# Context Free Art – Tutorial 4

The following examples illustrate the use of repetition in Context Free Art.

```startshape MyShape

path Line1 {
MOVETO {x 0 y 0}
LINETO {x 1 y 0}
STROKE {width .01}
}

rule MyShape {
36 * {r 10} Line1 {}
}
```
```startshape MyShape

path Line1 {
MOVETO {x 0 y 0}
LINETO {x 1 y 0}
STROKE {width .01}
}

rule MyShape {
36 * {r 10 x 0.03} Line1 {}
}
```

# Context Free Art – Tutorial 3

These exercises cover the use of path in a shape.

```startshape MyShape

path Line1 {
MOVETO {x 0 y 0}
LINETO {x 1 y 1}
STROKE {width .01}
}

rule MyShape {
Line1 {}
}
```
```startshape MyShape

path Line1 {
MOVETO {x 0 y 0}
LINETO {x 1 y 1}
LINETO {x 0 y 1}
LINETO {x 1 y 0}
LINETO {x 0 y 0}
STROKE {width .01}
}

rule MyShape {
Line1 {}
}
```
```startshape MyShape

path Line1 {
MOVETO {x 0 y 0}
LINETO {x 1 y 0}
STROKE {width .01}
}

rule MyShape {
Line1 {r 25}
}
```

# Context Free Art – Tutorial 2

We introduce the use of the rotation parameter for a shape:

```startshape MyShape

rule MyShape {
SQUARE {x -4 r 90}
SQUARE {x -2 r 70}
SQUARE {r 50}
SQUARE {x +2 r 30}
SQUARE {x +4 r 10}
}```

```
Rotation

```

# Context Free Art – Tutorial 1

After we can create different primitive shapes, we start to combine them together. We cannot simply put all the primitive shapes within one single shape rule, like:

```startshape MyShape

rule MyShape {
CIRCLE {}
TRIANGLE {}
SQUARE {}
}```

Every shape command comes with parameters. We work with the translation parameters x and y to move the shape around in the canvas.

```startshape MyShape

rule MyShape {
CIRCLE {x -2}
TRIANGLE {}
SQUARE {x 2}
}```
```
Multiple shapes```
```startshape MyShape

rule MyShape {
CIRCLE {y 2}
TRIANGLE {}
SQUARE {y -2}
}```

```startshape MyShape

rule MyShape {
CIRCLE {x 2 y 2 size 0.8}
TRIANGLE {size 2}
SQUARE {x -2 y -2 size 0.5}
}```

```
Size variation```

# Context Free Art

To prepare for a new course Evolutionary Graphics in AVA, I am testing the use of various graphical tools. One of them is the Context Free Art. It is a ruled based language to generate complex imagery. It cannot be described as a programming language as it lacks a lot of procedural elements. Its recursive capability makes it a good choice for generative type of graphics.

The Community of Variation book contains the sample of drawings in the gallery.

The drawing is done by typing a sequence of rules on the left hand panel. Press the ‘Render’ button to generate the graphics.

Every ‘program’ starts with a startshape keyword. For example, to draw a circle, we can type in the following:

```startshape MyShape

rule MyShape {
CIRCLE {}
}```

```
Circle```

To draw a square, type:

```startshape MyShape

rule MyShape {
SQUARE {}
}```

```
Square```

To draw a triangle, type:

```startshape MyShape

rule MyShape {
TRIANGLE {}
}```

```
Triangle```