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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
D011 scrolling
Hi,
What is the best rasterline to flip the D011, when
scrolling the screen ?
No FLD!
Plain old scrolling ?
I have timing error, so the text jumps a bit.
Scroll the colorram too in same scan, takes a lot
of time..
Thanks for ANY help!!
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Oswald
Registered: Apr 2002
Posts: 5094 |
amidog: you're almost right, except that if you have scrolled the screen by 40 columns, it also moves one char row UP. So when starting the process again, you will have to change to another screen, built up while scrolling, to hide the jump one row down, when starting over.
for example at soiled legacy there's a loader part wich swings in a bitmap gfx in from the left, and then it goes out to right, I had to copy the gfx to another bitmap shifted by one char row, and change the display to it, when it started to move its next 40 char. |
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White Flame
Registered: Sep 2002
Posts: 136 |
...plus a full copy of colorram if you're using it, which is the real killer. |
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raven
Account closed
Registered: Jan 2002
Posts: 137 |
@White Flame:
Check out the end-part of Insomnia.
There's a continuous fullscreen bitmap scroll using
DMA delay, including color-ram.
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White Flame
Registered: Sep 2002
Posts: 136 |
Yeah, works great when you can pause the screen for a couple of seconds every 40 chars... ;) |
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AmiDog
Registered: Mar 2003
Posts: 97 |
Well, the only real problem as I see it is the color-ram copy. After all, by using simple double buffering, when you copy a column to the visible screen (it being text, bitmap or whatever), just copy the same column to your second buffer. This will double the amount of bytes to copy for each char scrolled (from 25 to 50 for text), but after you've scrolled 40 chars, you have already prepared the next screen and can easily just switch to it without any overhead what so ever (except for color-ram).
As I found this VSP discussion rather interesting, I've now written my very first VSP routine using the method above (only for text yet though and without using color-ram, but the theory is the same) and it's working nicely. |
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Stingray
Account closed
Registered: Feb 2003
Posts: 117 |
AmiDog, any chance of posting your code here, or is it to long to post? |
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AmiDog
Registered: Mar 2003
Posts: 97 |
The source is a bit long... 16kb actually. But you can get it here:
http://user.tninet.se/~cqj150m/vsp.s
But remember a few things. The sources should be assembled with tass, has very few comments, has only been tested on PAL VICE, has not been optimized at all and doesn't handle smooth scrolling (well, there's some code in there you can enable, but it doesn't set things up properly so you never see the first column etc.).
Also, I'm not very good at 6502 asm so some things are probably done in a far from optimal way. And I've borrowed the stable raster routine from... The Fridge I think it was... |
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Dane
Registered: May 2002
Posts: 423 |
VSP is fun indeed - did my first ever in Game Over, where the last picture of the exlosion is 48x24 chars in FLI. And yes, I'd say that is solved in a rather spiffy way. Bankswitching halfway through the vsp.
Only prob is d800 has to be copied, but then again we're only talking about 24 bytes or so.
I'm sure others have done even neater tricks, but this was just my way of not having to copy lots of graphics to both bitmap, screens and colram. |
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bOOZElEE
Registered: Dec 2002
Posts: 35 |
@amidog
hope you wont mind about my mail...
next time i read everything twice or even thrice to make sure who wants da stuff ;) |
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AmiDog
Registered: Mar 2003
Posts: 97 |
@bOOZElEE
Well, I just noticed that the email address I've got registered here is long gone, so I didn't get any email anyway... |
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