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Hack idea for Threshold (Tigervision)


5 replies to this topic

#1 chewy OFFLINE  

chewy

    Chopper Commander

  • 176 posts

Posted Sun Apr 7, 2019 1:13 AM

good shooter, but the scrollling sidegrapics are making me dizzy and seasick (seroiusly!- been getting a little eye fatigue from some of these games lately lol)- anyways- my hack idea is to have get cut those side walls out of the code............



#2 Nukey Shay OFFLINE  

Nukey Shay

    Sheik Yerbouti

  • 21,966 posts
  • Location:The land of Gorch

Posted Sun Apr 7, 2019 4:59 AM

You are using the portable version, right?

 

Sounds like an easy change.  First guess is to remove the playfield pixels altogether...by altering $F6AC to read LDA #$00 instead of #$C0...

tg1.jpg

 

Unfortunately, that PF1 is hiding the inactive bad guys from view.  So instead of that, alter $F6A8 to read LDA #$00 (A9 00) instead of LDA ram_B3 (A5 B3)...the PF color is changed to black.

 

The game recolors playfield on later scanlines, tho.  So you need to change $F78C from ORA #$04 (09 04) to be LDA #$00 (A9 00) as well...

tg2.jpg

 

But there's another problem.  The enemies use the ball sprite to fire on the player.  With PF set to black, the ball is no longer visible.

 

So you either have to put up with the inactive enemies being visible, or make a more-extensive hack which changes the sprite used for enemy missiles.


Edited by Nukey Shay, Sun Apr 7, 2019 5:22 AM.


#3 Nukey Shay OFFLINE  

Nukey Shay

    Sheik Yerbouti

  • 21,966 posts
  • Location:The land of Gorch

Posted Sun Apr 7, 2019 5:34 AM

Or, just match the color of the upper wall for the side walls.

 

Original PAL and NTSC portable versions

Attached Files



#4 chewy OFFLINE  

chewy

    Chopper Commander

  • Topic Starter
  • 176 posts

Posted Mon Apr 22, 2019 1:20 AM

You are using the portable version, right?

 

Sounds like an easy change.  First guess is to remove the playfield pixels altogether...by altering $F6AC to read LDA #$00 instead of #$C0...

attachicon.giftg1.jpg

 

Unfortunately, that PF1 is hiding the inactive bad guys from view.  So instead of that, alter $F6A8 to read LDA #$00 (A9 00) instead of LDA ram_B3 (A5 B3)...the PF color is changed to black.

 

The game recolors playfield on later scanlines, tho.  So you need to change $F78C from ORA #$04 (09 04) to be LDA #$00 (A9 00) as well...

attachicon.giftg2.jpg

 

But there's another problem.  The enemies use the ball sprite to fire on the player.  With PF set to black, the ball is no longer visible.

 

So you either have to put up with the inactive enemies being visible, or make a more-extensive hack which changes the sprite used for enemy missiles.

 

 

HEY MY GUY- THANKS SO MUCH FOR "FIXING" IT- i forgot i posted this but then i got frustered with threshold again and i remember and i was pleasntly suprised to see all your info, and the steps you took.  I am playing on a sunnyvale light 6'er via harmony cart



#5 chewy OFFLINE  

chewy

    Chopper Commander

  • Topic Starter
  • 176 posts

Posted Mon Apr 22, 2019 1:23 AM

soooooo much better.  maybe im overly sensitive to this stuff but i was getting motion sick playing this one- you made the suffering stop



#6 roadrunner OFFLINE  

roadrunner

    Quadrunner

  • 12,267 posts

Posted Mon Apr 29, 2019 2:52 PM

Cool hack. Thanks






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