60 lines
1.8 KiB
Factor
60 lines
1.8 KiB
Factor
! Copyright (c) 2012 Anonymous
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors arrays calendar colors.constants kernel
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locals math math.constants math.functions math.rectangles
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math.vectors opengl sequences system timers ui ui.gadgets ui.render ;
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IN: rosetta-code.animate-pendulum
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! http://rosettacode.org/wiki/Animate_a_pendulum
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! One good way of making an animation is by simulating a
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! physical system and illustrating the variables in that system
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! using a dynamically changing graphical display. The classic such
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! physical system is a simple gravity pendulum.
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! For this task, create a simple physical model of a pendulum
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! and animate it.
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CONSTANT: g 9.81
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CONSTANT: l 20
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CONSTANT: theta0 0.5
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: current-time ( -- time ) nano-count -9 10^ * ;
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: T0 ( -- T0 ) 2 pi l g / sqrt * * ;
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: omega0 ( -- omega0 ) 2 pi * T0 / ;
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: theta ( -- theta ) current-time omega0 * cos theta0 * ;
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: relative-xy ( theta l -- xy )
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[ [ sin ] [ cos ] bi ]
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[ [ * ] curry ] bi* bi@ 2array ;
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: theta-to-xy ( origin theta l -- xy ) relative-xy v+ ;
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TUPLE: pendulum-gadget < gadget alarm ;
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: O ( gadget -- origin ) rect-bounds [ drop ] [ first 2 / ] bi* 0 2array ;
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: window-l ( gadget -- l ) rect-bounds [ drop ] [ second ] bi* ;
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: gadget-xy ( gadget -- xy ) [ O ] [ drop theta ] [ window-l ] tri theta-to-xy ;
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M: pendulum-gadget draw-gadget*
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COLOR: black gl-color
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[ O ] [ gadget-xy ] bi gl-line ;
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M: pendulum-gadget graft* ( gadget -- )
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[ call-next-method ]
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[
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dup [ relayout-1 ] curry
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20 milliseconds every >>alarm drop
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] bi ;
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M: pendulum-gadget ungraft*
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[ alarm>> stop-timer ] [ call-next-method ] bi ;
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: <pendulum-gadget> ( -- gadget )
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pendulum-gadget new
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{ 500 500 } >>pref-dim ;
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MAIN-WINDOW: pendulum-main
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{ { title "pendulum" } }
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<pendulum-gadget> >>gadgets ;
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