Playfield Pixel Collision Precision Changes

[KevKelley]

This is a little weird one to try and explain but I will try my best. 

 

Recently I was watching @ZeroPage Homebrew play Litterbug! and afterwards I had gone to test some things or try to replicate their experience and noticed some differences from when I had last tested.  More specifically, one difference I had noticed involves the fire button and the missile sprite coordinates and using pfpixel.

 

Previously I had noticed that it was possible to press the fire button and have the possibility to turn on two pfpixels at once but after I made some fixes I found that was not possible anymore.  I had found the cause of this change.

 

I had made this line:

if joy0fire then pfpixel temp3 temp6 on:p{4}=!p{4}:p{5}=!p{5}:w001=14:score=score+1:w004=r004-1:r=63:var7=var7+1

into this:

if o{0} then pfpixel temp3 temp6 on:p{4}=!p{4}:p{5}=!p{5}:w001=14:score=score+1:w004=r004-1:r=63:var7=var7+1

where o{0} is defined earlier in the code where joy0fire is pressed but before the drawscreen and that line found afterwards.

 

I was wondering why if nothing else is changed but just the o{0} and joy0fire it would result in a change like this?  Does it have something to do with how the Atari may read certain things, like a bit versus a joystick register?

[+Random Terrain]

Are you sure the joy0fire check isn't hidden under some other chunk of code and being ignored sometimes?

[KevKelley]

3 hours ago, Random Terrain said:

Are you sure the joy0fire check isn't hidden under some other chunk of code and being ignored sometimes?

I don't think so. In this loop I had only a couple instances of using it. One defined the bit and one would turn the pixel on. I will have to now double check.

 

I did play around with moving drawscreen around to different places and swapping the bit and joy0fire code to see how it worked and I think it had same effect - it was more precise. That made me wonder if there was an order of operations.

[+Gemintronic]

My gut feeling is that there's a lot of code in that one line.  Everything from bitwise operations to manipulating the score.  You might wanna make that a simple if .. then .. goto statement and put all that in a separate label - one line at a time.  At least it would be easier to eyeball for debugging.

 

I realize that's not an answer in itself but that'd be my first step in unraveling the mystery

[KevKelley]

4 hours ago, Gemintronic said:

My gut feeling is that there's a lot of code in that one line.  Everything from bitwise operations to manipulating the score.  You might wanna make that a simple if .. then .. goto statement and put all that in a separate label - one line at a time.  At least it would be easier to eyeball for debugging.

 

I realize that's not an answer in itself but that'd be my first step in unraveling the mystery

I just moved a bunch of videos to free up space in the first bank so that I can try to clean things up a bit. I may do just that and try. If I play on hardware and no issues arise I may not need to make any changes but I had thought it interesting.