# Triangles

Next pictures are related to the equilateral triangle: angles of the regular triangle (in SVG), extreme points of an equilateral triangle with rounded corners (in SVG) and the impossible object Reutersvärd triangle (in SVG).

# Angles of regular polygons

We can draw an equilateral triangle repeating FORWARD and RIGHT commands:

```REPEAT 3 [ FORWARD 100 RIGHT 120 ]
```

More automatization could create the series of regular polygons, also with angles and other annotation, see the gallery and attached LibreLogo source code of the Wikipedia illustration:

# Extreme points

Next triangle is the result of the SVG transition of a mathematical illustration (the original picture was in the Wikimedia Commons category Top 200 images that should use vector graphics by usage).
The program of the picture draws 1 inch width outline with rounded corners, and in a second turn, narrow arcs with the appropriate radius.

```HIDETURTLE
PICTURE “Extreme points.svg” [
FILLCOLOR “SKYBLUE” PENCOLOR “SKYBLUE”
PENSIZE 72 RIGHT 30
FORWARD 100 RIGHT 120 FORWARD 100 FILL
PENCOLOR “RED” PENSIZE 2
REPEAT 3 [
CIRCLE [70, 70, 9h, 1h, 3]
PENUP RIGHT 120 FORWARD 100 PENDOWN
]
]
```

Note: this illustration helped to find a rare SVG export problem, see the enlarged line end on the right picture and the LibreOffice bug report.

# Reutersvärd optical illusion

One of the best optical illusions, created by the Swedish artist, Oscar Reutersvärd at the age of 18, in 1934. The next program draws the left picture. To get the optical illusion, open the SVG file in LibreOffice Draw, and place two shapes (bottom sides of the first cube) to foreground manually (for example, by Ctrl-Shift-+).

```TO tile
LEFT 60
REPEAT 2 [
FORWARD 40 RIGHT 120 FORWARD 40 RIGHT 60
] FILL RIGHT 60
END

TO cube
colors = [“GOLD”, “TEAL”, “TOMATO”]
REPEAT 3 [
PENCOLOR colors[REPCOUNT-1]
FILLCOLOR colors[REPCOUNT-1]
tile
RIGHT 120
]
END

PICTURE “Reutersvärd triangle.svg” [
HIDETURTLE PENSIZE 0.1 RIGHT 30
REPEAT 3 [
REPEAT 3 [
PENUP FORWARD 60 PENDOWN
cube
]
RIGHT 120
]
]
```

Note: Using narrow outlines (instead of “invisible” PENCOLOR) limits the SVG rendering problems in low resolution.

# Flag of Europe

Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia joined the European Union on 1 May 2004. The picture of the week is related to the 10th anniversary (and the upcoming Europe Day), also because LibreLogo is a development of the Hungarian E-Governmental Free Software Competence Centre, too, a project that has been supported by the European Union.

The flag of the European Union was part of the Wikipedia, but its official variants, the blue (1), and black monochrome (2), moreover the white-bordered versions of the three printing variants (3, 4, 5) were created recently by LibreLogo. Flag of Europe bővebben…

# Workshop in Brazil

SENID 2014 (Digital Inclusion National Seminar) at Passo Fundo University, Brazil, organized also a 4-hour LibreLogo workshop, during the 3-day conference at end of the April. Gilvan Vilarim, lecturer of the workshop, reported that the event had 15 participants, including teachers and some students (one of them was deaf, and she used the assistance of a Libras interpreter – Libras is the Brazilian version of the sign language for deaf people). The participants found the workshop to be very interesting, and they planned to continue using LibreLogo. (Thanks to Gilvan for the pictures, too.)