Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!uunet!shelby!rutgers!cbmvax!spence
From: spence@cbmvax.commodore.com (Spencer Shanson)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: How to use BPLCON2?
Message-ID: <19026@cbmvax.commodore.com>
Date: 15 Feb 91 20:06:20 GMT
References: <12181@helios.TAMU.EDU> <18999@cbmvax.commodore.com>
Reply-To: spence@cbmvax.commodore.com (Spencer Shanson)
Organization: Commodore, West Chester, PA
Lines: 33

In article <18999@cbmvax.commodore.com> jesup@cbmvax.commodore.com (Randell Jesup) writes:
>In article <12181@helios.TAMU.EDU> aaron@stat.tamu.edu (Aaron Hightower) writes:
>>Today, I was working on one of my programs that uses both sprites and menus
>>on the same screen.  The problem that I ran into was when I tried to use the
>>menus.  When the menu is pulled down, the sprite(s) overlap the menu.  I
>>read in the RKM Hardware manual and found the chapter on how to set the
>>playfield-sprite priorities, and it mentions that you can use BPLCON2 to
>>set the priorities.  For a 1-Playfield screen, you are supposed to use
>>bits 3,4, and 5.  I tried what the manual suggested, but nothing appeared
>>to change.  The sprites still overlapped my menus.  So how can I do this? 
>>Can I set some flags in the NewScreen structure or something?  Am I writing
>>to the wrong place (I am using 0x104 for BPLCON2?)
>
>	Graphics is probably resetting BPLCON2 every vertical blank.  Remember
>that the hardware tells you what the hardware does, not how that interacts
>with the system software.  You may be able to do it using a user copper
>list to set the mode.
>
>-- 
>Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
You beat me to it, Randell. Yes, graphics.library does change (reset) the BPLCON2
register every VBlank. As Randell says, you will need to install your own
user copper list in your viewport to get your effect.



-- 
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Spencer Shanson - Amiga Software Engineer     | email: spence@commodore.COM
                                              | or uunet!cbmvax!spence
All opinions expressed are my own, and do not | "You know my methods. Apply
(necessarily) represent those of Commodore.   | them" -- Sir Arthur Conan
                                              | Doyle - 'The Sign of Four'