On 06/22/2017 01:21 AM, James Richters wrote:
putimage can be accelerated, although it would still have to do a memory copy.
Like this?
https://github.com/Zaaphod/ptcpas/compare/Zaaphod_Custom?expand=1#diff-fb31461e009ff29fda5c35c5115978b4
This is amazingly faster. I ran a test of just ptcgraph.putimage() in a loop,
putting the same image over and over 1000 times and timing it. The original
ptcgraph.putimage() took 18.017 seconds. After I applied this, the same loop
took 1.056 seconds. Quite an improvement! It's still nowhere near as fast
as just drawing stuff with ptcgraph directly, but for doing a memory copy of
the entire screen, it's very fast
Yes, that's a good start. That was exactly what I meant :)
I have an idea on how I could speed it up even further....
If I set up a second array with 1 bit per pixel, then (somehow) aggpas could set bits
in this array to 1 whenever it changed a corresponding bit. Now by analyzing the
'pixel changed' array one word at a time, (or maybe longword or qword at a time) I
could just skip over all the words that =0 and when I come across a word that
<> 0 I could do a binary search of that word to only change the pixels that
need to be changed. If very little on the screen has changed, this would be quite a
bit faster because the pixel changed array would be 1/16 the size of the full buffer.
The only way this would be of any benefit though is if aggpas set the bits in
the 'pixel changed' array while it was changing the pixels of the buffer,
because at that time it already has the array position and the fact that
something changed available. If I had to analyze the buffer separately and
create the 'pixels changed' array, it would take too long.
That sounds like a little bit of a special case - it'll work where
you're using putimage for a large area, that has very few pixels set.
Perhaps just reimplementing the general algorithm in inline asm, by
using SSE (or MMX) vector instructions would be the fastest, but maybe
it's not worth the pain and the pascal implementation is fast enough for
you. Just experiment and see what works best :)
Nikolay
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