MetaFun - Pragma ADE

14
A zscaled specification takes a vector as argument:
p zscaled (2,.5)
The result looks like a combination of scaling and rotation, and conforms to the formula in the
previous table.
Transformations can be defined in terms of a transform matrix. Such a matrix is stored in a transform
variable. For example:
transform t ; t := identity scaled 2cm shifted (4cm,1cm) ;
We use the associated keyword transformed to apply this matrix to a path or picture.
p transformed t
In this example we've taken the identity matrix as starting point but you can use any predefined
transformation. The identity matrix is defined in such a way that it scales by a factor of one in both
directions and shifts over the zero--vector.
Transform variables can save quite some typing and may help you to force consistency when many
similar transformations are to be done. Instead of changing the scaling, shifting and other transformations
you can then stick to just changing the one transform variable.
1.3 Constructing paths
In most cases, a path will have more points than the few shown here. Take for instance a so called
super ellipse.
4
3
5
These graphics provide a lot of information. In this picture the crosshair in the center is the origin
and the dashed rectangle is the bounding box of the super ellipse. The bounding box specifies the
position of the graphic in relation to the origin as well as its width and height.
In the graphic on the right, you can see the points that make up the closed path as well as the
control points. Each point has a number with the first point numbered zero. Because the path is
closed, the first and last point coincide.
We've used the commands .. and -- as path connecting directives. In the next series of examples,
we will demonstrate a few more. However, before doing that, we define a few points, using the
predefined z variables.
Welcome to MetaPost Constructing paths
2
6
0
1
7
8