Studying Willy's Jumping Animation in Detail

[IRF]

Question: Is there a way of seriously slowing down the JSW game engine, so that one can study the exact pixel placement of Willy at each stage during a jump? i.e. so the screen image is effectively still for a few seconds during every frame of animation?

 

I was thinking some sort of command could be placed in the Main Loop which delays things?

 

Placing him in a field of Water cells whose pixels consist of a grid of horizontal and vertical lines will also help with this task.

Edited April 20, 2016 by IRF

[Spider]

Emulators will usually run at about 60% without issue, any slower and you get odd effects.

 

The one sensible place I guess would be 35343 (remove the jump there) and then you have a few bytes available.

 

Let me take a look at this later if you are not able to come up with anything.

[IRF]

Do you know a command that would have the effect of causing such a delay?

 

EDIT: As it happens, over in a PM I've just been discussing the 'DJNZ' command.  It works on the 'B' register.  I'm now wondering if that was inserted after the register 'B' had been set to a high value (such as #FF), with the operand of the DJNZ set to itself, then maybe it could cause quite a delay?

 

e.g. at 35343, insert 'LD B, #FF.

Then at 35345, 'DJNZ 35345'.

 

The command at 35345 would then take the value of B (which would be initialised to #FF each time the program passes through the main loop) and decrement it by one, then jump back to itself and keep decrementing B until it reached a value of zero, before proceeding with the rest of the program?

Edited April 20, 2016 by IRF

[Spider]

I tried a few methods, mainly a call at 35343 to 65000 so I could safely have enough space to put some code but I could not get it to work properly even when preserving the registers:

 

org 65000
MAIN:
ld c, 3
looper2:
ld b, 127
looper:
push bc
ld hl, 0
ld de, 1
ld (hl), b
ld bc, 767
ldir
ld a, 5
loopy halt
djnz loopy
pop bc
djnz looper
dec c
jr nz, looper2
ret

 

hmm :unsure:

[Spider]

OK sorted this, not quite as I wanted but...

 

35680 LD BC,3 Init duration delay counter

 

Change BC value to 255

 

As that screws the sound up a bit ( ! ) you need to disable it:

 

35683, 35684, both 0 to remove the OUT (254) , A instruction.

 

Summary:

 

POKE 35681,255 or #8B61,#FF

POKE 35683,0 or #8B63,#00

POKE 35684,0 or #8B64,#00

 

Adjust 35681 / #8B61 to adjust the um, 'speed'

 

Toggling in game music on / off will turn this effect on or off. It only slows down when the in game music is "playing" (although you cannot hear it)

 

Jumping sound not effected. :)

[IRF]

Thanks Andy, I'll have a play later.

 

I wonder if I increase the value of 35682 (#8B62) from zero, to anything up to #FF, can I increase the delay further by a factor of up to 256(!)?

Edited April 20, 2016 by IRF

[Spider]

It might not tested. :)

 

255 / #FF is very slow though I think ? :unsure:

[IRF]

*Bump*!!!

[Spider]

Is #FF not slow enough ? :)

 

One way would be to do a jump out of the main loop to higher memory to a 'delay' routine, the jump back again. This could be a bit messy though. :unsure:

[IRF]

I think #FF is slow enough!