69 lines
1.4 KiB
Lua
69 lines
1.4 KiB
Lua
--PICTURE scene: Ellipse update-demo (anim)
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--Demonstrates 'interactive' features.
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--by Richard Fhager
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-- Copyright 2011 Richard Fhager
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--
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-- This program is free software; you can redistribute it and/or
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-- modify it under the terms of the GNU General Public License
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-- as published by the Free Software Foundation; version 2
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-- of the License. See <http://www.gnu.org/licenses/>
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--
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-- rot: Rotation in degrees
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-- stp: Step is # of line segments (more is "better")
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-- a & b are axis-radius
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function ellipse2(x,y,a,b,stp,rot,col)
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local n,m=math,rad,al,sa,ca,sb,cb,ox,oy,x1,y1,ast
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m = math; rad = m.pi/180; ast = rad * 360/stp;
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sb = m.sin(-rot * rad); cb = m.cos(-rot * rad)
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for n = 0, stp, 1 do
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ox = x1; oy = y1;
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sa = m.sin(ast*n) * b; ca = m.cos(ast*n) * a
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x1 = x + ca * cb - sa * sb
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y1 = y + ca * sb + sa * cb
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if (n > 0) then drawline(ox,oy,x1,y1,col); end
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end
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end
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--
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setpicturesize(300,300)
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setcolor(0,96,96,96)
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setcolor(1,255,255,128)
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r1 = 100
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r2 = 50
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rt = 0
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frames = 100
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while (1 < 2) do
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r1t = 10 + math.random() * 140
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r2t = 10 + math.random() * 140
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rtt = math.random() * 360
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for n = 0, frames-1, 1 do
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clearpicture(0)
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f2 = n / frames
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f1 = 1 - f2
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r1a = r1*f1 + r1t*f2
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r2a = r2*f1 + r2t*f2
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rta = rt*f1 + rtt*f2
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-- x, y, r1, r2, stp, rot, col
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ellipse2(150, 150, r1a, r2a, 50, rta, 1)
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statusmessage('press ESC to stop')
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updatescreen();if (waitbreak(0)==1) then return end
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end
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r1,r2,rt = r1a,r2a,rta
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end
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