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2x BALL in one line


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#1 Lazycow OFFLINE  

Lazycow

    Space Invader

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Posted Sat Sep 24, 2016 9:22 AM

Hi, I am working on a testkernel which should move 2 BALL sprites next to each other in one line horizontally. (for multiple lines)

 

The testkernel successfully moves 1 BALL horizontally by setting RESBL, HMBL and WSYNC, HMOVE in the next line.

 

I can also setup 2 BALL sprites next to each other, but then they are not moving correctly.

 

Now I need some help, how do I setup this? Is it even possible to move 2 BALL sprites next to each other? I only know "Galaxian", which displays more than 6 player sprites in one row, so I guess it should be possible? But how?



#2 SpiceWare ONLINE  

SpiceWare

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Posted Sat Sep 24, 2016 10:19 AM

The moveable objects (sprites on modern systems) on the Atari are known as PLAYERs, MISSILEs and BALL.  You get 2 each of the PLAYERs and the MISSILEs, but only 1 BALL.  If you want to use the BALL multiple times on a horizontal line you would normally use flicker and draw BALL A on even frames, BALL B on odd frames.

 

The PLAYERs and MISSILEs can be set for duplicate and triplicate mode (via NUSIZ#) which lets you get up to 6 of them per scanline.  You get additional copies via the RESP# trick, which is a bit advanced for newbie.  That link, as well as other useful information, can be found at MiniDig which contains the best of the old stella mailing list.



#3 BNE Jeff OFFLINE  

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    Chopper Commander

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Posted Sat Sep 24, 2016 10:47 AM

Hi, I am working on a testkernel which should move 2 BALL sprites next to each other in one line horizontally. (for multiple lines)

 

The testkernel successfully moves 1 BALL horizontally by setting RESBL, HMBL and WSYNC, HMOVE in the next line.

 

I can also setup 2 BALL sprites next to each other, but then they are not moving correctly.

 

Now I need some help, how do I setup this? Is it even possible to move 2 BALL sprites next to each other? I only know "Galaxian", which displays more than 6 player sprites in one row, so I guess it should be possible? But how?

 

Are you using RESBL to make the ball appear twice on a line?  If so, your HMOVEs will not be very effective.  You can achieve what you are attempting if you use missiles 0 and 1, or a ball and a missile.



#4 Lazycow OFFLINE  

Lazycow

    Space Invader

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Posted Sat Sep 24, 2016 11:14 AM

Yes, I know this post in the Stella mailing list for the RESPx trick, but it didn't help me. I cannot find any hints how to handle the HMOVE correctly with this trick.

Also, it has to be the BALL, because PLAYER and MISSILE have the wrong color.

 

I think 7 PLAYERs in Galaxian are kind of a RESPx trick and these 7 PLAYERs are moving horizontally.

So is it possible to move 2 BALLs next to each other as well? I never read something about a RESBL-trick...


Edited by Lazycow, Sat Sep 24, 2016 11:15 AM.


#5 Lazycow OFFLINE  

Lazycow

    Space Invader

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Posted Sun Sep 25, 2016 11:29 AM

Ok, the sprite trick section in the "2600 advanced prog guide" explains how to postion multiple sprites.

(the guide seems to confuse vertical positioning with horizontal positioning, though)

Anyway, seems like you're right, BNE Jeff. It's not possible to use HMOVE. DOH!



#6 tschak909 OFFLINE  

tschak909

    Stargunner

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Posted Sun Sep 25, 2016 11:49 AM

Because of the way HMOVE is implemented in the logic (you can study the schematic, if you wish), you can't trigger HMOVE multiple times in a line, because HMOVE is in and of itself a sort of delay line, which is highly dependent against the timing of the horizontal blank.

 

-Thom



#7 BNE Jeff OFFLINE  

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Posted Sun Sep 25, 2016 12:25 PM

Maybe post some of your code and a mock up of what you're trying to do.  I'm sure something can be worked out.

 

Do your players appear on the same horizontal plane as the balls?



#8 Lazycow OFFLINE  

Lazycow

    Space Invader

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Posted Sun Sep 25, 2016 3:14 PM

As this is my 1st kernel, I might have to ask something again. Thanks for the support! ;-)

I will try withough HMOVE, that might work as well. Maybe, let's see...






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