Fast forward in original Lemmings?

[motorollin]

During my time off Uni I've been working my way through Lemmings 2 again. Once I've finished it, I've been thinking of going back to the original Lemmings, but I don't think I could bear to do it now I've got used to fast forward :lol: So I was wondering whether it would be possible for the WHDLoad version of Lemmings to hack a fast forward mode? Maybe it could monitor a keystroke which would toggle the frame rate of the game between normal/double? Can WHDLoad do that?

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moto

[bloodline]

motorollin wrote:
During my time off Uni I've been working my way through Lemmings 2 again. Once I've finished it, I've been thinking of going back to the original Lemmings, but I don't think I could bear to do it now I've got used to fast forward :lol: So I was wondering whether it would be possible for the WHDLoad version of Lemmings to hack a fast forward mode? Maybe it could monitor a keystroke which would toggle the frame rate of the game between normal/double? Can WHDLoad do that?

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moto

L2!!! A great game... :-)

Hmmm, think the processing required for the 100 ok screen lemmings of the original was actually quite extreme... I wrote a lemmings clone back in the day, and it was very CPU/Blitter intensive... So adding a fast forward mode probably would be limited to the Chipset/CPU speed... But if you were serious about this maybe someone could patch out the VBL waiting code... :-/

[motorollin]

bloodline wrote:
L2!!! A great game... :-)

After all these years, I have once again become totally obsessed by it! I have just finished 7 tribes, all with gold medals on every level :afro:

bloodline wrote:
Hmmm, think the processing required for the 100 ok screen lemmings of the original was actually quite extreme... I wrote a lemmings clone back in the day, and it was very CPU/Blitter intensive... So adding a fast forward mode probably would be limited to the Chipset/CPU speed...

L2's fast forward seems to work really well, and there's probably more going on in that than in the original due to all the new skills and traps.

bloodline wrote:
But if you were serious about this maybe someone could patch out the VBL waiting code... :-/

What's VBL waiting code?

Edit -
Ahh, Vertical BLanking. I guess changing that would adjust the amount of time between frames?

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moto

[bloodline]

In L2 there were much less lemmings per level :-)

VBL = Vertical Blanking Line, in your main loop you have a small price of code that waits for interrupt 5, that synchronizes the display with the gfx and gives you silky smooth gfx... At the expense of limiting you to 50fps and ensuring that everything has to be completed in 25ms :-)

[motorollin]

bloodline wrote:
In L2 there were much less lemmings per level :-)

True, but it varied in Lemmings 1. Some levels only had 10 :-)

bloodline wrote:
VBL = Vertical Blanking Line, in your main loop you have a small price of code that waits for interrupt 5, that synchronizes the display with the gfx and gives you silky smooth gfx... At the expense of limiting you to 50fps and ensuring that everything has to be completed in 25ms :-)

So if you remove that from the loop could you manually control the framerate?

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moto

[bloodline]

Most levels in L1 had a lot more lemmigs than L2... It probably averages out to 90...

Well removing the VBL would allow the game to execute as fast as the hardware can run it (with really sh1ty gfx) :-)

[motorollin]

Well an accelerated Amiga might be able to do it. Wouldn't it be better to control the framerate and make it double rather than removing the delay between frames and allowing it to go as fast as the hardware can go? Would such a change be possible with a patch to the WHDLoad slave?

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moto

[bloodline]

I guess you might be able to add a busy loop with a variable loop counter to control the rate... :-)

Anyway, no matter you will still be limited by the blitter :-)

[motorollin]

Tell you what. If you make the necessary changes, I promise to stop being lazy and get on with my album ;-)

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moto

[bloodline]

motorollin wrote:
Tell you what. If you make the necessary changes, I promise to stop being lazy and get on with my album ;-)

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moto

Hahahaha :-)

Without the source code I'd be stumped! It's been 15 years since I looked at 68k asm... Reading some disassembly would be horrific now... :-) I've even forgotten all my chipset reg offsets too :-o $dff180 is all I remember

[motorollin]

$ddf180 sounds like as good a place to start as any! :-P

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moto

[Naton]

Don't forget to play through Lemmings 3D! :-o

[bloodline]

motorollin wrote:
$ddf180 sounds like as good a place to start as any! :-P

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moto

$dff180 if memory serves, is colour register 0... I used to poke random values in there to check if that part of the code was executed or not... simple debugging before we had things like GDB (I love Xcode!!!) :-D

[bloodline]

Naton wrote:
Don't forget to play through Lemmings 3D! :-o

I found L3D tedious... :shrug:

[weirdami]

I remember things moving a little bit faster when I scrolled so that all the lemmings were off screen.