Shading to transparent using withshademethod

Marco Patzer

27 Jan 2016 27 Jan '16

9:05 p.m.

Hi, some months ago the withshading, withfromshadecolor etc. have apparently been replaced by the more general withshademethod, withshadevector, withshadecolors, etc. methods. I have issues converting the old withshading code to the withshademethod version. The old code had no problems shading to transparent: \definecolor [trans] [a=multiply, t=.5, s=.5] \starttext \startMPcode path p; p:=fullsquare xyscaled (8cm, 8cm); fill p withshading("linear", ulcorner p, llcorner p) withfromshadecolor \MPcolor{black} withtoshadecolor \MPcolor{trans}; \stopMPcode \stoptext 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? Marco

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Hans Hagen

28 Jan 28 Jan

8:43 a.m.

On 1/27/2016 10:05 PM, Marco Patzer wrote:

...

Hi,

some months ago the withshading, withfromshadecolor etc. have apparently been replaced by the more general withshademethod, withshadevector, withshadecolors, etc. methods.

I have issues converting the old withshading code to the withshademethod version. The old code had no problems shading to transparent:

\definecolor [trans] [a=multiply, t=.5, s=.5] \starttext \startMPcode path p; p:=fullsquare xyscaled (8cm, 8cm); fill p withshading("linear", ulcorner p, llcorner p) withfromshadecolor \MPcolor{black} withtoshadecolor \MPcolor{trans}; \stopMPcode \stoptext

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)

...

Marco ___________________________________________________________________________________ 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 webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________

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

Marco Patzer

10:45 a.m.

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? \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? Marco

Hans Hagen

11:33 a.m.

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) ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------

Marco Patzer

12:53 p.m.

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'

...

it's a vector from one color to the other (same color space eventually) and transparency is a property of the whole

That's how the new mechanism works, apparently. But transparency can AFAIK also be a property of the colour. So transparency is a vector from one colour to the other, each possibly being partly or entirely transparent. But as I don't understand the inner internals, I believe there's a good reason this has been changed. Marco

Hans Hagen

1:45 p.m.

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? a shade goes from one color to another; transparency is not part of that but applied to the whole (transparency is kind of independent of color and in context also only coupled in definition not in implementation)

...

...
it's a vector from one color to the other (same color space eventually) and transparency is a property of the whole

That's how the new mechanism works, apparently. But transparency can AFAIK also be a property of the colour. So transparency is a vector from one colour to the other, each possibly being partly or entirely transparent.

no, it's independent ... and in shades one talks of color spaces (need to be the same too) so in context we even need to make sure an rgb to cmyk shade goes well

...

But as I don't understand the inner internals, I believe there's a good reason this has been changed.

cleaner Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------

Marco Patzer

2:34 p.m.

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. Marco

Hans Hagen

5:26 p.m.

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 \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; 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} ; \stopMPcode \stoptext \stopbuffer \starttext \typebuffer\getbuffer \stoptext ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------

Marco Patzer

6:09 p.m.

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

Hans Hagen

11:29 a.m.

On 1/28/2016 9:43 AM, Hans Hagen wrote:

...

On 1/27/2016 10:05 PM, Marco Patzer wrote:

...
Hi,

some months ago the withshading, withfromshadecolor etc. have apparently been replaced by the more general withshademethod, withshadevector, withshadecolors, etc. methods.

I have issues converting the old withshading code to the withshademethod version. The old code had no problems shading to transparent:

\definecolor [trans] [a=multiply, t=.5, s=.5] \starttext \startMPcode path p; p:=fullsquare xyscaled (8cm, 8cm); fill p withshading("linear", ulcorner p, llcorner p) withfromshadecolor \MPcolor{black} withtoshadecolor \MPcolor{trans}; \stopMPcode \stoptext

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)

next beta \definecolor [trans] [a=multiply, t=.5, g=.5] \startMPpage fill fullcircle scaled 12cm withcolor \MPcoloronly{trans}; fill fullcircle scaled 10cm withcolor \MPcolor{trans}; fill fullsquare xyscaled (15cm, 15cm) withshademethod "linear" withshadevector (0,1) withshadecolors (red,\MPcoloronly{trans}) withtransparency \MPtransparency{trans} ; \stopMPpage ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------

Marco Patzer

1:02 p.m.

On Thu, 28 Jan 2016 12:29:46 +0100 Hans Hagen wrote:

...

...
...
How to make transparent shadings work with the new mechanism?

withtransparency (1,.5)

next beta

\definecolor [trans] [a=multiply, t=.5, g=.5]

\startMPpage fill fullcircle scaled 12cm withcolor \MPcoloronly{trans}; fill fullcircle scaled 10cm withcolor \MPcolor{trans};

fill fullsquare xyscaled (15cm, 15cm) withshademethod "linear" withshadevector (0,1) withshadecolors (red,\MPcoloronly{trans}) withtransparency \MPtransparency{trans} ;

\stopMPpage

I believe the \MPcoloronly and \MPtransparency macros split up the \MPcolor in it's colour and transparency parts. This doesn't really provide a solution to the initial problem as I understand. Rather it seems to be a more robust way to use transparency and prevent choking on colours that might contain transparent parts. I will shade to the background colour then, which is not that clean but works as well. Anyway, thanks for the quick answer and the clarification. Marco

Hans Hagen

3:16 p.m.

On 1/28/2016 2:02 PM, Marco Patzer wrote:

...

On Thu, 28 Jan 2016 12:29:46 +0100 Hans Hagen wrote:

...
...
...
How to make transparent shadings work with the new mechanism?

withtransparency (1,.5)

next beta

\definecolor [trans] [a=multiply, t=.5, g=.5]

\startMPpage fill fullcircle scaled 12cm withcolor \MPcoloronly{trans}; fill fullcircle scaled 10cm withcolor \MPcolor{trans};

fill fullsquare xyscaled (15cm, 15cm) withshademethod "linear" withshadevector (0,1) withshadecolors (red,\MPcoloronly{trans}) withtransparency \MPtransparency{trans} ;

\stopMPpage

I believe the \MPcoloronly and \MPtransparency macros split up the \MPcolor in it's colour and transparency parts.

This doesn't really provide a solution to the initial problem as I understand. Rather it seems to be a more robust way to use transparency and prevent choking on colours that might contain transparent parts.

In the old method we used special mp colors to store all kind of things which wasn't 100% robust either (because some colors were not possible then). Even then internally color and transparency had to be split in mp. The new syntax for shading is extensible. You really don't want to know how extensions like shading and tex text and ... were implemented in mkii metapost.

...

I will shade to the background colour then, which is not that clean but works as well. Anyway, thanks for the quick answer and the clarification.

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

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Shading to transparent using withshademethod

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