Re: [NTG-context] Shading to transparent using withshademethod

28 Jan 2016


      On 1/28/2016 11:45 AM, Marco Patzer wrote:
...
On Thu, 28 Jan 2016 09:43:24 +0100
Hans Hagen  wrote:
...
On 1/27/2016 10:05 PM, Marco Patzer wrote:
...
The new code appears to work in general, but only if no shading to
transparent is being used:
\definecolor [trans] [a=multiply, t=.5, s=.5]
\starttext
    \startMPcode
      % works
      fill fullcircle scaled 10cm withcolor \MPcolor{trans};
fill fullsquare xyscaled (15cm, 15cm)
        withshademethod "linear"
        withshadevector (0,1)
        % works
        withshadecolors (red,\MPcolor{blue})
        % fails
        %% withshadecolors (red,\MPcolor{trans})
        ;
    \stopMPcode
\stoptext
How to make transparent shadings work with the new mechanism?
withtransparency (1,.5)
However, this makes the entire shade transparent. How to shade from
one colour to transparent using withtransparency to achieve an
effect like in the example below?
that isn't how shading works, it's a vector from one color to the other 
(same color space eventually) and transparency is a property of the whole
...
\definecolor      [trans] [a=multiply, t=0]
\setupbackgrounds [page]  [background=color, backgroundcolor=lightgray]
\starttext
   \startMPcode
   fill fullsquare xyscaled (15cm, 15cm)
     withshademethod "linear"
     withshadevector (0, 1)
     %% colour doens't match
     %% withshadecolors (red, lightgray)
     %% output is ok with \MPcolor
     withshadecolors (red, \MPcolor{lightgray})
     %% ??
     %% withtransparency (1, .5)
     ;
   \stopMPcode
\stoptext
Furthermore, why do the tex and MP colours differ? Wouldn't it make
sense to use the same colour definitions? Or was that intentional?
it's already hard enough to have what we have now (tex and mp are 
different species)


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