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Message: 4460
Author: andrewbroad
Date: 18/09/2004
Subject: Re: Ladders, Lifts, disappearing platforms, Radzone & Booty
Alexandra wrote:
>I'm sure it's /possible/ to have ladders in JSW, but if there are
> Ok, I'm guessing this is going to be a real pain in the neck, but
> is it technically plausible to create a climbable block type in
> JSW64?
>
> However, the fact that 2 more keys would need to be detected in
> the movement routine, a whole new branch of the movement routine
> would need to be coded (with 2 sprites for 'willy' climbing
> up/down), not to mention the code for the actual block, I'm
> guessing it's either impossible or just too much of a headache.
only a few free bytes left in JSW64, something else would have to
give (e.g. space for graphics).
I don't like it when a game has two separate keys for jumping and
climbing ladders, as in Ghosts 'n' Goblins. It's much more user-
friendly to have one combined up/jump key, as in Ghouls 'n' Ghosts.
Therefore, JSW would just need to add a down-key.
My favourite platform-games other than MM/JSW all have ladders, e.g.
Bruce Lee, Booty, and the Amstrad CPC game Radzone.
Radzone has a block-type which is like floor, ramp and ladder rolled
into one: in a field of these blocks, you can move in eight
directions. Sometimes, these blocks behave as vertical conveyors,
carrying you up or down.
Climbing up ladders isn't a problem in JSW, since you can easily
jump up them as in "Ballroom East". If floor-blocks (or a new ladder
block-type) were defined as down-conveyors, that could eliminate the
need for a down-key.
Another cool feature of Radzone is its radiation-absorbed dose
counter, which behaves like the Manic Miner air-gauge in reverse,
and increases at a rate proportional to the number of items left on
the screen. You can reset the RAD gauge by visiting a safe zone (a
room with no remaining items).
Booty is an interesting platform-game, adding not only ladders, but
horizontal and vertical lifts, platforms that disappear and
reappear, wide doors that take you from screen to screen (a bit like
portals in Manic Miner, but usually two-way), and narrow doors that
you have to unlock with a correspondingly-numbered key.
Some of the items in Booty (the treasures, not the keys) are booby-
trapped - you have to get out of the way fast, before they explode!
Once you have unlocked all the narrow doors on a row, deadly rats
and parrots can cross that row at random times - a bit like arrows
in JSW, but slower.
However, Booty has no jumping, and the screen-layouts are very
limited (floor-blocks can only appear in four rows on the screen)
compared with the arbitrary block-placements of MM and JSW. But it's
a very fun and scary game to play! :-)
It would be nice to have lifts in my next JSW game, Afrikaan. One
possibility might be to make it so that a guardian is a lift iff it
has white ink. Another possibility might be to use Bit 2 of Offset 0
of the guardian-class (40960 + 8*n) to denote lifts, i.e.
Guardian-Type 5 = horizontal lift,
Guardian-Type 6 = vertical lift.
I believe Geoff Mode uses these guardian-types for wraparound
guardians. This approach is more flexible than recognising white-ink
guardians as lifts, but would upset JSW editors (including my own
JSW CK) that only recognise Guardian-Types 1-4 and 0 (unused).
These lift-guardians would be drawn /before/ the player, so that
they would behave like floor rather than kill you.
Horizontal lifts should be relatively straightforward to implement,
but vertical lifts are complicated as they should carry the player
smoothly up and down, without falling or having to jump. I might
have to disassemble JSW II to see how vertical lifts work there - or
perhaps just study the JSW code for ramps and ropes, which carry you
up and down smoothly.
Platforms that disappear and reappear could be implemented using a
patch-vector which sets the colour-attribute of the appropriate
block-type to be the same as the background colour-attribute, and
back again, at regular time-intervals. (This effect can also be
simulated using invalid arrows, but without any fine control.)
--
Dr. Andrew Broad
http://www.geocities.com/andrewbroad/
http://www.geocities.com/andrewbroad/spectrum/
http://www.geocities.com/andrewbroad/spectrum/willy/
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