Hi,
First, find the actual point along the curve of the wave you want, then you can
ask for the direction of the wave at that time, and its point:
\startuseMPgraphic{Waves}
numeric height,stops,yoffset;
stops := 10;
height := OverlayHeight/10;
path wave[]; % storing waves
draw (0,0)--(OverlayWidth,0)--(OverlayWidth,OverlayHeight) withcolor white
withpen pencircle scaled 0.01;
for j=1 upto 3:
definecolor [name="Sea", y=(j/20), c=2*(j/10), m=(j/20)];
yoffset := height/(j*2);
wave[j] := (0,0)--(0,yoffset)...
for i=1 upto stops:
(OverlayWidth*i/(stops+1), (yoffset) randomized (height/2)) ...
endfor
(OverlayWidth,yoffset);
fill ((0,0)--wave[j]--(OverlayWidth,0)--cycle) withcolor "Sea";
endfor;
xpos := OverlayWidth * RealPageNumber/NOfPages;
path ship;
ship := (0,10)---(70,10)...(60,0)---(10,0)...cycle;
pair itime, iangle, boatpos;
itime = (wave[3] intersectiontimes ((xpos,0)--(xpos,infinity)));
iangle = direction (xpart itime) of wave[3];
boatpos = (point (xpart itime) of wave[3]) shifted (-5,0); % shift to center
horizontally
fill ship xysized (10,5) shifted boatpos rotatedaround (boatpos, angle iangle)
withcolor red;
\stopuseMPgraph
> On 19 Jul 2023, at 12:32, Henning Hraban Ramm wrote:
>
> Hi,
> I’d like a presentation progress indicator that looks like a boat on waves –
> and if it works, it can also become a bike on hills or a mars rover on dunes.
> But my math skills are lacking.
>
> Below’s a mostly working draft.
>
> * I find the waves not yet very convincing. Would it make sense to use a
> randomized sinus? (How?)
>
> * The boat should sit on the middle wave and be rotated by the current slope.
> I know I need the “time” of the upper curve and get the 1st derivation, but
> how?
>
> """
> \setuppapersize[SW]
>
> \startuseMPgraphic{Waves}
> numeric height,stops,yoffset;
> stops := 10;
> height := OverlayHeight/10;
> path wave;
>
> draw (0,0)--(OverlayWidth,0)--(OverlayWidth,OverlayHeight) withcolor white
> withpen pencircle scaled 0.01;
>
> for j=1 upto 3:
> definecolor [name="Sea", y=(j/20), c=2*(j/10), m=(j/20)];
> yoffset := height/(j*2);
> wave := (0,0)--(0,yoffset)...
> for i=1 upto stops:
>(OverlayWidth*i/(stops+1), (yoffset) randomized (height/2)) ...
> endfor
> (OverlayWidth,yoffset)--(OverlayWidth,0)--cycle;
> fill wave withcolor "Sea";
> endfor;
>
> pair pos;
> pos := (OverlayWidth * RealPageNumber/NOfPages, height/2 randomized 2);
> path ship;
> ship := (0,10)---(70,10)...(60,0)---(10,0)...cycle;
>
> fill ship xysized (10,5) shifted pos rotatedaround (pos, 15) withcolor red;
> \stopuseMPgraphic
>
> \defineoverlay[Waves][\useMPgraphic{Waves}]
>
> \setupbackgrounds[state=repeat]
> \setupbackgrounds[page][background={Waves}]
>
> \starttext
>
> \dorecurse{10}{\recurselevel\page}
>
> \stoptext
> """
>
> Hraban
> ___
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> Wiki!
>
> maillist : ntg-context@ntg.nl /
> https://www.ntg.nl/mailman/listinfo/ntg-context
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> ___
—
Taco Hoekwater E: t...@bittext.nl
genderfluid (all pronouns)
___
If your question is of interest to others as well, please add an entry to the
Wiki!
maillist : ntg-context@ntg.nl / https://www.ntg.nl/mailman/listinfo/ntg-context
webpage : https://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : https://contextgarden.net
___
