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

28 Jan 2016


      On Thu, 28 Jan 2016 18:26:28 +0100
Hans Hagen  wrote:
...
On 1/28/2016 3:34 PM, Marco Patzer wrote:
...
On Thu, 28 Jan 2016 14:45:13 +0100
Hans Hagen  wrote:
...
On 1/28/2016 1:53 PM, Marco Patzer wrote:
...
On Thu, 28 Jan 2016 12:33:39 +0100
Hans Hagen  wrote:
...
...
>> 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,
…any longer. I just confirmed that it used to work on an older
installation. Just sayin'
are you sure?
See the attached example. The shade seems to go from black to fully
transparent. So regardless of the background colour the shade looks
fine. I can't replicate this with the new mechanism.
a matter of choosing the colors
Indeed, if you choose the colours wisely you don't necessarily need
transparency (at least in my use case).
...
\unprotect
\def\MPcoloronly#1%
   {\clf_mpcolor
      \attribute\colormodelattribute
      \colo_helpers_inherited_current_ca{#1} %
      \zerocount}
\def\MPtransparency#1%
   {\clf_mpcolor
      \zerocount
      \zerocount
      \colo_helpers_inherited_current_ta{#1} }
\protect
\startbuffer
   \definecolor[tex:bg][s=.85]
   \definecolor[mp:fg] [s=.85,t=1,a=1]
   \setupbackgrounds [page] [background=color,backgroundcolor=tex:bg]
   \starttext
     \contextversion\crlf
     \startMPcode
    % lightgray = 0.85white;
                     ^^^ That looks more like Tex's lightgray
...
fill fullsquare xyscaled (12cm, 12cm)
        withshademethod "linear"
        withshadevector (-1,0)
      % withshadecolors (black,lightgray)
      % withtransparency (1,1)
        withshadecolors (black,\MPcoloronly{mp:fg})
        withtransparency \MPtransparencyonly{mp:fg}
^^^^^  Typo or new feature?
                                         looks like \MPtransparency
                                         should be sufficient
...
;
     \stopMPcode
   \stoptext
\stopbuffer
\starttext
   \typebuffer\getbuffer
\stoptext
I'll play with the code in the new beta.

Marco