TikZ and wrong drawing order

TikZ and wrong drawing order

[Mojca Miklavec]

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Hi,

I would like to ask for help for either finding a fix or some clever
workaround for the following problem.

If I use a TikZ picture as item symbol and additionally use background
text, then the first symbol in itemize environment gets covered by the
background. Here's an example:

\usemodule
    [tikz]

\definesymbol[1]
    [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]

\definecolor
    [backcol]
    [s=1,a=1,t=0.1]

\starttext

\startframedtext[width=4cm,background=color,backgroundcolor=backcol]
\startitemize
\item one
\item two
\item three
\stopitemize
\stopframedtext

\stoptext

Thank you,
    Mojca

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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Aditya Mahajan]

On Thu, 11 Jun 2015, Mojca Miklavec wrote:

> Hi,
>
> I would like to ask for help for either finding a fix or some clever
> workaround for the following problem.
>
> If I use a TikZ picture as item symbol and additionally use background
> text, then the first symbol in itemize environment gets covered by the
> background. Here's an example:
>
> \usemodule
>    [tikz]
>
> \definesymbol[1]
>    [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>
> \definecolor
>    [backcol]
>    [s=1,a=1,t=0.1]
>
> \starttext
>
> \startframedtext[width=4cm,background=color,backgroundcolor=backcol]
> \startitemize
> \item one
> \item two
> \item three
> \stopitemize
> \stopframedtext
>
> \stoptext

Workaround (though I have no idea why this should work). Use

    background={foreground,color}

I wanted to test background={color, foreground}, but wrote the above by 
mistake and it works!!!

Aditya

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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Thu, Jun 11, 2015 at 7:59 PM, Aditya Mahajan wrote:
> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>
>> Hi,
>>
>> I would like to ask for help for either finding a fix or some clever
>> workaround for the following problem.
>>
>> If I use a TikZ picture as item symbol and additionally use background
>> text, then the first symbol in itemize environment gets covered by the
>> background. Here's an example:
>>
>> \usemodule
>>    [tikz]
>>
>> \definesymbol[1]
>>    [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>>
>> \definecolor
>>    [backcol]
>>    [s=1,a=1,t=0.1]
>>
>> \starttext
>>
>> \startframedtext[width=4cm,background=color,backgroundcolor=backcol]
>> \startitemize
>> \item one
>> \item two
>> \item three
>> \stopitemize
>> \stopframedtext
>>
>> \stoptext
>
>
> Workaround (though I have no idea why this should work).

Does it also work if you use the following?

\definecolor
    [backcol]
    [s=1,a=1,t=0.95]

> Use
>
>    background={foreground,color}
>
> I wanted to test background={color, foreground}, but wrote the above by
> mistake and it works!!!

While it works in the sense that it gives a consistent look, it
doesn't really lead to the desired result, at least not for me. The
reason for using background colour in my case was to make text
"visible" on a dark background photo. It doesn't really help if the
main text gets hidden behind the semi-transparent layer.

Unless you get different results than I do.

Mojca
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Aditya Mahajan]

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On Thu, 11 Jun 2015, Mojca Miklavec wrote:

> On Thu, Jun 11, 2015 at 7:59 PM, Aditya Mahajan wrote:
>> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>>
>>> Hi,
>>>
>>> I would like to ask for help for either finding a fix or some clever
>>> workaround for the following problem.
>>>
>>> If I use a TikZ picture as item symbol and additionally use background
>>> text, then the first symbol in itemize environment gets covered by the
>>> background. Here's an example:
>>>
>>
>> Workaround (though I have no idea why this should work).
>
>>    background={foreground,color}
>
> While it works in the sense that it gives a consistent look, it
> doesn't really lead to the desired result, at least not for me. The
> reason for using background colour in my case was to make text
> "visible" on a dark background photo. It doesn't really help if the
> main text gets hidden behind the semi-transparent layer.

I have no idea what tikz is doing:

\usemodule[tikz]

\definecolor[light][s=1,a=1,t=0.1]
\definecolor[dark] [s=1,a=1,t=0.95]

\defineframedtext[normal] [width=4cm, background=color]
\defineframedtext[reverse][width=4cm, background={foreground,color}]

\startbuffer
\tikz\fill[color=blue] (0,0) circle (.2cm);
\startMPcode fill fullcircle scaled (.4cm) withcolor \MPcolor{blue}; \stopMPcode
\stopbuffer

\starttext

\startnormal[backgroundcolor=light] \getbuffer \stopnormal
\startnormal[backgroundcolor=dark] \getbuffer  \stopnormal

\blank[3*line]

\startreverse[backgroundcolor=light] \getbuffer \stopreverse
\startreverse[backgroundcolor=dark] \getbuffer  \stopreverse
\stoptext

Aditya

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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Thu, Jun 11, 2015 at 10:43 PM, Aditya Mahajan wrote:
> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>> On Thu, Jun 11, 2015 at 7:59 PM, Aditya Mahajan wrote:
>>> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>>>
>>>> Hi,
>>>>
>>>> I would like to ask for help for either finding a fix or some clever
>>>> workaround for the following problem.
>>>>
>>>> If I use a TikZ picture as item symbol and additionally use background
>>>> text, then the first symbol in itemize environment gets covered by the
>>>> background. Here's an example:
>>>>
>>>
>>> Workaround (though I have no idea why this should work).
>>
>>
>>>    background={foreground,color}
>>
>>
>> While it works in the sense that it gives a consistent look, it
>> doesn't really lead to the desired result, at least not for me. The
>> reason for using background colour in my case was to make text
>> "visible" on a dark background photo. It doesn't really help if the
>> main text gets hidden behind the semi-transparent layer.
>
>
> I have no idea what tikz is doing:
>
> \usemodule[tikz]
>
> \definecolor[light][s=1,a=1,t=0.1]
> \definecolor[dark] [s=1,a=1,t=0.95]
>
> \defineframedtext[normal] [width=4cm, background=color]
> \defineframedtext[reverse][width=4cm, background={foreground,color}]
>
> \startbuffer
> \tikz\fill[color=blue] (0,0) circle (.2cm);
> \startMPcode fill fullcircle scaled (.4cm) withcolor \MPcolor{blue};
> \stopMPcode
> \stopbuffer
>
> \starttext
>
> \startnormal[backgroundcolor=light] \getbuffer \stopnormal
> \startnormal[backgroundcolor=dark] \getbuffer  \stopnormal
>
> \blank[3*line]
>
> \startreverse[backgroundcolor=light] \getbuffer \stopreverse
> \startreverse[backgroundcolor=dark] \getbuffer  \stopreverse
> \stoptext

It's even more weird than that. The colour of the first item behind
the "dark" depends on the colour of "light":

\usemodule[tikz]

\definecolor[extralight][s=1,a=1,t=0.1]
\definecolor[light][s=1,a=1,t=0.6]
\definecolor[dark] [s=1,a=1,t=0.95]

\defineframedtext[normal] [width=6cm, background=color]
\defineframedtext[reverse][width=6cm, background={foreground,color}]

\startbuffer
\tikz\fill[color=blue] (0,0) circle (.2cm);%
\startMPcode fill fullcircle scaled (.4cm) withcolor \MPcolor{blue}; \stopMPcode
\tikz\fill[color=blue] (0,0) circle (.2cm);
\stopbuffer

\starttext

\startnormal[backgroundcolor=light] \getbuffer \stopnormal
\startnormal[backgroundcolor=dark] \getbuffer  \stopnormal

\blank[2*line]

\startreverse[backgroundcolor=light] \getbuffer \stopreverse
\startreverse[backgroundcolor=dark] \getbuffer different \stopreverse

\blank[2*line]

\startreverse[backgroundcolor=extralight] \getbuffer \stopreverse
\startreverse[backgroundcolor=dark] \getbuffer from this one \stopreverse
\stoptext

Mojca
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/11/2015 7:27 PM, Mojca Miklavec wrote:
> Hi,
>
> I would like to ask for help for either finding a fix or some clever
> workaround for the following problem.
>
> If I use a TikZ picture as item symbol and additionally use background
> text, then the first symbol in itemize environment gets covered by the
> background. Here's an example:
>
> \usemodule
>      [tikz]
>
> \definesymbol[1]
>      [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]

\startreusableMPgraphic{bullet}
     fill fullcircle
         scaled (1EmWidth)
         withshademethod "circular"
         withcolor red shadedinto blue ;
\stopreusableMPgraphic

\definesymbol[1]{\reuseMPgraphic{bullet}}

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/11/2015 10:14 PM, Mojca Miklavec wrote:
> On Thu, Jun 11, 2015 at 7:59 PM, Aditya Mahajan wrote:
>> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>>
>>> Hi,
>>>
>>> I would like to ask for help for either finding a fix or some clever
>>> workaround for the following problem.
>>>
>>> If I use a TikZ picture as item symbol and additionally use background
>>> text, then the first symbol in itemize environment gets covered by the
>>> background. Here's an example:
>>>
>>> \usemodule
>>>     [tikz]
>>>
>>> \definesymbol[1]
>>>     [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>>>
>>> \definecolor
>>>     [backcol]
>>>     [s=1,a=1,t=0.1]
>>>
>>> \starttext
>>>
>>> \startframedtext[width=4cm,background=color,backgroundcolor=backcol]
>>> \startitemize
>>> \item one
>>> \item two
>>> \item three
>>> \stopitemize
>>> \stopframedtext
>>>
>>> \stoptext
>>
>>
>> Workaround (though I have no idea why this should work).
>
> Does it also work if you use the following?
>
> \definecolor
>      [backcol]
>      [s=1,a=1,t=0.95]
>
>> Use
>>
>>     background={foreground,color}
>>
>> I wanted to test background={color, foreground}, but wrote the above by
>> mistake and it works!!!
>
> While it works in the sense that it gives a consistent look, it
> doesn't really lead to the desired result, at least not for me. The
> reason for using background colour in my case was to make text
> "visible" on a dark background photo. It doesn't really help if the
> main text gets hidden behind the semi-transparent layer.
>
> Unless you get different results than I do.

i suppose that tikz puts some pdf code in the output stream and this is 
likely to interfere with the way context deals with colors

a solution is:

{\red x\dontleavehmode\forcecolorhack\tikz\fill[color=blue] (0,0) circle 
(.2cm);x}

the

\forcecolorhack

is, well, a hack that fools the optimizer and \dontleavehmode is needed 
to get tex in the right mode

i have no time to look into the internals of tikz to see if a different 
trick is possible

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Thu, Jun 11, 2015 at 11:12 PM, Hans Hagen wrote:
> On 6/11/2015 7:27 PM, Mojca Miklavec wrote:
>>
>> \usemodule
>>      [tikz]
>>
>> \definesymbol[1]
>>      [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>
>
> \startreusableMPgraphic{bullet}
>     fill fullcircle
>         scaled (1EmWidth)
>         withshademethod "circular"
>         withcolor red shadedinto blue ;
> \stopreusableMPgraphic
>
> \definesymbol[1]{\reuseMPgraphic{bullet}}

Thank you. But TikZ simply delivers a "superior" result in this case
(= better tuned). We should figure out how exactly the shading is done
there (it's slightly eccentric etc.) and try to prepare a macro for
metafun that delivers the same result (or at least a compatible one)
with an input of a single colour as a parameter.

Mojca
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/12/2015 12:28 AM, Mojca Miklavec wrote:
> On Thu, Jun 11, 2015 at 11:12 PM, Hans Hagen wrote:
>> On 6/11/2015 7:27 PM, Mojca Miklavec wrote:
>>>
>>> \usemodule
>>>       [tikz]
>>>
>>> \definesymbol[1]
>>>       [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>>
>>
>> \startreusableMPgraphic{bullet}
>>      fill fullcircle
>>          scaled (1EmWidth)
>>          withshademethod "circular"
>>          withcolor red shadedinto blue ;
>> \stopreusableMPgraphic
>>
>> \definesymbol[1]{\reuseMPgraphic{bullet}}
>
> Thank you. But TikZ simply delivers a "superior" result in this case
> (= better tuned). We should figure out how exactly the shading is done
> there (it's slightly eccentric etc.) and try to prepare a macro for
> metafun that delivers the same result (or at least a compatible one)
> with an input of a single colour as a parameter.

Most shades look ugly and useless to me anyway but you have more control 
than you think (always had but nicer interfaced in mpiv):

\startMPpage
     fill fullcircle scaled 10cm
         withshademethod "circular"
         withshadevector (5cm,1cm)
         withshadecenter (.1,.5)
         withshadedomain (.2,.6)
         withshadefactor 1.2
         withshadecolors (red,green)
     ;
\stopMPage

Of course you need to play with the values as there is no 'best' 
combination.

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Alan BRASLAU]

On Fri, 12 Jun 2015 00:28:43 +0200
Mojca Miklavec <mojca.miklavec.lists@gmail.com> wrote:

> Thank you. But TikZ simply delivers a "superior" result in this case
> (= better tuned). 

Pfluff!

Alan
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Thu, Jun 11, 2015 at 11:26 PM, Hans Hagen wrote:
>>> On Thu, 11 Jun 2015, Mojca Miklavec wrote:
>>>
>>>> Hi,
>>>>
>>>> I would like to ask for help for either finding a fix or some clever
>>>> workaround for the following problem.
>>>>
>>>> If I use a TikZ picture as item symbol and additionally use background
>>>> text, then the first symbol in itemize environment gets covered by the
>>>> background. Here's an example:
>>>>
>>>> \usemodule
>>>>     [tikz]
>>>>
>>>> \definesymbol[1]
>>>>     [{\tikz\shade[shading=ball,ball color=blue] (0,0) circle (.2cm);}]
>>>>
>>>> \definecolor
>>>>     [backcol]
>>>>     [s=1,a=1,t=0.1]
>>>>
>>>> \starttext
>>>>
>>>> \startframedtext[width=4cm,background=color,backgroundcolor=backcol]
>>>> \startitemize
>>>> \item one
>>>> \item two
>>>> \item three
>>>> \stopitemize
>>>> \stopframedtext
>>>>
>>>> \stoptext
>
> i suppose that tikz puts some pdf code in the output stream and this is
> likely to interfere with the way context deals with colors
>
> a solution is:
>
> {\red x\dontleavehmode\forcecolorhack\tikz\fill[color=blue] (0,0) circle
> (.2cm);x}
>
> the
>
> \forcecolorhack
>
> is, well, a hack that fools the optimizer and \dontleavehmode is needed to
> get tex in the right mode

Thank you very much. Using the following worked fine as a workaround.

\definesymbol[1]
    [{\dontleavehmode\forcecolorhack\tikz\shade[shading=ball,ball
color=blue] (0,0) circle (.2cm);}]

Meanwhile I filed a ticket to the pgf's bug tracker to help us
remember specifics about the problem.

Mojca
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Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Fri, Jun 12, 2015 at 12:45 AM, Hans Hagen wrote:
>
> Most shades look ugly and useless to me anyway but you have more control
> than you think (always had but nicer interfaced in mpiv):
>
> \startMPpage
>     fill fullcircle scaled 10cm
>         withshademethod "circular"
>         withshadevector (5cm,1cm)
>         withshadecenter (.1,.5)
>         withshadedomain (.2,.6)
>         withshadefactor 1.2
>         withshadecolors (red,green)
>     ;
> \stopMPage

Great, I love the new syntax (compared to the MKII "ugliness" of shadings).

But how does one declare more than one colour? In particular, how
would you do the following in MP?

\usemodule
    [tikz]

\pgfdeclareverticalshading{rainbow}{100bp}{
    color(0bp)=(red);
    color(25bp)=(red);
    color(35bp)=(yellow);
    color(45bp)=(green);
    color(55bp)=(cyan);
    color(65bp)=(blue);
    color(75bp)=(violet);
    color(100bp)=(violet)}

\starttext
\starttikzpicture[shading=rainbow]
\shade[shading angle=90] (0,0) rectangle +(10,1);
\stoptikzpicture
\stoptext

> Of course you need to play with the values as there is no 'best'
> combination.

This is how TikZ defines the ball:

\pgfdeclareradialshading[tikz@ball]{ball}{\pgfqpoint{-10bp}{10bp}}{%
 color(0bp)=(tikz@ball!15!white);
 color(9bp)=(tikz@ball!75!white);
 color(18bp)=(tikz@ball!70!black);
 color(25bp)=(tikz@ball!50!black);
 color(50bp)=(black)}

Your example uses just two colours, while TikZ uses five and I don't
know how to translate this "ball shading" to MP (I know or at least
knew how to do it in plain PostScript and could dig it up; I think it
uses function shading with predefined colours at predefined distances,
but it's all a single shading (a single function), not a composition
of multiple sections).

Mojca
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

See also:
    http://tex.stackexchange.com/questions/54193/how-to-draw-a-shaded-sphere

Mojca
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Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/14/2015 11:26 PM, Mojca Miklavec wrote:
> On Fri, Jun 12, 2015 at 12:45 AM, Hans Hagen wrote:
>>
>> Most shades look ugly and useless to me anyway but you have more control
>> than you think (always had but nicer interfaced in mpiv):
>>
>> \startMPpage
>>      fill fullcircle scaled 10cm
>>          withshademethod "circular"
>>          withshadevector (5cm,1cm)
>>          withshadecenter (.1,.5)
>>          withshadedomain (.2,.6)
>>          withshadefactor 1.2
>>          withshadecolors (red,green)
>>      ;
>> \stopMPage
>
> Great, I love the new syntax (compared to the MKII "ugliness" of shadings).

well, even mkii could do some magic if one went a bit more low level

shading is quite old actually (dates from before tikz showed up -)

i have in my mailbox a mail from 1999 from mathew that demos a function 
shading (some perl code) which is the way to go with more advanced shades

> But how does one declare more than one colour? In particular, how
> would you do the following in MP?
>
> \usemodule
>      [tikz]
>
> \pgfdeclareverticalshading{rainbow}{100bp}{
>      color(0bp)=(red);
>      color(25bp)=(red);
>      color(35bp)=(yellow);
>      color(45bp)=(green);
>      color(55bp)=(cyan);
>      color(65bp)=(blue);
>      color(75bp)=(violet);
>      color(100bp)=(violet)}
>
> \starttext
> \starttikzpicture[shading=rainbow]
> \shade[shading angle=90] (0,0) rectangle +(10,1);
> \stoptikzpicture
> \stoptext

you're one of those people infected by apple software where shades are 
(of maybe were) the fashion (next thing you will ask to simulate 
perkament behind your pages or leather looking cover pages) ... aka 
patterns in ps

>> Of course you need to play with the values as there is no 'best'
>> combination.
>
> This is how TikZ defines the ball:
>
> \pgfdeclareradialshading[tikz@ball]{ball}{\pgfqpoint{-10bp}{10bp}}{%
>   color(0bp)=(tikz@ball!15!white);
>   color(9bp)=(tikz@ball!75!white);
>   color(18bp)=(tikz@ball!70!black);
>   color(25bp)=(tikz@ball!50!black);
>   color(50bp)=(black)}

that's mostly a shade made out of steps (in the pdf one shade operation 
but not better than 8 shades next to each other) ... personally i 
dislike such granular shaded (either do it good or don't do it at all)

(btw in context code will look a bit more complex because we also need 
to deal with spot colors, multi-tones, cmyk, etc)

> Your example uses just two colours, while TikZ uses five and I don't
> know how to translate this "ball shading" to MP (I know or at least
> knew how to do it in plain PostScript and could dig it up; I think it
> uses function shading with predefined colours at predefined distances,
> but it's all a single shading (a single function), not a composition
> of multiple sections).

something similar to

<</Shading << /Sh <<
   /ShadingType 2
   /ColorSpace
   /DeviceRGB
   /Domain [0.0 100.00128]
   /Coords [0 0.0 0 100.00128]
   /Function <<
     /FunctionType 3
     /Domain [0.0 100.00128]
     /Functions [
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 0 0] /C1 [1 0 
0] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 0 0] /C1 [1 1 
0] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 1 0] /C1 [0 1 
0] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 1 0] /C1 [0 1 
1] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 1 1] /C1 [0 0 
1] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 0 1] /C1 [0 0 
0] /N 1 >>
       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 0 0] /C1 [0 0 
0] /N 1 >>
     ]
   /Bounds [ 25.00032 35.00043 45.00056 55.00069 65.00082 75.00096]
   /Encode [0 1  0 1 0 1 0 1 0 1 0 1 0 1] >>
   /Extend [false false]
 >> >>/ProcSet[/PDF] >>

not too hard to program (if i can motivate myself)
	
Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Mon, Jun 15, 2015 at 9:43 AM, Hans Hagen wrote:
> On 6/14/2015 11:26 PM, Mojca Miklavec wrote:
>>
>> On Fri, Jun 12, 2015 at 12:45 AM, Hans Hagen wrote:
>>>
>>>
>>> Most shades look ugly and useless to me anyway but you have more control
>>> than you think (always had but nicer interfaced in mpiv):
>>>
>>> \startMPpage
>>>      fill fullcircle scaled 10cm
>>>          withshademethod "circular"
>>>          withshadevector (5cm,1cm)
>>>          withshadecenter (.1,.5)
>>>          withshadedomain (.2,.6)
>>>          withshadefactor 1.2
>>>          withshadecolors (red,green)
>>>      ;
>>> \stopMPage
>>
>>
>> Great, I love the new syntax (compared to the MKII "ugliness" of
>> shadings).
>
>
> well, even mkii could do some magic if one went a bit more low level

I know. The resulting PDF was great, but doing any programming in MkII
was a nightmare.

> shading is quite old actually (dates from before tikz showed up -)

TikZ is a relatively recent piece of software.

> i have in my mailbox a mail from 1999 from mathew that demos a function
> shading (some perl code) which is the way to go with more advanced shades
>
>> But how does one declare more than one colour? In particular, how
>> would you do the following in MP?
>>
>> \usemodule
>>      [tikz]
>>
>> \pgfdeclareverticalshading{rainbow}{100bp}{
>>      color(0bp)=(red);
>>      color(25bp)=(red);
>>      color(35bp)=(yellow);
>>      color(45bp)=(green);
>>      color(55bp)=(cyan);
>>      color(65bp)=(blue);
>>      color(75bp)=(violet);
>>      color(100bp)=(violet)}
>>
>> \starttext
>> \starttikzpicture[shading=rainbow]
>> \shade[shading angle=90] (0,0) rectangle +(10,1);
>> \stoptikzpicture
>> \stoptext
>
>
> you're one of those people infected by apple software where shades are (of
> maybe were) the fashion

Actually, some shadings in PDF are broken in Apple's libraries. The
output of Asymptote (and some output of my own simulations) can
sometimes only be rendered properly by Acrobat, while Apple software
would simply crash or render pure nonsense.

> (next thing you will ask to simulate perkament
> behind your pages or leather looking cover pages) ... aka patterns in ps

Thanks for the idea ;)

>>> Of course you need to play with the values as there is no 'best'
>>> combination.
>>
>>
>> This is how TikZ defines the ball:
>>
>> \pgfdeclareradialshading[tikz@ball]{ball}{\pgfqpoint{-10bp}{10bp}}{%
>>   color(0bp)=(tikz@ball!15!white);
>>   color(9bp)=(tikz@ball!75!white);
>>   color(18bp)=(tikz@ball!70!black);
>>   color(25bp)=(tikz@ball!50!black);
>>   color(50bp)=(black)}
>
>
> that's mostly a shade made out of steps (in the pdf one shade operation but
> not better than 8 shades next to each other)

8 shades next to each other are probably less efficient and might
render with "holes" in non-Acrobat buggy renderers. But your example
below looks like it should be interpreted as a "single shading" (it
uses a single function), so it should work fine.

What is the decimal part (".00128") used for?

> ... personally i dislike such
> granular shaded (either do it good or don't do it at all)
>
> (btw in context code will look a bit more complex because we also need to
> deal with spot colors, multi-tones, cmyk, etc)
>
>> Your example uses just two colours, while TikZ uses five and I don't
>> know how to translate this "ball shading" to MP (I know or at least
>> knew how to do it in plain PostScript and could dig it up; I think it
>> uses function shading with predefined colours at predefined distances,
>> but it's all a single shading (a single function), not a composition
>> of multiple sections).
>
>
> something similar to
>
> <</Shading << /Sh <<
>   /ShadingType 2
>   /ColorSpace
>   /DeviceRGB
>   /Domain [0.0 100.00128]
>   /Coords [0 0.0 0 100.00128]
>   /Function <<
>     /FunctionType 3
>     /Domain [0.0 100.00128]
>     /Functions [
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 0 0] /C1 [1 0 0] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 0 0] /C1 [1 1 0] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [1 1 0] /C1 [0 1 0] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 1 0] /C1 [0 1 1] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 1 1] /C1 [0 0 1] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 0 1] /C1 [0 0 0] /N
> 1 >>
>       << /FunctionType 2 /Domain [0.0 100.00128] /C0 [0 0 0] /C1 [0 0 0] /N
> 1 >>
>     ]
>   /Bounds [ 25.00032 35.00043 45.00056 55.00069 65.00082 75.00096]
>   /Encode [0 1  0 1 0 1 0 1 0 1 0 1 0 1] >>
>   /Extend [false false]
>>> >>/ProcSet[/PDF] >>
>
> not too hard to program (if i can motivate myself)

Talking about old examples ... here's an example in pure PostScript
that achieves a desired result, including your response (however it
doesn't support specifying the locations of colours):
    http://www.ntg.nl/pipermail/ntg-context/2006/022833.html

Mojca
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Re: TikZ and wrong drawing order

[Alan BRASLAU]

On Mon, 15 Jun 2015 09:43:38 +0200
Hans Hagen <pragma@wxs.nl> wrote:

> you're one of those people infected by apple software where shades
> are (of maybe were) the fashion 

Eye candy, goes in and out of fashion...
 
> that's mostly a shade made out of steps (in the pdf one shade
> operation but not better than 8 shades next to each other) 

8 shades of gray?

Alan
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Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/14/2015 11:26 PM, Mojca Miklavec wrote:

> Your example uses just two colours, while TikZ uses five and I don't
> know how to translate this "ball shading" to MP (I know or at least
> knew how to do it in plain PostScript and could dig it up; I think it
> uses function shading with predefined colours at predefined distances,
> but it's all a single shading (a single function), not a composition
> of multiple sections).

Ok, as I suppose you need it for you thesis ... a new beta ...

I didn't play with values for the circular one but here's a linear:

\startMPpage

     fill fullsquare scaled 50pt
         withshademethod "linear"
         withshadevector (0,1)
         withshadestep (
             withshadefraction .3
             withshadecolors (red,green)
         )
         withshadestep (
             withshadefraction .5
             withshadecolors (green,blue)
         )
         withshadestep (
             withshadefraction .7
             withshadecolors (blue,red)
         )
         withshadestep (
             withshadefraction 1
             withshadecolors (red,yellow)
         )
     ;

     fill fullsquare scaled 50pt shifted(60pt,0)
         withshademethod "linear"
         withshadevector (0,1)
         withshadecolors (red,green)
     ;

\stopMPpage

so the withshadestep is new

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Hans Hagen]

On 6/15/2015 10:02 AM, Mojca Miklavec wrote:

> What is the decimal part (".00128") used for?

it's what tikz produces as output ... a rounding error i guess

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: TikZ and wrong drawing order

[Mojca Miklavec]

On Mon, Jun 15, 2015 at 3:02 PM, Hans Hagen wrote:
> On 6/15/2015 10:02 AM, Mojca Miklavec wrote:
>
>> What is the decimal part (".00128") used for?
>
> it's what tikz produces as output ... a rounding error i guess

Ah, ok, I din't know that you were using the TikZ output.

Then it's more likely related to "bigpoint" (bp), but that's pure speculation.

Mojca
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