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