MetaFun - Pragma ADE

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1.13 Colors
So far, we have seen some colors in graphics. It must be said that METAPOST color model is not that
advanced, although playing with colors in the METAPOST way can be fun. In later chapters we will
discuss some extensions that provide shading.
Colors are defined as vectors with three components: a red, green and blue one. Like pens, colors
have their with--command:
withcolor (.4,.5.,6)
You can define color variables, like:
color darkred ; darkred := (.625,0.0) ;
You can now use this color as:
withcolor darkred
Given that red is already defined, we also could have said:
withcolor .625red
Because for METAPOST colors are just vectors, you can do things similar to points. A color halfway
red and green is therefore accomplished with:
withcolor .5[red,green]
Since only the RGB color space is supported, this is about all we can tell about colors for this moment.
Later we will discuss some nasty details.
1.14 Dashes
A dash pattern is a simple picture that is build out of straight lines. Any slightly more complicated
picture will be reduced to straight lines and a real complicated one is rejected, and in this respect
METAPOST considers a circle to be a complicated path.
The next example demonstrates how to get a dashed line. First we built picture p, that we apply
to a path. Here we use a straight path, but dashing can be applied to any path.
picture p ; p := nullpicture ;
addto p doublepath ((0,0)--(3mm,3mm)) shifted (6mm,6mm) ;
draw (0,0)--(10cm,0) dashed p withpen pencircle scaled 1mm ;
This way of defining a pattern is not that handy, especially if you start wondering why you need
to supply a slanted path. Therefore, METAPOST provides a more convenient mechanism to define a
pattern.
picture p ; p := dashpattern(on 3mm off 3mm) ;
draw (0,0)--(10cm,0) dashed p withpen pencircle scaled 1mm ;
Welcome to MetaPost Colors