart
barwidth = siz / length(data)
Pencolor(🐢, 1.0, 0.0, 0.5)
Reposition(🐢, x, y)
for n in data  # draw each bar in chart
barheight = n * siz / maxdata
Reposition(🐢, x, y - barheight / 2)
Rectangle(🐢, barwidth, barheight)
x += barwidth
end
Orientation(🐢, oldorientation)
Reposition(🐢, xpos, ypos)
end

function testturtle(width = 400, height = 600)
dra = Drawing(600, 400, "turtle_demo.png")
origin()
background("midnightblue")
🐢 = Turtle()
Pencolor(🐢, "cyan")
Penwidth(🐢, 1.5)
house(🐢, -width / 3, height / 7, width / 2)
barchart(🐢, [15, 10, 50, 35, 20], width / 8, height / 8, width / 2)
finish()
end

testturtle()
```

## Logo

Translation of: Quackery
```to rectangle :width :height
repeat 2 [
forward :height
left 90
forward :width
left 90 ]
end

to square :size
rectangle size size
end

to triangle :size
repeat 3 [
forward size
right 120 ]
end

to house :size
left 90
square size
triangle size
right 90
end

to max :lst
if equalp count lst 1 [ output first lst ]
make "x max butfirst lst
if x > first lst [ output x ]
output first lst
end

to barchart :lst :size
right 90
if emptyp lst [ stop ]
make "scale size / (max lst)
make "width size / count lst
foreach lst [
rectangle ? * scale width
forward width ]
back size
left 90
end

clearscreen hideturtle
house 150
penup
right 90 forward 10 left 90
pendown
barchart [ 0.5 0.33333 2 1.3 0.5 ] 200
left 90 back 10 right 90```
Output:

## Perl

Added octangle window to house attic.

```#!/usr/bin/perl

use strict; # https://rosettacode.org/wiki/Simple_turtle_graphics
use warnings;
use Tk;
use List::Util qw( max );

my \$c; # the canvas

# turtle routines

my \$pen = 1; # true for pendown,  false for penup
my @location = (0, 0); # upper left corner
my \$direction = 0; # 0 for East, increasing clockwise
my @stack;
my \$radian = 180 / atan2 0, -1;
sub dsin { sin \$_[0] / \$radian }
sub dcos { cos \$_[0] / \$radian }
sub save { push @stack, [ \$direction, @location ] }
sub restore { (\$direction, @location) = @{ pop @stack } }
sub turn { \$direction += shift }
sub right { turn shift }
sub left { turn -shift }
sub forward
{
my \$x = \$location[0] + \$_[0] * dcos \$direction;
my \$y = \$location[1] + \$_[0] * dsin \$direction;
\$pen and \$c->createLine( @location, \$x, \$y, -width => 3 );
@location = (\$x, \$y);
}
sub back { turn 180; forward shift; turn 180 }
sub penup { \$pen = 0 }
sub pendown { \$pen = 1 }
sub text { \$c->createText( @location, -text => shift ) }

# make window

my \$mw = MainWindow->new;
\$c = \$mw->Canvas(
-width => 900, -height => 900,
)->pack;
\$mw->Button(-text => 'Exit', -command => sub {\$mw->destroy},
)->pack(-fill => 'x');
\$mw->after(0, \&run);
MainLoop;
-M \$0 < 0 and exec \$0;

sub box
{
my (\$w, \$h) = @_;
for (1 .. 2)
{
forward \$w;
left 90;
forward \$h;
left 90;
}
}

sub house
{
my \$size = shift;
box \$size, \$size;
right 90;
for ( 1 .. 3 )
{
right 120;
forward \$size;
}
penup;
left 90;
forward \$size;
left 90;
save;
forward \$size * 1 / 4;
pendown;
box \$size / 4, \$size / 2;
penup;
forward \$size * 3 / 8;
left 90;
forward \$size / 4;
right 90;
pendown;
box \$size / 4, \$size / 4;
penup;
restore;
save;
forward \$size / 2;
left 90;
forward \$size + 40;
right 90;
pendown;
for (1 .. 8)
{
forward 15;
left 45;
forward 15;
}
restore;
penup;
}

sub graph
{
save;
my \$size = shift;
my \$width = \$size / @_;
my \$hscale = \$size / max @_;
for ( @_ )
{
box \$width, \$hscale * \$_;
save;
penup;
forward \$width / 2;
left 90;
forward 10;
text \$_;
pendown;
restore;
forward \$width;
}
restore;
}

sub run
{
penup;
forward 50;
right 90;
forward 400;
pendown;
house(300);
penup;
forward 400;
pendown;
graph( 400, 2,7,4,5,1,8,6 );
}
```

## Phix

Library: Phix/pGUI
Library: Phix/online

You can run this online here.
I factored out some common code for the 2D and 3D versions (or started to, distributed version contains some additional diag aids)

```-- demo\rosetta\turtle.e
include pGUI.e
global Ihandle canvas, dlg
global cdCanvas cdcanvas
global bool pen_down = false

global procedure pendown(atom colour=CD_BLACK)
pen_down = true
cdCanvasSetForeground(cdcanvas, colour)
end procedure

global procedure penup()
pen_down = false
end procedure
```
```--
-- demo\rosetta\Simple_turtle_graphics.exw
-- =======================================
--
with javascript_semantics
include turtle.e -- (common code for 2D and 3D versions)

atom x = 0,
y = 0,
direction = 0

procedure walk(atom distance)
//
// Move forward by distance pixels.
//
atom start_x = x,
start_y = y,
angle = direction*PI/180
x += distance*sin(angle)
y += distance*cos(angle)
if pen_down then
cdCanvasLine(cdcanvas,start_x,start_y,x,y)
end if
end procedure

procedure right(atom angle)
direction = remainder(direction+angle,360)
end procedure

procedure left(atom angle)
right(360-angle)
end procedure

procedure move(sequence s)
-- s is a list of angles (odd elements)
--        and distances (even elements)
for i=1 to length(s) do
if odd(i) then
right(s[i])
else
walk(s[i])
end if
end for
end procedure

procedure rectangle(atom width, height)
move({0,height,90,width,90,height,90,width,90})
end procedure

procedure draw_house(atom width, height)
//
// Draw a house at the current x,y
// direction must be 0 for house to be upright
--  left(10) -- (deliberately wonky works fine too)
//       -- (as long as you undo it at the end)
// house walls
rectangle(width, height)
// door (maybe some windows too would be nice...)
penup()
move({90,width/7,-90})
pendown(CD_BLUE)
rectangle(width/8,height/2.5)
penup()
move({-90,width/7,90})
// roof
walk(height)
pendown(CD_RED)
d = sqrt(width*width+height*height)/2
move({a,d,180-a*2,d})
penup()
move({90+a,width,-90,height,180})
--  right(10)
end procedure

procedure draw_barchart(sequence nums, atom w, h)
// draw a barchart occupying the middle 60% of w,h
// nums can contain +ve and/or -ve values.
--  right(10) -- (ditto)
integer n = length(nums)
atom mx = max(max(nums),0),
mn = min(min(nums),0),
r = mx-mn,                 -- range
zl = abs(mn)/r*h*0.6+h/5,  -- zero line
bw = w*0.6/n               -- bar width
move({90,w/5,-90,zl})
pendown()
for i=1 to n do
atom ni = nums[i]/r*h*0.6
if ni>0 then
rectangle(bw,ni)
else
pendown(CD_RED)
right(90)
rectangle(-ni,bw)
left(90)
pendown(CD_BLACK)
end if
move({90,bw,-90})
end for
penup()
move({180,zl,90,w/5+bw*n,90})
--  left(10)
end procedure

function redraw_cb(Ihandle /*ih*/)
integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE")
cdCanvasActivate(cdcanvas)
cdCanvasClear(cdcanvas)
atom w2 = width/2,
qw = width/4,
qh = height/4
penup()
move({0,qh,90,qw,-90})
pendown()

draw_house(qw,qh)   -- house in the left half

penup()

move({90,w2,-90})   -- barchart in the right half

draw_barchart({0.5, -4/3, 2, 1.3, 0.5},width/2,height)

-- sanity checks
if round(x)!=0 then ?9/0 end if
if round(y)!=0 then ?9/0 end if
if round(direction)!=0 then ?9/0 end if

cdCanvasFlush(cdcanvas)
return IUP_DEFAULT
end function

IupOpen()
canvas = IupCanvas(Icallback("redraw_cb"),"RASTERSIZE=600x400")
dlg = IupDialog(canvas,`TITLE="Simple turtle graphics"`)
IupMap(dlg)
cdcanvas = cdCreateCanvas(CD_IUP, canvas)
IupShow(dlg)
IupSetAttribute(canvas, "RASTERSIZE", NULL) -- release the minimum limitation
if platform()!=JS then
IupMainLoop()
IupClose()
end if
```

## Python

Translation of: Quackery
```from turtle import *

def rectangle(width, height):
for _ in range(2):
forward(height)
left(90)
forward(width)
left(90)

def square(size):
rectangle(size, size)

def triangle(size):
for _ in range(3):
forward(size)
right(120)

def house(size):
right(180)
square(size)
triangle(size)
right(180)

def barchart(lst, size):
scale = size/max(lst)
width = size/len(lst)
for i in lst:
rectangle(i*scale, width)
penup()
forward(width)
pendown()
penup()
back(size)
pendown()

clearscreen()
hideturtle()
house(150)
penup()
forward(10)
pendown()
barchart([0.5, (1/3), 2, 1.3, 0.5], 200)
penup()
back(10)
pendown()
```
Output:

## Quackery

```  [ \$ "turtleduck.qky" loadfile ] now!

rot witheach
[ do 2over 2over
v< if 2swap
2drop ] ]                 is largest   (       [ --> n/d )

[ 2 times
[ 2dup walk
-1 4 turn
2over walk
-1 4 turn ]
2drop 2drop ]                 is rectangle ( n/d n/d -->     )

[ 2dup rectangle ]              is square    (     n/d -->     )

[ 3 times
[ 2dup walk
1 3 turn ]
2drop ]                       is triangle  (    n/d  -->     )

[ 1 2 turn
2dup square triangle
1 2 turn ]                    is house     (     n/d -->     )

[ stack ]                       is bar.width (         --> s   )

[ stack ]                       is bar.scale (         --> s   )

[ join temp put
dup size n->v
temp share do v/ 1/v
join bar.width put
dup largest
temp share do v/
join bar.scale put
witheach
[ do
bar.scale share do v/
bar.width share do
rectangle
bar.width share do fly ]
temp take do -v fly
bar.width release
bar.scale release ]          is barchart  (   [ n/d -->     )

turtle
150 1 house
10 1 fly
' [ [ 1 2 ] [ 1 3 ] [ 2 1 ] [ 13 10 ] [ 1 2 ] ] 200 1 barchart
-10 1 fly```
Output:

## Wren

Library: DOME
Library: Wren-turtle
```import "dome" for Window
import "graphics" for Canvas, Color
import "./turtle" for Turtle

class Main {
construct new(width, height) {
Window.resize(width, height)
Canvas.resize(width, height)
Window.title = "Simple turtle graphics"
_w = width
_h = height
}

init() {
Canvas.cls(Color.white)
_t = Turtle.new()
drawHouse(_w/4)
barChart([15, 10, 50, 35, 20], _w/3)
}

drawHouse(size) {
// save initial turtle position and direction
var saveX = _t.x
var saveY = _t.y
var saveD = _t.dir

_t.pen.width = 2

// draw house
_t.drawRect(_w/4, _h/2, size, size)

// draw roof
_t.right(30)
_t.walk(size)
_t.right(120)
_t.walk(size)

// draw door
var doorWidth  = (size/4).floor
var doorHeight = (size/2).floor
_t.drawRect(_w/4 + doorWidth/2, _h/2 + doorHeight, doorWidth, doorHeight)

// draw window
var windWidth  = (size/3).floor
var windHeight = (size/4).floor
_t.drawRect(_w/4 + size/2, _h/2 + size/2, windWidth, windHeight)

// restore initial turtle position and direction
_t.x = saveX
_t.y = saveY
_t.dir = saveD
}

// nums assumed to be all non-negative
barChart(nums, size) {
// save intial turtle position and direction
var saveX = _t.x
var saveY = _t.y
var saveD = _t.dir

// find maximum
var max = 0
for (n in nums) if (n > max) max = n

// scale to fit within a square with sides 'size' and draw chart
var barWidth = (size / nums.count).floor
var startX = _w / 2 + 20
var startY = _h / 2
for (i in 0...nums.count) {
var barHeight = (nums[i] * size / max).round
_t.drawRect(startX, startY - barHeight, barWidth, barHeight)
startX = startX + barWidth
}

// restore intial turtle position and direction
_t.x = saveX
_t.y = saveY
_t.dir = saveD
}

update() {}

draw(alpha) {}
}

var Game = Main.new(600, 600)
```
Output:
```Similar to Quackery image except that the house has a door and a single window.
```

## Yabasic

Translation of: Python
```// Rosetta Code problem: http://rosettacode.org/wiki/Simple_turtle_graphics
// Adapted from Python to Yabasic by Galileo, 01/2022

import turtle

sub rectang(width, height)
local i

for i = 1 to 2
move(height)
turn(-90)
move(width)
turn(-90)
next
end sub

sub square(size)
rectang(size, size)
end sub

sub triang(size)
local i

for i = 1 to 3
move(size)
turn(120)
next
end sub

sub house(size)
turn(180)
square(size)
triang(size)
turn(180)
end sub

sub barchart(lst\$, size)
local t\$(1), t(1), n, m, i, scale, width

n = token(lst\$, t\$())
redim t(n)

for i = 1 to n
t(i) = val(t\$(i))
if t(i) > m m = t(i)
next

scale = size/m
width = size/n
for i = 1 to n
rectang(t(i)*scale, width)
pen(false)
move(width)
pen(true)
next
pen(false)
move(-size)
pen(true)
end sub

startTurtle()
color 255, 255, 255
turn(90)
house(150)
pen(false)
move(10)
pen(true)
barchart("0.5 0.333 2 1.3 0.5", 200)```