On Apr 2, 2009, at 2:05 AM, MikeM wrote:
>
> Starting with your version, I got about a 2x improvement with the
> following:
>
> (defn check-bounds [x y]
> (let [f2 (float 2.0)
> f4 (float 4.0)]
> (loop [px (float x)
> py (float y)
> zx (float 0.0)
> zy (float 0.0)
> zx2 (float 0.0)
> zy2 (float 0.0)
> value (float 0)]
> (if (and (< value (*max-steps*)) (< (+ zx2 zy2) f4))
> (let [new-zy (float (+ (* (* f2 zx) zy) py))
> new-zx (float (+ (- zx2 zy2) px))
> new-zx2 (float (* new-zx new-zx))
> new-zy2 (float (* new-zy new-zy))]
> (recur px py new-zx new-zy new-zx2 new-zy2 (inc
> value)))
> (if (== value (*max-steps*)) 0 value)))))
>
> f2 and f4 didn't do much, most improvement seems to come from (* (* f2
> zx) zy) in place of (* f2 zx zy). Using the arity 2 multiply results
> in the multiply being inlined.
Building on your and Paul's improvements I simply wrapped (almost)
everything in a 'let' rather than using 'def' or Paul's cool macro
idea. I also pulled out a couple of divisions from draw-line. This
takes about 38% of the time of Paul's version:
(let [width (float 640)
height (float 640)
max-steps (float 32)
color-scale (float (quot 255 max-steps))
height-factor (/ 2.5 height)
width-factor (/ 2.5 width)]
(defn on-thread [#^Runnable f] (doto (new Thread f) (.start)))
(defn check-bounds [x y]
(let [f2 (float 2.0)
f4 (float 4.0)]
(loop [px (float x)
py (float y)
zx (float 0.0)
zy (float 0.0)
zx2 (float 0.0)
zy2 (float 0.0)
value (float 0)]
(if (and (< value max-steps) (< (+ zx2 zy2) f4))
(let [new-zy (float (+ (* (* f2 zx) zy) py))
new-zx (float (+ (- zx2 zy2) px))
new-zx2 (float (* new-zx new-zx))
new-zy2 (float (* new-zy new-zy))]
(recur px py new-zx new-zy new-zx2 new-zy2 (inc
value)))
(if (== value max-steps) 0 value)))))
(defn draw-line [#^Graphics g y]
(let [dy (- 1.25 (* y height-factor))]
(doseq [x (range 0 width)]
(let [dx (- (* x width-factor) 2.0)]
(let [value (check-bounds dx dy)]
(if (> value 0)
(doto g
(. setColor (Color. (* value color-scale)))
(. drawRect x y 0 0))))))))
(defn draw-lines
([buffer g] (draw-lines buffer g height))
([#^BufferStrategy buffer g y]
(doseq [y (range 0 y)]
(draw-line g y)
;(on-thread (draw-line g y))
(. buffer show))))
(defn draw [#^Canvas canvas]
(let [buffer (. canvas getBufferStrategy)
g (. buffer getDrawGraphics)]
(draw-lines buffer g)))
(defn main []
(let [panel (JPanel.)
canvas (Canvas.)
frame (JFrame. "Mandelbrot")]
(doto panel
(.setPreferredSize (Dimension. width height))
(.setLayout nil)
(.add canvas))
(doto frame
(.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE)
(.setBounds 0,0,width height)
(.setResizable false)
(.add panel)
(.setVisible true))
(doto canvas
(.setBounds 0,0,width height)
(.setBackground (Color/BLACK))
(.createBufferStrategy 2)
(.requestFocus))
(draw canvas))))
Aloha,
David Sletten
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