Bobbing code for flying Creatures

[9Panzer]

I've been a bit hesitant to share my code since it doesn't always work the same way in other people's projects as it does in mine. As a result, I often get flooded with messages from people insisting it's broken and demanding tech support—like I somehow owe them for publishing it. But recently, while helping RetroBro with his project, he convinced me that this one was worth sharing.

So, enough complaining—let's get to the good stuff! This is a simple yet effective script that adds a touch of realism to your flying objects. It gives them a natural bobbing motion, making them feel more alive and dynamic. Just plug it in, and watch your objects hover with style!

Examples:

Frontiers:

TheRetroBros

The Adventures of Panzer 3

1. First things first. You are going to need 3 Variables.
Bobbing1
Bobbing2
myTinyTimer

2. Next, open your HandleGameTimer and add:

INC myTinyTimer
LDA myTinyTimer
CMP #03
BEQ +reset
JMP +DoneSequence
+reset
LDA #00
STA myTinyTimer
+DoneSequence

3. Open your Handle Physics and add this:

1. LDA Object_type,x ;;;
   CMP #23; Helicopter ;; ADD THE OBJECT NUMBER THAT YOU WANT TO BOB HERE
   BEQ +bobbing
   JMP +NotHelicopter
   +bobbing
   
   LDA vBlankTimer
   AND #%00000001
   BNE +runCode
   Jmp +EndBobbing
   +runCode
   
   LDA myTinyTimer
   CMP #01
   BEQ +runCode
   Jmp +EndBobbing
   +runCode
   
   
   LDA Bobbing1 ; Initialize a counter for bobbing movement
   ; Compare with a threshold value (e.g., 10 or any suitable value)
   CMP #8
   ; If the counter is below the threshold, increment it and continue bobbing
   BCC +IncrementCounter
   ; If the counter reaches the threshold, reset it and change the bobbing direction
   LDA #00
   STA Bobbing1
   LDA Bobbing2
   EOR #01 ; Toggle bobbing direction (e.g., from up to down or vice versa)
   STA Bobbing2
   
   +IncrementCounter ; Label +
   
   ; Increment the bobbing counter
   LDA Bobbing1
   CLC
   ADC #01
   STA Bobbing1
   
   ; Check the bobbing direction (0 for up, 1 for down)
   LDA Bobbing2
   CMP #00
   ; If bobbing up, decrement Object_y_hi,x by 1
   BEQ +BobUp
   ; If bobbing down, increment Object_y_hi,x by 1
   JMP +BobDown
   
   +BobUp ; Label +
   
   LDA Object_y_hi,x
   SEC
   SBC #01
   STA Object_y_hi,x
   JMP +EndBobbing
   
   +BobDown ; Label +
   
   LDA Object_y_hi,x
   CLC
   CLC
   ADC #01
   STA Object_y_hi,x
   
   +EndBobbing ; Label +
   
   +NotHelicopter

After you pop this in you should now have a bobbing object!

One important thing to keep in mind with this code is that it forces the object to move up and down. While it works well for AI-driven horizontal movement, the object will still be pushed into solid surfaces above or below, potentially causing it to get stuck. Keep this in mind when designing your levels!

Good luck!

 

[TheRetroBro]

Great stuff bro! And thanks again for the help. These small details pay huge dividends in the quality!

 

[dale_coop]

Nice tutorial, thanks for sharing it with the community.
And yes, I understand what you mean by:

I often get flooded with messages from people insisting it's broken and demanding tech support—like I somehow owe them for publishing it

Everyone who shares code, writes guides, or creates tutorials faces this "tech support" burden for days after releasing their work. It’s really time-consuming and can sometimes affect motivation or even health.
But beyond those few people, your work will surely help dozens of others who will have no trouble following your guide and for whom your script will be very valuable.

 

[9Panzer]

Nice tutorial, thanks for sharing it with the community.
And yes, I understand what you mean by:

Everyone who shares code, writes guides, or creates tutorials faces this "tech support" burden for days after releasing their work. It’s really time-consuming and can sometimes affect motivation or even health.
But beyond those few people, your work will surely help dozens of others who will have no trouble following your guide and for whom your script will be very valuable.

Thanks for that @dale_coop and I do agree. If it wasn't for people writting this kind of stuff down I would never have been able to learn the system at the level I do. Being able to rip the codes apart and learn from them has always been a big deal for me.