[Polyworld-develop] touch suggestions?

[Larry Y. <lsy...@be...>]

Hi, all  -  Turns out Matt Whitehead is going to be implementing 
touch, on the way to implementing pick-up/release.  Basically, we 
want the critters to be able to distinguish what it is they would be 
picking up were they to express that behavior.

Rather than implement a pick-up/release-food, pick-up/release-brick, 
etc. suite of behavior neurons, we decided to have a single 
pick-up/release neuron, and the ability to distinguish items by touch 
(as well as vision, of course).

We also decided not to have multiple unique touch neurons 
(touching-food, touching-a-brick, etc.), or unique tags for each item 
(0001 for food, 0010 for bricks, etc.).

Instead, we're going to have a suite of touch sensations that have 
continuous values between 0.0 and 1.0:

   smooth - rough
     soft - hard
     cold - hot   (0.5 is neutral)
      dry - wet
pleasure - pain  (0.5 is neither)

and then assign a value for each of these dimensions/sensations for 
each type of object in the world, as in:

        food  brick  critter  barrier  edge  firepit  underbrush       nothing
rough    .6    .8      .4       .5    0.0      .5    depends on size    0.0
hard     .3   1.0      .3      1.0    1.0     0.0    depends on size    0.0
hot      .5    .5      .6       .5    0.5     1.0        .5             0.5
wet      .3   0.0      .2      0.0    0.0     0.0        .1             0.0
pain     .5    .5      .3       .5    0.5     1.0    depends on size    0.5

and so on.  (Those are just off the cuff numbers.  Nothing set in stone.)

The point of telling everyone this is to solicit suggestions for 
other sensations that might be appropriate.  Anything come to mind?

- larryy

P.S. For example, I just thought of curved - pointy, though I don't 
know if it's particularly useful.