graphics

graphics

[Hans Hagen]

Hi,

As most mechanism are reasonable okay now we can look into what future 
versions of ConteXt should provide in terms of functionality. The 
(luatex) engine is also more of less finished or at least stable in 
terms of functionality.

One possible area of further development is graphics so I'd like to know 
if there are (reasonable) demands for more graphics support using 
metapost. Alan and I are on-and-off working on some extensions and one 
of the things we discuss is visualization of data. The question is of 
course what should be done in the lua/mp/tex combination and what 
externally but the combination has some advantages. There has been 
presentations and discussions at the last meeting and graphics is always 
a nice topic, and also kind of rewarding in terms of development.

Of course other demands can be formulated too, but these then need to 
come with well defined descriptions (or mockup examples).

Hans

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

Re: graphics

[Alan Braslau]

On Tue, 4 Dec 2018 18:03:14 +0100
Hans Hagen <j.hagen@xs4all.nl> wrote:

> Hi,
> 
> As most mechanism are reasonable okay now we can look into what
> future versions of ConteXt should provide in terms of functionality.
> The (luatex) engine is also more of less finished or at least stable
> in terms of functionality.
> 
> One possible area of further development is graphics so I'd like to
> know if there are (reasonable) demands for more graphics support
> using metapost. Alan and I are on-and-off working on some extensions
> and one of the things we discuss is visualization of data. The
> question is of course what should be done in the lua/mp/tex
> combination and what externally but the combination has some
> advantages. There has been presentations and discussions at the last
> meeting and graphics is always a nice topic, and also kind of
> rewarding in terms of development.
> 
> Of course other demands can be formulated too, but these then need to 
> come with well defined descriptions (or mockup examples).

Hans is alluding to work that we are doing to explore the possibilities
of lua + MetaPost in the treatment and visualization of data,
efficiently, with the possibility of handling large quantities of data.
Lua does this particularly well.

My first exercise has been a complete rewrite of the John Hobby graph
macros. It was/is an exercise in recreating the functionality "from
scratch", trying to use lua effectively when needed. The code and
approach is entirely new. My use case was the analysis of a large set
of data - entirely ridiculous for graphical display but containing
"outliers" or instances that are significant, and it works! I am
trying to generalize, and am doing this in my "free time".

So the aim is two-fold:

1) to efficiently handle large datasets through the use of lua

2) to generalize the notion of user data space from the
two-dimensional drawing space of MetaPost (and the represented page),
and affine transformations of this 2D space to other coordinate
systems and dimensions. We are not thinking about 3D rendering or
raytracing, but rather simple projections and other transformations
such as polar coordinates. (Of course, log scales, for example are a
"simple" non-linear transformation.) 

I guess that Hans would like to expand the discussion to the future of
graphics in general, inviting input from everybody.

Alan
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Re: graphics

[Taco Hoekwater]

> On 4 Dec 2018, at 19:54, Alan Braslau <braslau.list@comcast.net> wrote:
> 
> 2) to generalize the notion of user data space from the
> two-dimensional drawing space of MetaPost (and the represented page),
> and affine transformations of this 2D space to other coordinate
> systems and dimensions. We are not thinking about 3D rendering or
> raytracing, but rather simple projections and other transformations
> such as polar coordinates. (Of course, log scales, for example are a
> "simple" non-linear transformation.) 

On this note: I would like to have an ‘official’ way to map 3D coordinates
to 2D coordinates with for a camera position with an orthogonal window.

Not the most complicated thing in the world, but it would be nice if
metafun had an ‘official’ way of setting up a scene.

Best wishes,
Taco



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Re: graphics

[Hans Hagen]

On 12/5/2018 10:02 AM, Taco Hoekwater wrote:
> 
> 
>> On 4 Dec 2018, at 19:54, Alan Braslau <braslau.list@comcast.net> wrote:
>>
>> 2) to generalize the notion of user data space from the
>> two-dimensional drawing space of MetaPost (and the represented page),
>> and affine transformations of this 2D space to other coordinate
>> systems and dimensions. We are not thinking about 3D rendering or
>> raytracing, but rather simple projections and other transformations
>> such as polar coordinates. (Of course, log scales, for example are a
>> "simple" non-linear transformation.)
> 
> On this note: I would like to have an ‘official’ way to map 3D coordinates
> to 2D coordinates with for a camera position with an orthogonal window.
> 
> Not the most complicated thing in the world, but it would be nice if
> metafun had an ‘official’ way of setting up a scene.
sounds like a challenge for our meta-math-magician Alan

Hans

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

Re: graphics

[Alan Braslau]

On Wed, 5 Dec 2018 13:59:35 +0100
Hans Hagen <j.hagen@xs4all.nl> wrote:

> > On this note: I would like to have an ‘official’ way to map 3D
> > coordinates to 2D coordinates with for a camera position with an
> > orthogonal window.
> > 
> > Not the most complicated thing in the world, but it would be nice if
> > metafun had an ‘official’ way of setting up a scene.  
> sounds like a challenge for our meta-math-magician Alan

Not a particularly hard problem (well known) but then one will want
hidden line removal, (partial) transparency, shading, ... and whereas
this is possible, it becomes complicated (and one will then want
animation).

For now, in my simple use of 3D to create diagrams, not any attempt to
make phluffy* images, I am quite content with a simple "caviler"
projection (infinite view position).

Alan

*Tufte's phluff!
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Re: graphics

[Procházka Lukáš Ing.]

Hello,

would it be possible to provide some samples finally?

That would be very handy especially for those who are used to create plots via "several clicks on Excel ribbon".

Personally, I am interested in 2D plots to be created loading (an) external data file(s) (text files formed into tables with some headers and comments marked by a letter in the beginning of the line), often altered by Lua somehow (e.g. trimming "bad" values).
I am used to use tickz/pgfplots for this purpose; use of pgfplots is (probably) very powerful but one has to study a lot of pages to create a simple plot followed by many try-and-see.
Also, support for showing extremal values (local extremes) in 2d plots is something handy.

"My" typical 2d plot looks:

     A
     |
30  |     24.1                         <- local extreme
     |     +
20  |  --- ---   15.6                 <- local extreme
     |/         \  +
10  |           -- ---
     |
     +----------------------------------------->
     10.     20.      30.      40.

Best regards,

Lukas


On Tue, 04 Dec 2018 19:54:54 +0100, Alan Braslau <braslau.list@comcast.net> wrote:

> On Tue, 4 Dec 2018 18:03:14 +0100
> Hans Hagen <j.hagen@xs4all.nl> wrote:
>
>> Hi,
>>
>> As most mechanism are reasonable okay now we can look into what
>> future versions of ConteXt should provide in terms of functionality.
>> The (luatex) engine is also more of less finished or at least stable
>> in terms of functionality.
>>
>> One possible area of further development is graphics so I'd like to
>> know if there are (reasonable) demands for more graphics support
>> using metapost. Alan and I are on-and-off working on some extensions
>> and one of the things we discuss is visualization of data. The
>> question is of course what should be done in the lua/mp/tex
>> combination and what externally but the combination has some
>> advantages. There has been presentations and discussions at the last
>> meeting and graphics is always a nice topic, and also kind of
>> rewarding in terms of development.
>>
>> Of course other demands can be formulated too, but these then need to
>> come with well defined descriptions (or mockup examples).
>
> Hans is alluding to work that we are doing to explore the possibilities
> of lua + MetaPost in the treatment and visualization of data,
> efficiently, with the possibility of handling large quantities of data.
> Lua does this particularly well.
>
> My first exercise has been a complete rewrite of the John Hobby graph
> macros. It was/is an exercise in recreating the functionality "from
> scratch", trying to use lua effectively when needed. The code and
> approach is entirely new. My use case was the analysis of a large set
> of data - entirely ridiculous for graphical display but containing
> "outliers" or instances that are significant, and it works! I am
> trying to generalize, and am doing this in my "free time".
>
> So the aim is two-fold:
>
> 1) to efficiently handle large datasets through the use of lua
>
> 2) to generalize the notion of user data space from the
> two-dimensional drawing space of MetaPost (and the represented page),
> and affine transformations of this 2D space to other coordinate
> systems and dimensions. We are not thinking about 3D rendering or
> raytracing, but rather simple projections and other transformations
> such as polar coordinates. (Of course, log scales, for example are a
> "simple" non-linear transformation.)
>
> I guess that Hans would like to expand the discussion to the future of
> graphics in general, inviting input from everybody.
>
> Alan


-- 
Ing. Lukáš Procházka | mailto:LPr@pontex.cz
Pontex s. r. o.      | mailto:pontex@pontex.cz | http://www.pontex.cz | IDDS: nrpt3sn | IČO: 40763439
Bezová 1658
147 14 Praha 4

Mob.: +420 702 033 396

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___________________________________________________________________________________

Re: graphics

[Henri Menke]

ConTeXt already comes with a full XML parser. SVG is XML. It would be
nice if it was possible to render some subset of SVG.

On 12/5/18 6:03 AM, Hans Hagen wrote:
> Hi,
> 
> As most mechanism are reasonable okay now we can look into what future
> versions of ConteXt should provide in terms of functionality. The
> (luatex) engine is also more of less finished or at least stable in
> terms of functionality.
> 
> One possible area of further development is graphics so I'd like to know
> if there are (reasonable) demands for more graphics support using
> metapost. Alan and I are on-and-off working on some extensions and one
> of the things we discuss is visualization of data. The question is of
> course what should be done in the lua/mp/tex combination and what
> externally but the combination has some advantages. There has been
> presentations and discussions at the last meeting and graphics is always
> a nice topic, and also kind of rewarding in terms of development.
> 
> Of course other demands can be formulated too, but these then need to
> come with well defined descriptions (or mockup examples).
> 
> Hans
> 
> -----------------------------------------------------------------
>                                           Hans Hagen | PRAGMA ADE
>               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
> ___________________________________________________________________________________
> 
> 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://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________

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Re: graphics

[luigi scarso]

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On Wed, Dec 5, 2018 at 10:15 AM Henri Menke <henrimenke@gmail.com> wrote:

> ConTeXt already comes with a full XML parser. SVG is XML. It would be
> nice if it was possible to render some subset of SVG.
>
In the mean time, I think we should also consider
 Headless Chromium for SVG -> PDF (with --print-to-pdf )
(together with inkscape)
-- 
luigi

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Re: graphics

[Hans Hagen]

On 12/5/2018 10:14 AM, Henri Menke wrote:
> ConTeXt already comes with a full XML parser. SVG is XML. It would be
> nice if it was possible to render some subset of SVG.
So what subset? ... Doing some shapes etc is doable but doing all is 
over the top

Hans


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

Re: graphics

[luigi scarso]

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On Wed, Dec 5, 2018 at 1:37 PM Hans Hagen <j.hagen@xs4all.nl> wrote:

> On 12/5/2018 10:14 AM, Henri Menke wrote:
> > ConTeXt already comes with a full XML parser. SVG is XML. It would be
> > nice if it was possible to render some subset of SVG.
> So what subset? ... Doing some shapes etc is doable but doing all is
> over the top
>
and of course some <something> will never be enough... never ending story.
The sad story with svg is that is an all-or-nothing thing  .

-- 
luigi

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___________________________________________________________________________________

Re: graphics

[Mikael P. Sundqvist]

On Tue, Dec 4, 2018 at 6:03 PM Hans Hagen <j.hagen@xs4all.nl> wrote:
>
> Hi,
>
> As most mechanism are reasonable okay now we can look into what future
> versions of ConteXt should provide in terms of functionality. The
> (luatex) engine is also more of less finished or at least stable in
> terms of functionality.
>
> One possible area of further development is graphics so I'd like to know
> if there are (reasonable) demands for more graphics support using
> metapost. Alan and I are on-and-off working on some extensions and one
> of the things we discuss is visualization of data. The question is of
> course what should be done in the lua/mp/tex combination and what
> externally but the combination has some advantages. There has been
> presentations and discussions at the last meeting and graphics is always
> a nice topic, and also kind of rewarding in terms of development.
>
> Of course other demands can be formulated too, but these then need to
> come with well defined descriptions (or mockup examples).
>
> Hans
>
> -----------------------------------------------------------------
>                                            Hans Hagen | PRAGMA ADE
>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
> ___________________________________________________________________________________
> 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://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________

Hi,

I don't know if what I describe below is along the lines you ask for,
but here comes two wishes:

1) Full support for drawing implicit curve plots. For some curves,
like a lemniscate
(https://en.wikipedia.org/wiki/Lemniscate_of_Bernoulli) one can easily
succeed by using a parametrisation, but sometimes one end up with
equations and to find a parametrisation might be difficult (not to say
impossible). I asked about this a while ago and got a simple solution
working for that curve, but I think a general working solution would
be neat. I think the bernoulli lemniscate could be a good test curve,
since it intersect itself.

2) Support for transforming images in a more general way. With the
zscaled, slanted, ... we are able to transform any object in an affine
way. It would be nice to be able to transform any object in a more
general way (i.e. by a mapping defined by the user). The example code
below shows what happens in the complex plane with a grid and a curve
when the mapping z to z^2 is applied. Perhaps I am missing something,
but I'm not able to apply this to a piece of text for example, or to
apply it directly to a picture. Instead, I have to loop over all
separate paths. I think the ideal would be to have a "ftransformed"
(or with some other name), and then just define a function (as fun in
the example below), and then be able to do "draw X ftransformed fun;",
where X is some(any?) general object. Is that doable?

/Mikael

%%% Example code
\starttext
\startMPpage[offset=3bp]
u:=3cm;

def fun(expr x,y) = (x**2-y**2,2*x*y) enddef;

def sq(expr kv,s) =
fun(xpart point 0 along kv,ypart point 0 along kv)
  for i=s step s until 1: -- fun(xpart point i along kv,ypart point i
along kv) endfor
enddef;

path rp;
rp = (0,-0.8)..(0.7,-0.2)..(0.7,0.6){dir
150}..(-0.7,0.4)..(-0.4,-0.5){dir 0}..cycle;


% Draw the original grid and the path
for i = -1 step 1/10 until 1+eps:
 for j = -1 step 1/10 until 1+eps:
  draw ((i,-1)--(i,1)) scaled u;
  draw ((-1,j)--(1,j)) scaled u;
 endfor;
endfor;

draw rp scaled u withcolor darkred withpen pencircle scaled 2bp;

% Draw the grid and curve after map z->z^2
draw image(
for i = -1 step 1/10 until 1+eps:
 for j = 0 step 1/10 until 1+eps:
  draw (sq(((i,0)--(i,1)),1/100)) scaled u;
  draw (sq(((-1,j)--(1,j)),1/100)) scaled u;
 endfor;
endfor;
draw (sq(rp,1/100)) scaled u withcolor darkred withpen pencircle scaled 2bp;
) xshifted 2.5u;

\stopMPpage
\stoptext
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Re: graphics

[luigi scarso]

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On Fri, Dec 7, 2018 at 9:06 AM Mikael P. Sundqvist <mickep@gmail.com> wrote:

> On Tue, Dec 4, 2018 at 6:03 PM Hans Hagen <j.hagen@xs4all.nl> wrote:
> >
> > Hi,
> >
> > As most mechanism are reasonable okay now we can look into what future
> > versions of ConteXt should provide in terms of functionality. The
> > (luatex) engine is also more of less finished or at least stable in
> > terms of functionality.
> >
> > One possible area of further development is graphics so I'd like to know
> > if there are (reasonable) demands for more graphics support using
> > metapost. Alan and I are on-and-off working on some extensions and one
> > of the things we discuss is visualization of data. The question is of
> > course what should be done in the lua/mp/tex combination and what
> > externally but the combination has some advantages. There has been
> > presentations and discussions at the last meeting and graphics is always
> > a nice topic, and also kind of rewarding in terms of development.
> >
> > Of course other demands can be formulated too, but these then need to
> > come with well defined descriptions (or mockup examples).
> >
> > Hans
> >
> > -----------------------------------------------------------------
> >                                            Hans Hagen | PRAGMA ADE
> >                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> >         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> > -----------------------------------------------------------------
> >
> ___________________________________________________________________________________
> > 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://context.aanhet.net
> > archive  : https://bitbucket.org/phg/context-mirror/commits/
> > wiki     : http://contextgarden.net
> >
> ___________________________________________________________________________________
>
> Hi,
>
> I don't know if what I describe below is along the lines you ask for,
> but here comes two wishes:
>
> 1) Full support for drawing implicit curve plots. For some curves,
> like a lemniscate
> (https://en.wikipedia.org/wiki/Lemniscate_of_Bernoulli) one can easily
> succeed by using a parametrisation, but sometimes one end up with
> equations and to find a parametrisation might be difficult (not to say
> impossible).

sure, see  eg
https://math.stackexchange.com/questions/904782/is-there-a-general-way-to-parameterize-all-implicit-functions


-- 
luigi

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Re: graphics

[Alan Braslau]

On Fri, 7 Dec 2018 09:06:03 +0100
"Mikael P. Sundqvist" <mickep@gmail.com> wrote:

> 2) Support for transforming images in a more general way. With the
> zscaled, slanted, ... we are able to transform any object in an affine
> way. It would be nice to be able to transform any object in a more
> general way (i.e. by a mapping defined by the user). The example code
> below shows what happens in the complex plane with a grid and a curve
> when the mapping z to z^2 is applied.

I have generalized my rewrite of the MP graph macros to handle any
arbitrary mapping from data space to drawing (2D) space. At present, I
have only considered the simple functions of log (and sqrt) scales as
well as polar coordinates (x,y) = f(theta,r) with f(theta,r) = (r sin
theta, r cos theta) as I have real use cases for these.

I also consider a simple 3D->2D mapping.

It would be very easy to transform z = a+ib to z^2 for example, as you
show, 


The approach transforms a picture, applying to all stroked and
filled paths, as well as to the *position* of text objects. I have not
looked into somehow transforming a bitmap image.

> Perhaps I am missing something,
> but I'm not able to apply this to a piece of text for example, or to
> apply it directly to a picture. Instead, I have to loop over all
> separate paths. I think the ideal would be to have a "ftransformed"
> (or with some other name), and then just define a function (as fun in
> the example below), and then be able to do "draw X ftransformed fun;",
> where X is some(any?) general object. Is that doable?

for i within pic :
  ...
endfor

So, yes, easy to write a primary (but I don't like the name
"ftransformed"). Using lua helpers can make this efficient.


Alan
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Re: graphics

[Mikael P. Sundqvist]

On Fri, Dec 7, 2018 at 4:15 PM Alan Braslau <braslau.list@comcast.net> wrote:
>
> On Fri, 7 Dec 2018 09:06:03 +0100
> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:
>
> > 2) Support for transforming images in a more general way. With the
> > zscaled, slanted, ... we are able to transform any object in an affine
> > way. It would be nice to be able to transform any object in a more
> > general way (i.e. by a mapping defined by the user). The example code
> > below shows what happens in the complex plane with a grid and a curve
> > when the mapping z to z^2 is applied.
>
> I have generalized my rewrite of the MP graph macros to handle any
> arbitrary mapping from data space to drawing (2D) space. At present, I
> have only considered the simple functions of log (and sqrt) scales as
> well as polar coordinates (x,y) = f(theta,r) with f(theta,r) = (r sin
> theta, r cos theta) as I have real use cases for these.

Sounds interesting. Do you have any "test document" to show the work
in progress?

>
> I also consider a simple 3D->2D mapping.

That sounds awesome!! The time working with colors as 3D might come to
an end! :)

>
> It would be very easy to transform z = a+ib to z^2 for example, as you
> show,
>
>
> The approach transforms a picture, applying to all stroked and
> filled paths, as well as to the *position* of text objects. I have not
> looked into somehow transforming a bitmap image.

You emphasize "position". Does it mean it will not be possible to
transform the shape of the letter?

>
> > Perhaps I am missing something,
> > but I'm not able to apply this to a piece of text for example, or to
> > apply it directly to a picture. Instead, I have to loop over all
> > separate paths. I think the ideal would be to have a "ftransformed"
> > (or with some other name), and then just define a function (as fun in
> > the example below), and then be able to do "draw X ftransformed fun;",
> > where X is some(any?) general object. Is that doable?
>
> for i within pic :
>   ...
> endfor
>
> So, yes, easy to write a primary (but I don't like the name
> "ftransformed"). Using lua helpers can make this efficient.

OK, looping through the pic sounds like a good idea. The word
ftransformed was made up while writing the email, and I agree it is
not good (perhaps "mapped" is better). I trust that you will come up
with something that fits well.

>
>
> Alan

Yet another wish:

3) It would be nice to be able to plot some special functions. I'm
thinking of the usual suspects, Airy, Bessel, Hypergeometric,
Laguerre, Legendre, ... Could it be that one could have support via
some lua library?

/Mikael
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Re: graphics

[Alan Braslau]

On Sat, 8 Dec 2018 09:31:46 +0100
"Mikael P. Sundqvist" <mickep@gmail.com> wrote:

> 3) It would be nice to be able to plot some special functions. I'm
> thinking of the usual suspects, Airy, Bessel, Hypergeometric,
> Laguerre, Legendre, ... Could it be that one could have support via
> some lua library?

I use ffi and libcerf (thank you Luigi!)
For example (lots of other functions are available):

\startluacode

ffi = require("ffi")
ffi.cdef[[
double j0(double x);
double j1(double x);
double jn(double x);
]]

cerf = ffi.load(ffi.os == "OSX" and "/opt/local/lib/libcerf.dylib" or "cerf")

\stopluacode

\startMPdefinitions {doublefun}

  vardef jzero primary x = scantokens(lua("mp.quoted( ffi.C.j0(" & decimal x & "))")) enddef ;
  vardef jone  primary x = scantokens(lua("mp.quoted( ffi.C.j1(" & decimal x & "))")) enddef ;
  vardef jn    primary x = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal x & "))")) enddef ;

\stopMPdefinitions
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Re: graphics

[Mikael P. Sundqvist]

On Sat, Dec 8, 2018 at 4:15 PM Alan Braslau <braslau.list@comcast.net> wrote:
>
> On Sat, 8 Dec 2018 09:31:46 +0100
> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:
>
> > 3) It would be nice to be able to plot some special functions. I'm
> > thinking of the usual suspects, Airy, Bessel, Hypergeometric,
> > Laguerre, Legendre, ... Could it be that one could have support via
> > some lua library?
>
> I use ffi and libcerf (thank you Luigi!)
> For example (lots of other functions are available):
>
> \startluacode
>
> ffi = require("ffi")
> ffi.cdef[[
> double j0(double x);
> double j1(double x);
> double jn(double x);
> ]]
>
> cerf = ffi.load(ffi.os == "OSX" and "/opt/local/lib/libcerf.dylib" or "cerf")
>
> \stopluacode
>
> \startMPdefinitions {doublefun}
>
>   vardef jzero primary x = scantokens(lua("mp.quoted( ffi.C.j0(" & decimal x & "))")) enddef ;
>   vardef jone  primary x = scantokens(lua("mp.quoted( ffi.C.j1(" & decimal x & "))")) enddef ;
>   vardef jn    primary x = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal x & "))")) enddef ;
>
> \stopMPdefinitions

Thanks, Alan! That looks very promising. I could not make it work,
though, and I guess that is because I use linux and do not know what
to change for what. I installed libcerf but I assume something else is
missing. In any case, this is one of the things it would be nice to
have, at least as a module. I have no idea on how to realize that,
though.

/Mikael
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Re: graphics

[Alan Braslau]

On Wed, 12 Dec 2018 20:42:56 +0100
"Mikael P. Sundqvist" <mickep@gmail.com> wrote:
> 
> Thanks, Alan! That looks very promising. I could not make it work,
> though, and I guess that is because I use linux and do not know what
> to change for what. I installed libcerf but I assume something else is
> missing. In any case, this is one of the things it would be nice to
> have, at least as a module. I have no idea on how to realize that,
> though.
> 
> /Mikael

You likely also need to install libffi - I do not know what package
this is on your flavor of linux - Luigi is the ffi specialist!

Alan
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Re: graphics

[Henri Menke]

On 13/12/18 8:56 AM, Alan Braslau wrote:
> On Wed, 12 Dec 2018 20:42:56 +0100
> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:
>>
>> Thanks, Alan! That looks very promising. I could not make it work,
>> though, and I guess that is because I use linux and do not know what
>> to change for what. I installed libcerf but I assume something else is
>> missing. In any case, this is one of the things it would be nice to
>> have, at least as a module. I have no idea on how to realize that,
>> though.
>>
>> /Mikael
> 
> You likely also need to install libffi - I do not know what package
> this is on your flavor of linux - Luigi is the ffi specialist!

FFI is integrated in LuaTeX >= 1.03

In you example you load libcerf but you are not using it.  What you are
actually using are the Bessel function from the C Standard library.  GCC
includes them as a GNU extension.
https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
Your example also works if you remove libcerf (at least for me on Linux).

> 
> Alan
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
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> ___________________________________________________________________________________
> 

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Re: graphics

[Alan Braslau]

On Thu, 13 Dec 2018 09:02:05 +1300
Henri Menke <henrimenke@gmail.com> wrote:

> On 13/12/18 8:56 AM, Alan Braslau wrote:
> > On Wed, 12 Dec 2018 20:42:56 +0100
> > "Mikael P. Sundqvist" <mickep@gmail.com> wrote:  
> >>
> >> Thanks, Alan! That looks very promising. I could not make it work,
> >> though, and I guess that is because I use linux and do not know
> >> what to change for what. I installed libcerf but I assume
> >> something else is missing. In any case, this is one of the things
> >> it would be nice to have, at least as a module. I have no idea on
> >> how to realize that, though.
> >>
> >> /Mikael  
> > 
> > You likely also need to install libffi - I do not know what package
> > this is on your flavor of linux - Luigi is the ffi specialist!  
> 
> FFI is integrated in LuaTeX >= 1.03
> 
> In you example you load libcerf but you are not using it.  What you
> are actually using are the Bessel function from the C Standard
> library.  GCC includes them as a GNU extension.
> https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
> Your example also works if you remove libcerf (at least for me on
> Linux).

I had stripped-down my example, for in fact I use the voigt and error
functions from libcerf, and yes the Bessel functions from the standard
C math library. One should note, by the way, that the C math library is
more or less complete depending on the system, and not everyone uses
gcc nor gnu...

Alan
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Re: graphics

[Henri Menke]

On 13/12/18 9:12 AM, Alan Braslau wrote:
> On Thu, 13 Dec 2018 09:02:05 +1300
> Henri Menke <henrimenke@gmail.com> wrote:
> 
>> On 13/12/18 8:56 AM, Alan Braslau wrote:
>>> On Wed, 12 Dec 2018 20:42:56 +0100
>>> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:  
>>>>
>>>> Thanks, Alan! That looks very promising. I could not make it work,
>>>> though, and I guess that is because I use linux and do not know
>>>> what to change for what. I installed libcerf but I assume
>>>> something else is missing. In any case, this is one of the things
>>>> it would be nice to have, at least as a module. I have no idea on
>>>> how to realize that, though.
>>>>
>>>> /Mikael  
>>>
>>> You likely also need to install libffi - I do not know what package
>>> this is on your flavor of linux - Luigi is the ffi specialist!  
>>
>> FFI is integrated in LuaTeX >= 1.03
>>
>> In you example you load libcerf but you are not using it.  What you
>> are actually using are the Bessel function from the C Standard
>> library.  GCC includes them as a GNU extension.
>> https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
>> Your example also works if you remove libcerf (at least for me on
>> Linux).
> 
> I had stripped-down my example, for in fact I use the voigt and error
> functions from libcerf, and yes the Bessel functions from the standard
> C math library. One should note, by the way, that the C math library is
> more or less complete depending on the system, and not everyone uses
> gcc nor gnu...

Sorry, my mistake, the Bessel functions are not a GCC extension but
POSIX standard functions.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/j0.html
Since TeX Live is always built on a POSIX platform (MSYS2 on Windows),
you can expect j0 etc. to be available in LuaTeX.

> 
> Alan
> 

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Re: graphics

[Alan Braslau]

On Thu, 13 Dec 2018 10:03:40 +1300
Henri Menke <henrimenke@gmail.com> wrote:

> Sorry, my mistake, the Bessel functions are not a GCC extension but
> POSIX standard functions.
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/j0.html
> Since TeX Live is always built on a POSIX platform (MSYS2 on Windows),
> you can expect j0 etc. to be available in LuaTeX.

That is true for the Bessel functions, but not for some other "-lmath"
functions (such as the erf), so they may depend on the system.

Alan
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Re: graphics

[Henri Menke]

On 13/12/18 10:39 AM, Alan Braslau wrote:
> On Thu, 13 Dec 2018 10:03:40 +1300
> Henri Menke <henrimenke@gmail.com> wrote:
> 
>> Sorry, my mistake, the Bessel functions are not a GCC extension but
>> POSIX standard functions.
>> http://pubs.opengroup.org/onlinepubs/9699919799/functions/j0.html
>> Since TeX Live is always built on a POSIX platform (MSYS2 on Windows),
>> you can expect j0 etc. to be available in LuaTeX.
> 
> That is true for the Bessel functions, but not for some other "-lmath"
> functions (such as the erf), so they may depend on the system.

erf definitely does not depend on the system.  That is part of the C
Standard library.
https://en.cppreference.com/w/c/numeric/math/erf

But in general you are right.  The zoo of special functions in the
Standard library and POSIX is rather limited.  Personally I prefer using
the GNU Scientific library if I need special functions.
https://www.gnu.org/software/gsl/doc/html/index.html

Earlier this year I wrote a TUGboat article about using GSL with FFI in
LuaTeX.
https://tug.org/TUGboat/tb39-1/tb121menke-ffi.pdf
I also plan on submitting an abstract about that topic for TUG2019 in
Palo Alto.

> 
> Alan
> 

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Re: graphics

[Mikael P. Sundqvist]

On Wed, Dec 12, 2018 at 9:02 PM Henri Menke <henrimenke@gmail.com> wrote:
>
> On 13/12/18 8:56 AM, Alan Braslau wrote:
> > On Wed, 12 Dec 2018 20:42:56 +0100
> > "Mikael P. Sundqvist" <mickep@gmail.com> wrote:
> >>
> >> Thanks, Alan! That looks very promising. I could not make it work,
> >> though, and I guess that is because I use linux and do not know what
> >> to change for what. I installed libcerf but I assume something else is
> >> missing. In any case, this is one of the things it would be nice to
> >> have, at least as a module. I have no idea on how to realize that,
> >> though.
> >>
> >> /Mikael
> >
> > You likely also need to install libffi - I do not know what package
> > this is on your flavor of linux - Luigi is the ffi specialist!
>
> FFI is integrated in LuaTeX >= 1.03
>
> In you example you load libcerf but you are not using it.  What you are
> actually using are the Bessel function from the C Standard library.  GCC
> includes them as a GNU extension.
> https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
> Your example also works if you remove libcerf (at least for me on Linux).
>

Thanks Henri! Indeed it worked now. The following example (just in
case someone else did not get what to change) compiles here, and shows
the expected graph. This is very good news!

\startluacode

ffi = require("ffi")
ffi.cdef[[
double j0(double x);
double j1(double x);
double jn(double x);
]]

\stopluacode

\startMPdefinitions{doublefun}
  vardef jzero primary x = scantokens(lua("mp.quoted( ffi.C.j0(" &
decimal x & "))")) enddef ;
  vardef jone  primary x = scantokens(lua("mp.quoted( ffi.C.j1(" &
decimal x & "))")) enddef ;
  vardef jn    primary x = scantokens(lua("mp.quoted( ffi.C.jn(" &
decimal x & "))")) enddef ;
\stopMPdefinitions


\starttext
\startMPpage[instance=doublefun]
draw function(1,"x","jone(x)",epsed(0),epsed(10),1/10) scaled 1cm;
\stopMPpage
\stoptext

/Mikael
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Re: graphics

[Otared Kavian]

Hi Mikael,

Thank you, as ell as Alan and Henri, for giving us a simple way to use Bessel functions, directly in ConTeXt.
However I have a question, which may show my total ignorance of the maths libraries ffi and consorts: how do you specify the value of the integr $n$ when you want to use $J_{n}(x)$?

Best regards: OK

> On 12 Dec 2018, at 21:13, Mikael P. Sundqvist <mickep@gmail.com> wrote:
> 
> On Wed, Dec 12, 2018 at 9:02 PM Henri Menke <henrimenke@gmail.com> wrote:
>> 
>> On 13/12/18 8:56 AM, Alan Braslau wrote:
>>> On Wed, 12 Dec 2018 20:42:56 +0100
>>> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:
>>>> 
>>>> Thanks, Alan! That looks very promising. I could not make it work,
>>>> though, and I guess that is because I use linux and do not know what
>>>> to change for what. I installed libcerf but I assume something else is
>>>> missing. In any case, this is one of the things it would be nice to
>>>> have, at least as a module. I have no idea on how to realize that,
>>>> though.
>>>> 
>>>> /Mikael
>>> 
>>> You likely also need to install libffi - I do not know what package
>>> this is on your flavor of linux - Luigi is the ffi specialist!
>> 
>> FFI is integrated in LuaTeX >= 1.03
>> 
>> In you example you load libcerf but you are not using it.  What you are
>> actually using are the Bessel function from the C Standard library.  GCC
>> includes them as a GNU extension.
>> https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
>> Your example also works if you remove libcerf (at least for me on Linux).
>> 
> 
> Thanks Henri! Indeed it worked now. The following example (just in
> case someone else did not get what to change) compiles here, and shows
> the expected graph. This is very good news!
> 
> \startluacode
> 
> ffi = require("ffi")
> ffi.cdef[[
> double j0(double x);
> double j1(double x);
> double jn(double x);
> ]]
> 
> \stopluacode
> 
> \startMPdefinitions{doublefun}
>  vardef jzero primary x = scantokens(lua("mp.quoted( ffi.C.j0(" &
> decimal x & "))")) enddef ;
>  vardef jone  primary x = scantokens(lua("mp.quoted( ffi.C.j1(" &
> decimal x & "))")) enddef ;
>  vardef jn    primary x = scantokens(lua("mp.quoted( ffi.C.jn(" &
> decimal x & "))")) enddef ;
> \stopMPdefinitions
> 
> 
> \starttext
> \startMPpage[instance=doublefun]
> draw function(1,"x","jone(x)",epsed(0),epsed(10),1/10) scaled 1cm;
> \stopMPpage
> \stoptext
> 
> /Mikael
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
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Re: graphics

[Alan Braslau]

Of course, it is:

double jn(int n,double x);

and

vardef jn(expr n, x) = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal n & "," & decimal x & "))")) enddef ;

Alan

(shows that I have yet to use jn ;-)


On Thu, 13 Dec 2018 14:32:39 +0100
Otared Kavian <otared@gmail.com> wrote:

> Hi Mikael,
> 
> Thank you, as ell as Alan and Henri, for giving us a simple way to use Bessel functions, directly in ConTeXt.
> However I have a question, which may show my total ignorance of the maths libraries ffi and consorts: how do you specify the value of the integr $n$ when you want to use $J_{n}(x)$?
> 
> Best regards: OK
> 
> > On 12 Dec 2018, at 21:13, Mikael P. Sundqvist <mickep@gmail.com> wrote:
> > 
> > On Wed, Dec 12, 2018 at 9:02 PM Henri Menke <henrimenke@gmail.com> wrote:  
> >> 
> >> On 13/12/18 8:56 AM, Alan Braslau wrote:  
> >>> On Wed, 12 Dec 2018 20:42:56 +0100
> >>> "Mikael P. Sundqvist" <mickep@gmail.com> wrote:  
> >>>> 
> >>>> Thanks, Alan! That looks very promising. I could not make it work,
> >>>> though, and I guess that is because I use linux and do not know what
> >>>> to change for what. I installed libcerf but I assume something else is
> >>>> missing. In any case, this is one of the things it would be nice to
> >>>> have, at least as a module. I have no idea on how to realize that,
> >>>> though.
> >>>> 
> >>>> /Mikael  
> >>> 
> >>> You likely also need to install libffi - I do not know what package
> >>> this is on your flavor of linux - Luigi is the ffi specialist!  
> >> 
> >> FFI is integrated in LuaTeX >= 1.03
> >> 
> >> In you example you load libcerf but you are not using it.  What you are
> >> actually using are the Bessel function from the C Standard library.  GCC
> >> includes them as a GNU extension.
> >> https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-j0
> >> Your example also works if you remove libcerf (at least for me on Linux).
> >>   
> > 
> > Thanks Henri! Indeed it worked now. The following example (just in
> > case someone else did not get what to change) compiles here, and shows
> > the expected graph. This is very good news!
> > 
> > \startluacode
> > 
> > ffi = require("ffi")
> > ffi.cdef[[
> > double j0(double x);
> > double j1(double x);
> > double jn(double x);
> > ]]
> > 
> > \stopluacode
> > 
> > \startMPdefinitions{doublefun}
> >  vardef jzero primary x = scantokens(lua("mp.quoted( ffi.C.j0(" &
> > decimal x & "))")) enddef ;
> >  vardef jone  primary x = scantokens(lua("mp.quoted( ffi.C.j1(" &
> > decimal x & "))")) enddef ;
> >  vardef jn    primary x = scantokens(lua("mp.quoted( ffi.C.jn(" &
> > decimal x & "))")) enddef ;
> > \stopMPdefinitions
> > 
> > 
> > \starttext
> > \startMPpage[instance=doublefun]
> > draw function(1,"x","jone(x)",epsed(0),epsed(10),1/10) scaled 1cm;
> > \stopMPpage
> > \stoptext
> > 
> > /Mikael
> > ___________________________________________________________________________________
> > 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://context.aanhet.net
> > archive  : https://bitbucket.org/phg/context-mirror/commits/
> > wiki     : http://contextgarden.net
> > ___________________________________________________________________________________  
> 
> ___________________________________________________________________________________
> 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: graphics

[luigi scarso]

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On Thu, Dec 13, 2018 at 4:45 PM Alan Braslau <braslau.list@comcast.net>
wrote:

> Of course, it is:
>
> double jn(int n,double x);
>
> and
>
> vardef jn(expr n, x) = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal n &
> "," & decimal x & "))")) enddef ;
>
> Alan
>
> (shows that I have yet to use jn ;-)
>

I often use this as reference
source/texk/web2c/luatexdir/luaffi/test.lua

-- 
luigi

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Re: graphics

[Henri Menke]

On 14/12/18 5:07 AM, luigi scarso wrote:
> On Thu, Dec 13, 2018 at 4:45 PM Alan Braslau <braslau.list@comcast.net>
> wrote:
> 
>> Of course, it is:
>>
>> double jn(int n,double x);
>>
>> and
>>
>> vardef jn(expr n, x) = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal n &
>> "," & decimal x & "))")) enddef ;
>>
>> Alan
>>
>> (shows that I have yet to use jn ;-)
>>
> 
> I often use this as reference
> source/texk/web2c/luatexdir/luaffi/test.lua

I have some Gists on GitHub using the FFI.

Binding interpreters of other scripting languages (so far Python, R,
Guile, and Lua):
https://gist.github.com/hmenke/2d57a3aa1d3d59a265f935dd4b384c36

Rendering SVG to PDF using Cairo and rsvg2:
https://gist.github.com/hmenke/9facc3fe5ede9ed46c1838a919f7376f#file-svg-to-pdf-lua

---

Some of the code on GitHub was inspired by answers of mine on the
StackExchange network.  Here is a collection of answers using FFI.  All
the answers from TeX Stack Exchange use LaTeX.  ConTeXt is not so
popular there.

How to implement X11 code for LuaJIT's FFI?
https://stackoverflow.com/a/53689893

How to plot a function in integral form with TikZ?
https://tex.stackexchange.com/a/403797
https://tex.stackexchange.com/a/403794

Erf function in LaTeX
https://tex.stackexchange.com/a/407087

Plot a factorial function
https://tex.stackexchange.com/a/371899

Plot bessel functions
https://tex.stackexchange.com/a/368692
https://tex.stackexchange.com/a/456772
https://tex.stackexchange.com/a/160749

(Lua) LaTeX & HeVeA with partly generated things
https://tex.stackexchange.com/a/429994

How to include SVG diagrams in LaTeX?
https://tex.stackexchange.com/a/408014

> 
> 
> ___________________________________________________________________________________
> 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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> ___________________________________________________________________________________
> 

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Re: graphics

[Mathias Schickel]

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Hi Hans and list members,

some time ago I asked Hans if he could implement a context analogon to the LaTeX asymptote package. This resulted in the context module asymptote.

It would be a nice addition (if this is not implemented yet) if the following functionality could be implemented in this module:

Writing a LaTeX file like the one attached using the asymptote package LaTeX and asymptote produce a pdf that contains a rendered version of the asymptote graphic and an interactive version of it as well. Both are embedded in the pdf file. The usually visible rendered pdf version can be made active (using Adobe Acrobat) if one clicks it – then the embedded interactive version gets visible and can be manipulated by the reader.

The LaTeX user does not need to specify anything, all is simply done by the asymptote package.

Could something like that be possible in ConTeXt, too? That would be really great! I suppose that asymptote is required to run twice to achieve that, one time to render the pdf version and a second time to render the prc file that contains the interactive version of the graphic. ConTeXt should then embed the interactive version of the graphic and the static one as well and should display the rendered pdf version until the reader clicks the static pdf version to make it active. Then the interactive graphic should get active and replace the static preview.

You can see the desired behaviour in the attached pdf output of the LaTeX file.

To compile the attached file using LaTeX and asymptote you can write in a terminal (after having navigated into the folder that contains the example file)

pdflatex latex-asymptote
asy latex-asymptote-*.asy
pdflatex latex-asymptote

Kind regards,
Mathias Schickel


 




> Am 04.12.2018 um 18:03 schrieb Hans Hagen <j.hagen@xs4all.nl>:
> 
> Hi,
> 
> As most mechanism are reasonable okay now we can look into what future versions of ConteXt should provide in terms of functionality. The (luatex) engine is also more of less finished or at least stable in terms of functionality.
> 
> One possible area of further development is graphics so I'd like to know if there are (reasonable) demands for more graphics support using metapost. Alan and I are on-and-off working on some extensions and one of the things we discuss is visualization of data. The question is of course what should be done in the lua/mp/tex combination and what externally but the combination has some advantages. There has been presentations and discussions at the last meeting and graphics is always a nice topic, and also kind of rewarding in terms of development.
> 
> Of course other demands can be formulated too, but these then need to come with well defined descriptions (or mockup examples).
> 
> Hans
> 
> -----------------------------------------------------------------
>                                          Hans Hagen | PRAGMA ADE
>              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>       tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
> ___________________________________________________________________________________
> 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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> ___________________________________________________________________________________


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Re: graphics

[Alan Braslau]

On Wed, 12 Dec 2018 14:51:47 +0100
Mathias Schickel <msch@fa.uni-tuebingen.de> wrote:

> You can see the desired behaviour in the attached pdf output of the
> LaTeX file.

No, one cannot, unless one has Adobe...

Alan
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