[Ohrrpgce] snapping an NPC or hero to grid

[Ralph Versteegen]

I think it's far better to implement this as a command instead of a
script, because we might want to change how it's done in case we add
features like pixel based movement. It seems a bit strange to add an
argument putNPC, because that's for pixel based positioning, maybe it
makes sense to add it to setnpcposition.

Also, the fact that everything breaks horribly when things are
misaligned is definitely an engine bug. Can't we fix it? I'm sick of
treating ancient bugs as features. We can keep the current
code/behaviour around (activated by a backcompat bitset), and try to
fix things so that if an NPC/hero is misaligned collision detection
still works, and it's automatically realigns when moving.

On 9 July 2016 at 05:59, Adam Perry <arperry at gmail.com> wrote:
> It might even be the kind of thing you want at the engine level. The
> original Legend of Zelda allowed semi-freeform movement, but you snapped to
> the half-tile when you switched between moving horizontally and vertically.
> The same thing could work here.

We could follow something like that approach (realign both X and Y
when doing a movement), but snapping to the nearest tile when you move
would probably look quite bad especially if you're not using half
tiles. But there's no need; just realign only in the direction of
current movement.

Aside from that, and thinking about implementing pixel-based movement,
I guess the Legend of Zelda system (with full tiles instead of half
tiles) has several benefits compared to fully free movement. It makes
collisions and obstructions simple: each walkabout occupies/obstructs
either 1 or 2 tiles (in the OHR only one tile at a time is obstructed,
except for NPC activation which checks both tiles). And everything is
basically just as aligned with the tile grid as tile-based movement,
avoiding alignment problems when fitting through gaps. You can pack
more moving NPCs into a given area (although fewer than the current "1
tile obstruction" system). It could be done without snap-aligning,
such as making a diagonal step when switching from horizontal to
vertical movement.


> On Fri, Jul 8, 2016 at 12:56 PM, James Paige <Bob at hamsterrepublic.com>
> wrote:
>>
>> I was talking to RMZ about how to unstick NPCs that get stuck when their
>> speed
>> changes while moving. I know Pepsi has had to do a ton if this sort of
>> thing too.
>>
>> I came up with:
>>
>> script, snap npc, arg, begin
>>   # Kill current movement
>>   walk NPC(arg, west, 0) # x axis
>>   walk NPC(arg, north, 0) # y axis
>>   # reset NPC to current tile
>>   put NPC(arg, NPC x(arg), NPC y(arg))
>> end
>>
>> And I was thinking this is probably common enough that it should be done
>> with standard commands.
>>
>> Maybe a built-in "snap NPC" command? Or maybe an optional argument to "put
>> NPC" that can kill current momentum?
>>
>> Thoughts?
>>
>> ---
>> James
>>
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