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My attempt at racing the beam, I think.


4 replies to this topic

#1 Pantomchap OFFLINE  

Pantomchap

    Space Invader

  • 16 posts

Posted Sun May 21, 2017 10:33 PM

So I was trying my hand at making an asymmetrical playfield, or at least only one side of the playfield existing. It worked well I would say. It cuts PF2 on scanline 3 right before it has a chance to be displayed on the right half of the screen. CTRLPF is set to #1.

Also, the name of the file has nothing to do with the program's actual inner workings. I was thinking of making a display for a score but I decided it's better to leave something so complicated for later.

Another thing, I had some comments in the .asm file but I decided to remove them because I didn't want to risk giving any incorrect information about the program.

 

 

Any suggestions to make the code better or more efficient?

Attached Files


Edited by Pantomchap, Sun May 21, 2017 10:35 PM.


#2 Gip-Gip OFFLINE  

Gip-Gip

    Chopper Commander

  • 205 posts
  • Location:Georgia, US

Posted Mon May 22, 2017 5:58 AM

So I was trying my hand at making an asymmetrical playfield, or at least only one side of the playfield existing. It worked well I would say. It cuts PF2 on scanline 3 right before it has a chance to be displayed on the right half of the screen. CTRLPF is set to #1.

Also, the name of the file has nothing to do with the program's actual inner workings. I was thinking of making a display for a score but I decided it's better to leave something so complicated for later.

Another thing, I had some comments in the .asm file but I decided to remove them because I didn't want to risk giving any incorrect information about the program.

 

 

Any suggestions to make the code better or more efficient?

I don't have anything at the moment, except you're missing VBLANK at line 55. Once I'm able to test it I will



#3 BNE Jeff OFFLINE  

BNE Jeff

    Moonsweeper

  • 286 posts
  • Location:Virginia, USA

Posted Mon May 22, 2017 7:22 PM

Sure..  Here's a couple of things..

 

Your second load/store is redundant here:

	lda #%00000000
	sta PF2
	sta WSYNC
	lda #0
	sta PF2

Also, hit Alt-L when you are running it in Stella and you can see your scan line count is a bit off.

You can fix that by tinkering with your REPEAT amounts.  But fix that VBLANK thing first.


Edited by BNE Jeff, Mon May 22, 2017 7:28 PM.


#4 Pantomchap OFFLINE  

Pantomchap

    Space Invader

  • Topic Starter
  • 16 posts

Posted Mon May 22, 2017 10:05 PM

Sure..  Here's a couple of things..

 

Your second load/store is redundant here:

	lda #%00000000
	sta PF2
	sta WSYNC
	lda #0
	sta PF2

Also, hit Alt-L when you are running it in Stella and you can see your scan line count is a bit off.

You can fix that by tinkering with your REPEAT amounts.  But fix that VBLANK thing first.

 

I fixed the VBLANK thing and the scanline count thing. I believe it should say "262 @  60.00fps => NTSC" right?

I now see some black from the VBLANK intruding in on the visible picture. Is this a problem with my program or Stella?

Attached Files



#5 SpiceWare OFFLINE  

SpiceWare

    Quadrunner

  • 11,310 posts
  • Medieval Mayhem
  • Location:Planet Houston

Posted Tue May 23, 2017 9:36 AM

I now see some black from the VBLANK intruding in on the visible picture. Is this a problem with my program or Stella?

 

 

The black at the bottom?

panto_scoretest_5-21-2017-7.39PM.png

 

A simple test of other games will show that's normal for both the bottom and top of the image:

Adventure (1980) (Atari).png  Canyon Bomber (1979) (Atari).png

 

You'll see that on a real display too, in fact you'll see black on all four sides.

IMG_8649.jpg

 

Since the picture is under your control you can hide the top/bottom if you want by setting VBLANK earlier in Vertical Blank, and later in OverScan, such as in Air-Sea Battle.

Air-Sea Battle (1977) (Atari).png

 

Just beware that if you leave picture output on during VSYNC that it can obscure the Sync signal, resulting in a rolling picture on some TVs.






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