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Demos Amiga Demoscene Archive Forum / Coding / Blitting with offsets.

 

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korruptor
Member
#1 - Posted: 22 Jan 2007 18:09
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Hi again :D

Sorry for another, likely, stupid question but I can't see the wood for the trees again...

I'm pretty far along with making my own sine scroller, but I've got this odd problem when adding offsets to the height. If I do 2 pixel column blits, the first 2 blits are wrong and if I do single pixel column blits the first four pixels are wrong.

I've stopped using my sine table and atm I'm purely adding 40 to the blitter's destination pointer, so that each blit is on the next line. Here's what I've got with 2pix wide blits right now:

See the screen shot:

Dodgy Blits

I can't figure out why anything would be different as I'm using the same loop for all blits. Can anyone slap some sense into me? :D

My source in full is here:

http://kor.gazaxian.com/SineScroller.asm
korruptor
Member
#2 - Posted: 22 Jan 2007 18:14
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Typical. The minute I posted, I found the bug. A zero was missing from the end of the mask. Doh (*slaps forehead*)

Thanks for reading :D
z5_
Member
#3 - Posted: 22 Jan 2007 21:01
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Hmm... it seems that your first sine scroller is getting closer and closer. Good work, Korruptor. cool :o)

I remember when my simple horizontal scroller appeared on screen like it was supposed to be (mind you, i was doing it with sources / tips / ... gathered from different places). It was like magic :o) Soon after, i gave up... :o(
korruptor
Member
#4 - Posted: 25 Jan 2007 21:28
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Yup, got it all working in the end but it's taken lots of reading and looking at code. I do finally have a rough grasp of the blitter though. :D

Just deciding what to do next. Candy bar looks pretty easy. Or a plasma or something...

What happened to your code z5? I've read all your tutorial threads and got some good tips from them. If you've stopped, that's a shame as this boards been an immense help to me.
Toffeeman
Member
#5 - Posted: 26 Jan 2007 01:03
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Korruptor if you want to combine a few effects for a small intro or something let me know. I'm only really into doing the old school effects which seems to be what you are coding :0)
z5_
Member
#6 - Posted: 26 Jan 2007 12:07
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@korruptor:

Add a bit of copper magic (two horizontal bars and a color gradient across the screen to get that smooth colored sine scroller) and a sprite (starfield), you would actually have a real cracktro :o)
z5_
Member
#7 - Posted: 26 Jan 2007 12:45
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What happened to your code z5? I've read all your tutorial threads and got some good tips from them. If you've stopped, that's a shame as this boards been an immense help to me.

As much as i loved learning to code, being in front of a computer for 8/9 hours at work and then coming home for some more was a bit too much. On top of that, i never felt i would be any good at it anyway and my Amiga is falling apart (diskdrive doesn't work, mouse,...). Put all these things together and you know the reason.

However, if ever i find a non computer job and can setup winuae for a bit of assembler, i might retry again for some very modest experimentation. I actually loved seeing the result of my code on screen, though it wasn't much.

I do hope that you will keep it up though, Korruptor.
korruptor
Member
#8 - Posted: 26 Jan 2007 17:27
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Yeah, I'm going to keep at it for a while. I've got E-Uae working on my Mac, which is fine to code on, but it doesn't run anything in a frame so I'm going to have to install XP on this laptop and dual boot if I want to do anything serious.

Really enjoying it though :D

 

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A.D.A. Amiga Demoscene Archive, Version 3.0