or
samcarter
latex3
By default l3draw only supports red, yellow, blue, green, white, black, cyan and magenta (and combinations thereof).

How to define more colours?
samcarter
Under the hood l3draw uses l3color for the colour support, therefore on can use the \color_set:nnn or \color_set:nn macro to define new colours.

One example with an rgb colour (the colour models gray, cmyk and spot are also available) and based on existing colours.


\documentclass{standalone}

\usepackage{l3draw}

\begin{document}

\ExplSyntaxOn

\color_set:nnn {foo} {rgb} {0.5,0.8,1}
\color_set:nn {bar} {yellow!50!red}

\draw_begin:

\draw_path_circle:nn {0cm,0cm} {1cm}
\draw_color_fill:n { foo }
\draw_path_use_clear:n { fill, stroke }

\draw_path_circle:nn {1cm,0cm} {1cm}
\draw_color_fill:n { bar }
\draw_path_use_clear:n { fill, stroke }

\draw_end:
\ExplSyntaxOff

\end{document}

How to define custom colours in l3draw
:)
much better!
better?
mmm, maybe I could simply make two examples. Let me try...
then you could say by the "family" or something like that. \color_set:nn is like \colorlet and \color_set:nnn is like \definecolor, so they are quite similar in their result but different in their inner workings.
But how to decide how many n's to use? The macro exists both for nn and nnn (I hoped I could duck this decision by only taking the front part )
Imho, in text you should call l3-macros by their base-name which includes the arguments \color_set:nnn instead of \color_set.