Take a look of this example and see how it can be done with FILL command and the colour adjustments.

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 {}
}

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}
}

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}
}

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}
}

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}
}

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 {}
}

To draw a square, type:

startshape MyShape

rule MyShape {
     SQUARE {}
}

To draw a triangle, type:

startshape MyShape

rule MyShape {
     TRIANGLE {}
}