Re: [Gnash-dev] Performance drop

[Eric Hughes]

At 11:00 AM 5/29/2007, Udo Giacomozzi wrote:
> I compared the code for character.cpp and matrix.cpp but could not
> find any relevant part that could cause this slow-down.

I haven't delved at all into it in any depth, but when I looked at the 
matrix code last month I did notice one thing I was going to recommend: 
storing both canonical matrix parameters and the matrix itself and 
computing the matrix only when necessary.  In other words, treating the 
matrix values as a cache.  When matrix canonical values are assigned, all 
the trigonometric function are recomputed, which is going to be the most 
expensive operation of the lot.

Perhaps better: when assigning canonical values, check them against 
existing canonical values.  If the same, do nothing.  If different, update 
the value and invalidate the matrix values.  When performing a matrix 
operation, check validity first and recompute if necessary.

In the same vein, caching the sine and cosine of the canonical rotation 
value means that changing only the scale wouldn't incur any new 
trigonometric computation.  In such a case the multiplications would dominate.

I don't know enough about how the matrix computations fit within the 
overall control scheme of the player, but if they're in anything like an 
inner loop, caching these calculations should significantly improve 
performance.

Eric