okay, so I want more sane physics. it's not been good making plants etc.
police themselves. the engine must enforce some forms of conservations.

first, gravity.
I've thoiught for a long time that accg should be an attribute of the
metaroom, not the object. it just makes sense. but, I didn't think of a way to
do cool things like helium balloons properly. mass doesn't really cover it; I
	had forgotten another thing from reality- density. reality gives such
	lovely examples of how to solve these problems... 
so. mass, density and size are connected. throw in gravity and you also have
weight.
weight is a function of accg and mass, and should never be directly
controlled. I suppose it should be readable, though.
accg is set by the metaroom. that way the moon can have less gravity.
mass is one of those special things in our world that obeys strict laws of
conservation. you can make it from energy, or turn it into energy, but it
can't come from nowhere. so, an object gets a mass when it's created, where it
comes from is TBD (perhaps take some of the parent's mass and/or energy), and
that can't be directly changed. perhaps it can burn off some of that mass for
energy, but it can't just give itself more mass.
density and size are closely linked. if something is less dense than air, it
goes up like helium. if it's more dense, it falls. if it's between the density
of air and water, it's like platic. this gives us one of those wonderful
unexpected bonuses that tells you you're on the right track: if rooms have a
density too (the density of the air, water, etc. filling them) then you can
have an object that floats on water but falls through air :D no fiddling about
with perm vars to try to get an ocean surface.
one problem I haven't decided on, though... if both density and size are
changed, then mass must also change. so, either the user gets control over
just one of density and size... or a change in one will affect the other.
I think the second option is better; if only density was settable and you
wanted a particular size regardless, then you'd have to do evil maths. so.
yes, they can both be changed, but they affect each other.

hmm. but if mass changes, which does it affect? I guess it all depends. I
would say best to default to density- changes in size have a way of causing
trouble. :)

one more thing- I want a strict distinction between regular objects that are
bound by these rules, and special objects that can do what they like (gui
stuff, dev tools, etc).
since we already have two names for objects, let's re-use thatm. agents can be
the special ones (agents in the matrix could do special things too, right?)
and the normal ones can be objects or cobs. cob is a fun word :)

also, to enforce conservation, cobs can't just create objects recklessly. the
rules should be designed to discourage any one plant from taking over the
world... and hopefully outright stop it from creating so many of itself that
the world is lagged to death.
so... in order to create something, it has to come from somewhere. that means
the cob will have to give some of its energy and mass to the child. that way
you'll probably see more realistic growth.. when an animal is pregnant, it
needs to eat more, gain mass, then when it's ready it makes a new cob (either
egg or baby) with that mass.

hrm. but when I talk about size... what do I mean? is the size related to the sprite? does it afect where the object can go? is it just some abstract semi-meaningless variable? I guess it depends on how other things are designed.
another thing about mass is, you could stop creatures picking up really big things. I know it looks funny when a creature is carrying around a vendor bigger than itself... :) but imho it'd be nice to stop that from happening without explicitly setting to to be unpickupable. then maybe only adults would be strong enough to pick up eggs n'stuff.