Path: chuka.playstation.co.uk!news
From: Developer Support <dev_support@interactive.sony.com>
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Re: changing resolutions
Date: Fri, 01 Aug 1997 17:12:27 +0100
Organization: PlayStation Net Yaroze (SCEE)
Lines: 50
Message-ID: <33E20AEB.718C@interactive.sony.com>
References: <33E1FCFE.5F42@erols.com> <33E20029.6B6E@erols.com>
NNTP-Posting-Host: 194.203.13.10
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mailer: Mozilla 3.01 (Win95; I)

Clint Kelly wrote:
> 
> Well, I just figured out that I have to use "interlaced mode" to have
> vertical resolutions of 480.  Has anybody out there used interlaced mode
> in any of their programs?  Is it hard?  How much would I have to modify
> my program to use it?
> 
> clint
> 
>


There are not many modifications for hi-res interlace mode;
if your program frame rate is high, you can use it,
and it's often worth if because it does look very nice.

Firstly: GsDefDispBuff(0,0,0,0) for interlace.

Secondly: no need to call DrawSync(0) every frame,
or GsSwapDispBuff() for that matter. 
In interlace, there's one buffer, the odd and even lines
are accesses alternately, providing a quasi-double buffering.

Thirdly: check frame rate (do this: each frame,
use 
hsync = VSync(1); FntPrint("hsync: %d\n", hsync);
this will tell you how many scan lines the program takes
per frame. If it's over 280 it's going to miss frames
(drop below maximum frame rate, 60fps NTSC, 50fps PAL).
--- The reason for all this is that interlace
mode doesn't work properly at less than top frame rate:
you start to get all kinds of flickering etc. 
-- You can stop this flicker and keep it all smooth, at the cost
of some things not getting drawn, by adding the line
ResetGraph(1);		
	// stop drawing, cancel all unfinished draw processes
just after VSync(0).

Fourthly: when calling GsInitGraph, one of the arguments
is GsINTER/GsNONINTER | GsOFSGPU/GsOFSGTE.
Use the value (GsINTER|GsOFSGPU) for interlace.


	-- As far as I can remember, those are the only
changes needed for interlace. I think some of the SCEI
and SCEE sample programs use interlace.

If it doesn't work as suggested above, I'll post some code.

Lewis