On Sat, Nov 1, 2008 at 1:38 AM, Renaud Aubin <aubin@nibua-r.org> wrote:

> Hi,
>
> I have some trouble using a gradient background (solid) with a
> transparent element :
>
>  \startMPinclusions
>    def test_shade (expr a, b) =
>    pickup pencircle scaled 1mm ;
>    color ca ; ca := \MPcolor{a} ;
>    color cb ; cb := \MPcolor{b} ;
>    color cc ; cc := \MPcolor{c} ;
>    sh := define_linear_shade(origin
> shifted(0cm,.5*\overlayheight),origin,ca,cb) ;
>    fill fullsquare xscaled \overlaywidth yscaled \overlayheight
> withshade sh;
>    draw origin withcolor cc;
>    draw origin shifted(0cm,-.25*\overlayheight) withcolor cc;
>    enddef ;
>  \stopMPinclusions
>
>  \setupcolors[state=start]
>  \definecolor[a][r=.57254902,g=.784313725,b=.917647059]
>  \definecolor[b][white]
>  \definecolor[c][darkred]
>  \starttext
>
>  \defineoverlay[bgoverlay][\uniqueMPgraphic{bg_top_shade}]
>  \setupbackgrounds[page][background=bgoverlay]
>  \startuniqueMPgraphic{bg_top_shade}
>    test_shade(origin, origin shifted(0cm,1cm));
>    draw fullcircle scaled 10cm shifted (0cm,0.25*\overlayheight)
> withcolor transparent(1,0.5,white) withpen pencircle scaled 2cm;
>
> %%%%%%%% If you comment out the previous line the color rendering is
> definitelly different...
>
>  \stopuniqueMPgraphic
>
>  \input knuth
>
> \stoptext
>

This is my test.
Where is the problem ?

minimals-beta
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luigi