On 15/10/2007, Luke J Crook <[EMAIL PROTECTED]> wrote:
> Brad Beveridge writes:
>
> > Hi guys,
> > I recently wrote a small line graph plotting app using Lispbuilder,
> > SBCL and OS X.  Basically the app draws a little line graph every
> > frame that measures some input.  I was pretty astounded to find that
> > doing ~200 sdl-gfx-draw-line-* calls was taking about 2.5ms.
>
>
> Good astounded, or bad astounded? :)
>
> You probably already know that lispbuilder-sdl contains line drawing
> functions, so there is no real need to pull in sdl_gfx (unless you really
> need the extra speed).
It was bad astounded :)  I've recently changed jobs & I'm working for
a games company.  To run at 60FPS, you need to have all your drawing
done in around 16ms.  If I think about it a little harder though,
perhaps I shouldn't be quite so upset - the drawing is done purely in
software after all.
I was originally using sdl-gfx-draw-aa-line for a slightly nicer look,
and drawing from x0,y0,x1+1,y1 to get the line.  Interestingly I
noticed that drawing x0,y0,x0,y1 is significantly faster, I assume
that the line draw algorithm has a fast path for when (= x0 x1).

As a side note, the reason I'm doing this is so I can have a monitor
program displaying real time info on a running game.  It's just a side
project at the moment though :)

Cheers,
Brad
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