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Oswald
Registered: Apr 2002
Posts: 5086 |
Sorting
are sorters really so slow in games? :) I have made my unrolled version for my theoretical game (;), and it takes 132 rlines to sort 32 numbers o_O worst case is ~200 lines. tho when its the case of 4 numbers have to be swapped only it does the job in ~10 lines. wastes a lot of memory but I like it :) |
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doynax
Account closed
Registered: Oct 2004
Posts: 212 |
Quote: doynax, whoaw, now thats a massive amount of sprites :) \o/ how do you make the d800 copy, and where ? :) btw what bugs me about bucket sort is how to deal with the random order in the multiplexer, also rejecting 9th sprites seems to be messy :P
The d800 copy is double buffered and evenly distributed across 16 frames, so it really doesn't take much raster time at all ;)
As for the bucket sort I don't quite see what you mean. The
output is still just an ordered list of sprites, just like for the insertion sort.
As for rejecting the 9th sprite I don't do any fancy multiplexer "overload" testing at all. The code just tries to optimistically display as many sprites as possible and if doesn't fit then it's just not displayed (at least that's what happens in the type of multiplexer I wrote). |
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chatGPZ
Registered: Dec 2001
Posts: 11350 |
Quote:
As for rejecting the 9th sprite I don't do any fancy multiplexer "overload" testing at all. The code just tries to optimistically display as many sprites as possible and if doesn't fit then it's just not displayed (at least that's what happens in the type of multiplexer I wrote).
thats probably how most game multiplexers work. (look at SEUCK...argl =D) |
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Oswald
Registered: Apr 2002
Posts: 5086 |
you cant doublebuffer d800 :) for the bucket sort, I have to think it through as I'm totally new to this idea .) ie a multiplexer relies on the sorted list, wont bugs happen when sprites regs are not written in the order they should be ? :) |
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doynax
Account closed
Registered: Oct 2004
Posts: 212 |
Quote: you cant doublebuffer d800 :) for the bucket sort, I have to think it through as I'm totally new to this idea .) ie a multiplexer relies on the sorted list, wont bugs happen when sprites regs are not written in the order they should be ? :)
Really? Feel free to disassemble the code :)
As for the sprites if they aren't perfectly in order then the worst that can happen is that they won't be as tightly packed as possible. If it's properly written anyway. |
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chatGPZ
Registered: Dec 2001
Posts: 11350 |
keep in mind that eg your first "logical" sprite doesnt always have to be the first hardware sprite, it could be any of the 8 hardware sprites in the first bucket. you only have to maintain that if priorities matter (which they often dont in games, since sprites dont overlap) |
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doynax
Account closed
Registered: Oct 2004
Posts: 212 |
Quote: keep in mind that eg your first "logical" sprite doesnt always have to be the first hardware sprite, it could be any of the 8 hardware sprites in the first bucket. you only have to maintain that if priorities matter (which they often dont in games, since sprites dont overlap)
In fact it's often useful to write them in reverse order to insure reasonably good priorities in top-down games and the like (i.e. so lower sprites overlaps the higher ones).
Another possibility is to "center" the multiplexer in such a way as to insure the priority of a single sprite (i.e. always assign the player to the first sprite). |
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Oswald
Registered: Apr 2002
Posts: 5086 |
you might miss sprites otherwise possible to display with the bucket sort.
spr1=70
spr2=74
bucket sort result:
spr2
spr1
then you fire an irq for the next sprite that will be spr2, and already late from spr1 |
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doynax
Account closed
Registered: Oct 2004
Posts: 212 |
Quote: you might miss sprites otherwise possible to display with the bucket sort.
spr1=70
spr2=74
bucket sort result:
spr2
spr1
then you fire an irq for the next sprite that will be spr2, and already late from spr1
The way I do it is to attach the IRQ to the end of the last use of the new sprite, and thus try to reprogram the "channel" as soon as possible. Then all you have to do is check if you're too late to generate next IRQ (if it is to run before the current scanline) and if so jump straight to the next handler. |
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cadaver
Registered: Feb 2002
Posts: 1160 |
If you preprocess the sprite-IRQs, you can take care to always take the upmost Y-coordinate as the basis for the IRQ, even if it isn't the first sprite in sort order. Did this in MW1-3 which had inexact sprite sorting. Brr, never again! :) |
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chatGPZ
Registered: Dec 2001
Posts: 11350 |
now you are assuming too much :) ofcourse the displayer code must be written in a way that such thing can not happen. |
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