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Bitmap/Bézier curves/Cubic: Difference between revisions
add Ruby
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by_pair pts (fun p0 p1 -> line ~p0 ~p1);
;;</lang>
=={{header|Ruby}}==
{{trans|Tcl}}
<lang ruby>class Pixmap
def draw_bezier_curve(points, colour)
# ensure the points are increasing along the x-axis
points = points.sort_by {|p| [p.x, p.y]}
xmin = points[0].x
xmax = points[-1].x
increment = 2
prev = points[0]
((xmin + increment) .. xmax).step(increment) do |x|
t = 1.0 * (x - xmin) / (xmax - xmin)
p = Pixel[x, bezier(t, points).round]
draw_line(prev, p, colour)
prev = p
end
end
end
# the generalized n-degree Bezier summation
def bezier(t, points)
n = points.length - 1
points.each_with_index.inject(0.0) do |sum, (point, i)|
sum += n.choose(i) * (1-t)**(n - i) * t**i * point.y
end
end
class Fixnum
def choose(k)
self.factorial / (k.factorial * (self - k).factorial)
end
def factorial
(2 .. self).reduce(1, :*)
end
end
bitmap = Pixmap.new(400, 400)
points = [
Pixel[40,100], Pixel[100,350], Pixel[150,50],
Pixel[150,150], Pixel[350,250], Pixel[250,250]
]
points.each {|p| bitmap.draw_circle(p, 3, RGBColour::RED)}
bitmap.draw_bezier_curve(points, RGBColour::BLUE)</lang>
=={{header|Tcl}}==
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