Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: jamin1@psu.edu (Jamin Frederick)
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Re: non-displayed sprites
Date: Wed, 06 Aug 1997 08:19:20 GMT
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On Tue, 05 Aug 1997 11:27:17 -0500, Spellweaver
<spelwevr@ix.netcom.com> wrote:

>Quoth Ed Federmeyer:
>   > Mario Perdue wrote:
>   [ ... ]
>   > > Setting them off screen would probably work, however, bit 31
>   > > of the Sprite attribute controls the sprite display mode.
>   > >     0 = displayed
>   > >     1 = not displayed
>   >
>   > I think I don't understand something here.  If you have a bunch
>   > of sprite data structures defined in main RAM, and don't want
>   > some of them displayed, why not just "not sort them" into the OT?
>   > In other words, only call GsSortSprite() on the sprites you want
>   > displayed.  I'm not quite sure what you get from sorting in a
>   > sprite with an attribute bit 31 set to 1 (not displayed).
>
>If you have all of the sprites in a large array, then you can just
>run through the array GsSort[Fast]Sprite()ing all of them, without
>worrying about which to draw and which to skip over.

	I've done a little experimenting with this.  It seems that
frame rate increases when you only insert visible objects (on-screen)
that don't need to be sorted.  This is just done with a positon
comparison with the sprite and the screen boundaries.  Or
alternatively, your sprite list could just consist of those that are
on-screen, so that no comparison is done at sort time, but then you
have to compare the world sprites with the screen sprites to see if
they should now be added to (or deleted from) the on-screen list.  It
seems like the bottleneck is always comparisons of long lists of
sprites.   Sorry if this doesn't make total sense, it's a little late.
:^)


Jamin