[Gnash-dev] Re: Bitmap caches

[Udo Giacomozzi]

Hello strk,

Monday, October 2, 2006, 6:18:06 PM, you wrote:
s> Udo, another thing to think about is that IIRC, with the Flash
s> player version 8 a "cache as bitmap" function has been added
s> to the MovieClip class. This is exactly to move cache control
s> to the SWF developer.

s> I think the rationale is that cached characters are only
s> good if you know you'd be moving that character around often
s> w/out matrix transforms. If youre character is going to
s> be transormed a lot the cache does only degrade performance.

s> Does this sound ?


I was thinking of some sort of smart cache. The cache manager could
just keep track of possible cache hits before the shape is really
cached. Say, if a certain character state was required about 3-5 times
it will create a bitmap cache the fifth time and use that from that
moment on.

It has some downsides (memory usage, maybe not smooth playback in
extreme cases) but would be a huge performance gain in some
situations. Think of a complex background where a small sprite moves
over. Normally the background would have to be rendered again and
again even if it does not change. Caching the background would allow
very fast movement of the simple sprite (starting from the fifth
frame, when the cache is activated).

I don't think Flash does something like this, but I often wished it
would do so. Application-type flash movies would benefit from this
method. :)

However, this is just an idea, and it's already difficult enough to
think about the renderer redesign.

The "cache as bitmap" would just be a hint to the the cache manager, I
see no problem there.

Udo