To promote modularity and allow easy change to go either
way, or even allow a choice by parameter...
the direct draw commands should be outside the painting verb.
glclear ''
drawPendulum ANGLE
glpaint ''
> From: bill lam <bbill....@gmail.com>
>
> This is a version that doesn't require invalidate.
>
>
> NB.=================================================================
> require 'gl2 trig'
> coinsert 'jgl2'
>
> DT =: %30 NB. seconds
> ANGLE=: 0.25p1 NB. radians
> L =: 1 NB. metres
> G =: 9.80665 NB. ms_2
> VEL =: 0 NB. ms_1
>
> PEND=: noun define
> pc pend;pn "Pendulum";
> xywh 0 0 320 200;cc isi isigraph rightmove bottommove;
> pas 0 0;pcenter;
> rem form end;
> )
>
> pend_run =: verb def ' wd PEND,'';pshow;timer '',":DT * 1000 '
> pend_close =: verb def ' wd ''timer 0; pclose'' '
> NB. pend_isi_paint=: verb def ' drawPendulum ANGLE '
>
> sys_timer_z_=: verb define
> recalcAngle ''
> drawPendulum ANGLE
> NB. wd 'psel pend; setinvalid isi'
> )
>
> recalcAngle=: verb define
> accel=. - (G % L) * sin ANGLE
> VEL =: VEL + accel * DT
> ANGLE=: ANGLE + VEL * DT
> )
>
> drawPendulum=: verb define
> width=. {. glqwh''
> ps=. (-: width) , 40
> pe=. ps + 280 <....@* (cos , sin) 0.5p1 + y NB. adjust orientation
> glclear ''
> glbrush ''
> glrgb 91 91 91
> gllines ps , pe
> glellipse (,~ ps - -:) 40 15
> glellipse (,~ pe - -:) 20 20
> glrect 0 0 ,width, 40
> glpaint ''
> )
>
> pend_run'' NB. run animation
> NB.=================================================================
>
>
> --
> regards,
> ====================================================
> GPG key 1024D/4434BAB3 2008-08-24
> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
> ----------------------------------------------------------------------
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----------------------------------------------------------------------
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