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Forums > C64 Coding > Sine sprites in the sideborder. VSP garbage and more

2018-01-22 11:35

Golara
Account closed

Registered: Jan 2018
Posts: 212

Sine sprites in the sideborder. VSP garbage and more

Hello everyone. I'm working on my first C64 demo / intro. I managed to open the sideborder at the top and obviously I immediately put some X-sinus sprites there (I'm still trying to figure out how a DYSP works, right know i have opened lines with 0 and 8 sprites). I noticed that the positioning of the sprites on the X axis is a bit weird. Position 0 is slighty on the left border, but if you want to go all the way to the left you have to use X 500 or there about. My question is, is there some sinus maker or converter that would take care of this ? (so it goes from 0 to ~500 looking like smooth movement to the left). Another question, what is the good way of handling the 9th bit of X position ? What I do is generate a 256 words sinus with values 0 to 500 and use c++ program to split that into 2 256 bytes tables like

sin_1:
1,2,3,4,5,6,7,55,33,....
sin_2:
1,0,0,0,0,1,0,0,1.... where 1 means to set the bit and 0 to not do that.
My sprite 0 is bugging out in the right most border while other sprites display just fine. Why is that ? I've read somewhere that sprite 0 is evil, but could not find any details on why.

I also do VSP by turning on the screen at the right moment together with XSCROLL for smooth scrolling. I see few pixel lines of garbage just above the image, I cover that with the illegal screen mode, disable it at line 56. Is that a good idea ? Another thing about VSP is that it seems to move the whole screen down by one char on the scrolled side (makes sence I guess, as the part of the chars that are outside of the image are displayed on the next text line). So should I copy the 25 lines of graphics in each column when scrolling for seamless scroll or do people not do that ?

Here's a picture of what it looks right know. A big mess !
(PETSCII picture by Archmage as a placeholder. I can't find any pics in binary and that was the easiest to take out of a compiled prg) Hope you have the patience to help a lamer out.
https://i.imgur.com/byWFRsH.jpg[/url]

HughJass from Poland

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2018-02-05 19:56

Rastah Bar

Registered: Oct 2012
Posts: 336

Perhaps you get another irq at line 256+50? I don't see an acknowledgement of the interrupt by writing to $d019.

2018-02-05 20:05

Golara
Account closed

Registered: Jan 2018
Posts: 212

+MACROAckRasterIRQ_A
Acknowledges irq
EDIT. Changing the first logo from Y 52 to 53 fixed the flicker ! Damn man, I'm 110% sure I made bigger gaps between and interrupt and sprite position before and that didn't work. I feel stupid

Now I'm just thinking how to neately scroll in the sprites, since they are double wide, they pop up... And how to do full screen FLD and scroll it back up slowly as the logos fly in without doing interrupts every 7 lines (is that even possible ?)

EDIT. And I made it scroll smoothly from behind left border. This computer is the best, the smallest thing is so satisfying once it works.

2018-02-06 10:26

Mixer

Registered: Apr 2008
Posts: 423

There is a nice monitor feature in Vice. Give command "until <address>", and return from monitor, and it runs the code until PC is in that address and then enters the monitor again. It is setting a break point in a dynamic way.

Then give command r, and you can see the line and cycle where the vic is drawing currently. That is an excellent way to trace raster issues.

2018-02-06 11:08

Dano

Registered: Jul 2004
Posts: 228

First of all, really impressive what you're up to already. Kudos for that!

As for more visually debugging c64 code there is also a REALLY nifty and nice tool i actually use every day now and i could not live without:

C64 Debugger V0.64

takes the pain out of going through vice mon. although for pros it might not be as mighty as vice mon is.

2018-02-06 16:40

Golara
Account closed

Registered: Jan 2018
Posts: 212

Quote: There is a nice monitor feature in Vice. Give command "until <address>", and return from monitor, and it runs the code until PC is in that address and then enters the monitor again. It is setting a break point in a dynamic way.

Then give command r, and you can see the line and cycle where the vic is drawing currently. That is an excellent way to trace raster issues.

I was looking for this r command for a long time, I know vice monitor shows line and cycle when hitting a breakpoint, but doesn't on step. Thanks. With all the tools we have now, instant compilation, nice editors, freezer with no side effects, even showing on which cycle we are, vice with debug border mode.... And it's still pretty hard. I have more and more respect for the guys of the early days more each day I do more coding.

Thanks dano and all others in this thread. I'm surpriced myself that it is going so well, I honestly expected to code some raster bards and 1x1 scroller at best for my first prod, but it all goes rather smoothly for me and in fact I wasn't so invested into something in a long time. This is really fucking cool man.

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