draw & fill

draw & fill

[Peter Rolf]

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Hi all,

[maybe this is a bit off topic and you think that the Metapost mailing
list is the right place for such stuff. But I have quit this list quite
some time ago, as there was more spam than regular posts. Try to forgive
me... :D ]

After buying the 'Metafont' manual, I'm now playing around with some mp
macro programming. The problem in the attached example is, that the
'draw' variants of the [hv]line macro always work with a *fixed* pen
size of 1pt (and I can't figure out why). I'm clueless..

Greetings, Peter

[-- Attachment #2: draw_and_fill.tex --]
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\setupoutput[pdftex]
\setupcolors[state=start]

\starttext

\startMPinclusions
  % default unit
  u:= .5 ; % u:=1 works, u:=2 doesn't

  pen upen ;
  upen = makepen(unitsquare scaled u shifted -(.5u,.5u)) ;

  % width, height, shift-x, shift-y, color
  def fill_square(expr w,h,a,b,c)=
    fill unitsquare xyscaled(w*u,h*u)
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def fill_hline(expr w,a,b,c)=
    fill_square(w,u,a,b,c)
  enddef ;

  def fill_vline(expr h,a,b,c)=
    fill_square(u,h,a,b,c)
  enddef ;

  % the drawing macros always use a pen of 1pt ;
  % even with an extra defined pen
  def draw_hline(expr w,a,b,c)=
    draw (.5u,.5u)--(w*u-.5u,.5u) withpen upen
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def draw_vline(expr h,a,b,c)=
    draw (.5u,.5u)--(.5u,h*u-.5u) withpen pensquare scaled u
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def draw_frame(expr w,h,a,b,c)=
    draw (.5u,.5u)--(w*u-.5u,.5u)--(w*u-.5u,h*u-.5u)--(.5u,h*u-.5u)--cycle
    withpen pensquare scaled u
    shifted (a*u,b*u)
    withcolor c
  enddef ;

\stopMPinclusions

\startMPpage

  fill_hline(20,5,5,red) ;
  fill_vline(20,5,5,red) ;

  draw_vline(20,5,25,blue) ;
  draw_hline(20,25,5,blue) ;

  draw_frame(50,50,0,0,black) ;

\stopMPpage

\stoptext

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Re: draw & fill

[Taco Hoekwater]

Hi Peter,

>   def draw_vline(expr h,a,b,c)=
>     draw (.5u,.5u)--(.5u,h*u-.5u) withpen pensquare scaled u

That scales the whole draw statement, just like if you had said:

      draw (.5u,.5u)--(.5u,h*u-.5u) scaled u withpen pensquare

So you need to do it like this:

     draw (.5u,.5u)--(.5u,h*u-.5u) withpen (pensquare scaled u)

Cheers, Taco

Re: draw & fill

[Peter Rolf]

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Taco Hoekwater wrote:
> Hi Peter,
> 
>>   def draw_vline(expr h,a,b,c)=
>>     draw (.5u,.5u)--(.5u,h*u-.5u) withpen pensquare scaled u
> 
> That scales the whole draw statement, just like if you had said:
> 
>       draw (.5u,.5u)--(.5u,h*u-.5u) scaled u withpen pensquare
> 
> So you need to do it like this:
> 
>      draw (.5u,.5u)--(.5u,h*u-.5u) withpen (pensquare scaled u)
>
Hi Taco,

thanks for the answer. Sadly I doesn't work here; all drawn lines are
still fixed to 1pt. Even my own defined pen (upen) in draw_hline is
completely ignored.

Greetings, Peter


> Cheers, Taco
> _______________________________________________
> ntg-context mailing list
> ntg-context@ntg.nl
> http://www.ntg.nl/mailman/listinfo/ntg-context
> 
> 


[-- Attachment #2: draw_and_fill.tex --]
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\setupoutput[pdftex]
\setupcolors[state=start]

\starttext

\startMPinclusions
  % default unit
  u:= 2 ; % u:=1 works, u:=2 doesn't

  pen upen ;
  upen = makepen(unitsquare scaled u shifted -(.5u,.5u)) ;

  % width, height, shift-x, shift-y, color
  def fill_square(expr w,h,a,b,c)=
    fill unitsquare xyscaled(w*u,h*u)
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def fill_hline(expr w,a,b,c)=
    fill_square(w,u,a,b,c)
  enddef ;

  def fill_vline(expr h,a,b,c)=
    fill_square(u,h,a,b,c)
  enddef ;

  % the drawing macros always use a pen of 1pt ;
  % even with an extra defined pen
  def draw_hline(expr w,a,b,c)=
    draw (.5u,.5u)--(w*u-.5u,.5u) withpen upen
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def draw_vline(expr h,a,b,c)=
    draw (.5u,.5u)--(.5u,h*u-.5u) withpen (pensquare scaled u)
    shifted (a*u,b*u)
    withcolor c
  enddef ;

  def draw_frame(expr w,h,a,b,c)=
    draw (.5u,.5u)--(w*u-.5u,.5u)--(w*u-.5u,h*u-.5u)--(.5u,h*u-.5u)--cycle
    withpen (pensquare scaled u)
    shifted (a*u,b*u)
    withcolor c
  enddef ;

\stopMPinclusions

\startMPpage

  fill_hline(20,5,5,red) ;
  fill_vline(20,5,5,red) ;

  draw_vline(20,5,25,blue) ;
  draw_hline(20,25,5,blue) ;

  draw_frame(50,50,0,0,black) ;

\stopMPpage

\stoptext

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Re: draw & fill

[Taco Hoekwater]

Peter Rolf wrote:
> 
> Hi Taco,
> 
> thanks for the answer. Sadly I doesn't work here; all drawn lines are
> still fixed to 1pt. Even my own defined pen (upen) in draw_hline is
> completely ignored.

I was somewhat wrong before. The problem in your case is not the
grouping but that you are scaling *everything* by u.

Try this: set u back to 1, then add a second MPpage like this:

   \startMPpage
   u:= 2;
   fill_hline(20,5,5,red) ;
   fill_vline(20,5,5,red) ;

   draw_vline(20,5,25,blue) ;
   draw_hline(20,25,5,blue) ;

   draw_frame(50,50,0,0,black) ;
   \stopMPpage

It should be clear from the output pages what happens.

Greetings,
Taco

Re: draw & fill

[Peter Rolf]

Taco Hoekwater wrote:
> Peter Rolf wrote:
>> Hi Taco,
>>
>> thanks for the answer. Sadly I doesn't work here; all drawn lines are
>> still fixed to 1pt. Even my own defined pen (upen) in draw_hline is
>> completely ignored.
> 
> I was somewhat wrong before. The problem in your case is not the
> grouping but that you are scaling *everything* by u.
> 
> Try this: set u back to 1, then add a second MPpage like this:
> 
>    \startMPpage
>    u:= 2;
>    fill_hline(20,5,5,red) ;
>    fill_vline(20,5,5,red) ;
> 
>    draw_vline(20,5,25,blue) ;
>    draw_hline(20,25,5,blue) ;
> 
>    draw_frame(50,50,0,0,black) ;
>    \stopMPpage
> 
> It should be clear from the output pages what happens.
>
Many thanks Taco! Now I clearly see what happens :)

Greetings, Peter

> Greetings,
> Taco
> 
> _______________________________________________
> ntg-context mailing list
> ntg-context@ntg.nl
> http://www.ntg.nl/mailman/listinfo/ntg-context
> 
>