MetaFun - Pragma ADE

Figure 8.4 Another clipped cow.
\placefigure
[here][fig:clipped cow 2]
{Another clipped cow.}
{\clip
[width=2cm,height=2cm,hoffset=0cm,voffset=0cm]
{\externalfigure[cow.mps][width=4cm]}}
Because METAPOST supports clipping, it will be no surprise that both techniques can be combined.
In the next example we will zoom in on the head of the cow. We also use this opportunity to
demonstrate how you can package a clip in a figure definition.
\startMPclip{head clip}
w := \width ; h := \height ;
clip currentpicture to
((0,h)--(w,h){down}..{left}(0,0)--cycle) ;
\stopMPclip
\placefigure
[here][fig:circular clipped cowhead]
{A quarter circle applied to a cows head.}
{\ruledhbox
{\clip
[nx=2,ny=2,x=1,y=1,mp=head clip]
{\externalfigure[cow.mps][width=4cm]}}}
A more advanced clip is demonstrated in figure 8.5. We added \ruledhbox to demonstrate the
dimensions of the resulting graphic. Putting something in such a ruled box is often a quick way
to test spacing.
Figure 8.5 A quarter circle applied to
a cows head.
Although a clip path definition can contain any METAPOST command, even graphics, it must contain
at least one clipping path. The first one encountered in the resulting graphic is used. In the
example we used a path that is built out of three subpaths.
(0,h)--(w,h){down}..{left}(0,0)--cycle
Clipping Special effects
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