PDA

View Full Version : Objects and effect targeting - Warning: Lethal to catgirls



jseah
2009-12-04, 10:22 AM
I have a philosophical question to ask. It does have a game impact however.

What is an object?

It's rather important that I answer this question as I'm busy homebrewing a magic system and the definition of an object needs working on.
The exact problem involves defining what 1 object is for a telekinesis-like power.

There's two ideas, but for both of them, I can cook up a weird scenario where they give strange results.
1. A continuous solid body.
Continuous being defined as, "if I pick it up on one point, if the other point follows it, they're continuous between those two points".

Problem: bendy things don't qualify (depending on how rigorous your definition is). And separating glued objects becomes impossible (since you can't target the two halves separately)

2. Caster-defined volume
Caster defines a set volume and says "this is one object"

Problem: Unsure how to distribute force over the volume, could waste a lot of power on 'wind'
Also causes apples to fly out of a cart when you push the whole thing

**************

General problems:
Composite materials are tricky to handle. Liquids and gases are worse.
IE. does each grain of sand on the beach count as separate objects?
Let's say we cast disintegrate (D&D 3.5) on the beach. One grain of sand, or a big hole?
Take the one grain of sand, and place it on a clean table. Disintegrate that, and if you hit it, I have no doubt that many people will agree the table doesn't disappear as well.
Double standard? I dislike those.

So I ask, what would be a satisfactory simplification to the "object" problem?

EDIT:
A friend gave me this suggestion and I made some revisions, this is my current favourite:

Have any continuous object count as 1 object.
- Any body that is made of the same material in contact counts as continuous (eg. water in a lake is continuous, sand on a beach is continuous)
- If two points on the body that will follow when the other is moved, the body is continuous between those two points (rigid bodies are continuous, glued bodies are continuous, cloth is continuous, so is jelly)

For TK, any object that weighs over 1 kilogram or is larger than 1m^3 is divided into sub-objects.
These sub-objects are targeted as one object each and must be less than 1 kilogram.
The shape is caster-defined but must be contiguous, convex and fit in a cube (1m side). The block is allowed to extend out of an object but will not take anything outside as part of the sub-object.
Use the method of division that gives the least number of sub-objects. All variations in that method are allowed, caster chooses one.

Other spells would divide them differently.
The recommendation here is to approximate it by being reasonable, but you can look at the fine rules if the need arises.

The point here being that sand on a beach counts as one object. While allowing you to affect a small portion if need be.
Also prevents you from throwing an entire mountain as parts of it will be out of range. (cube of 1m side)
Prevents you from counting the pebble on the table as part of the table (not of same material and won't follow)
It also allows you to count pebbles in a bag as one.

Still, it does make a mixture of black and white sand count as a million different objects. Which is irritating.

Johel
2009-12-04, 10:38 AM
An object is any single mass that isn't part of a creature and that can reasonably be lift or moved, provided one has enough strength to do it.

As such, a mountain isn't an object but the rocks on its slopes are.
A chain, while composed of several small metal pieces, is a single object, since those object form a single mass.

Ten rubber balls glued together count as a single object as long as they remain stuck together. This, however, means you won't be able to move any of these balls, should the total weight exceed the lifting capacity.

A creature is anything that can move on its own will, even if it's with limited initiative. As such, constructs and mindless undeads are creatures but chairs aren't, unless you animate them.

Telekinesis by RAW has a limit on number of objects and total weight of objects. The "number" part prevents you from hurling hundreds of light objects at something. The "total weight" part prevents you from simply lifting a cart full of iron. No "volume" is accounted for but there's the famous "10 ft between each object you hurl at the target".

Cyrion
2009-12-04, 10:40 AM
This may seem like something of a cop out, but I'd go for a "user-defined" object ruling. The reasoning behind it though- magic/sorcery/psionics are traditionally considered to be governed by the user's will. By sheer dint of force of personality I tell the rules of the universe to shut up and go sit in a corner whilst I toy with reality. As such, what gets considered one object should be, to a certain, extent defined by the controller of the magic. Most people would be able to hold in their minds the concept of an apple cart with its apples as one object or to separate the ideas and move just the apples.

Gamewise, this allows you to moderate the situations intelligently as a DM. If what the mage is doing seems reasonable, don't give him any grief. If it's abusive, you don't have to argue the physics behind it. If it's borderline, you can set an appropriate DC Will (or maybe even CHA) check and say that if he can make it his mind was sufficiently flexible enough to effect that idea of an object.

ocdscale
2009-12-04, 10:42 AM
There's two ideas, but for both of them, I can cook up a weird scenario where they give strange results.
1. A continuous solid body.
Continuous being defined as, "if I pick it up on one point, if the other point follows it, they're continuous between those two points".

Problem: bendy things don't qualify (depending on how rigorous your definition is). And separating glued objects becomes impossible (since you can't target the two halves separately)


Why wouldn't bendy things qualify? One 'half' of the bendy thing might not follow the half you pick up immediately, but it will follow eventually. Although the "pick up->follow" definition is definitely ripe for abuse.
"Continuous solid body" seems like a fine definition to me. If it means they can only disintegrate one piece of sand at a time, them's the breaks.

As for separating glued objects, I don't see that as a problem. It's not as if it would be impossible to do in the game, only impossible to do via the homebrew TK.

Some possible alternatives:
Instead of defining TK as working on objects, define it as creating a force. Permit the player to project a force of N newtons over A sq. ft. So he can push, lift and squash. Require line of sight (no "pushing" something's heart into their ribs) and permit projecting negative force (so they can "pull"). Allow greater skill to create more than one plane of force simultaneously so they can crush/separate. Probably simplify it such that the creation of 3 or more planes of force can simulate a hand.

Alternatively, just define TK as manifesting a hand of force, of variable size, force 'density', and dexterity. Gross manipulation (push/pull/punch) requires one level of skill, fine manipulation (twist/open/carry) requires another, ultra-fine manipulation requires yet another. Require higher level of skill to manifest smaller hands.

Random832
2009-12-04, 12:31 PM
Require line of sight

Line of effect. Fog shouldn't block TK.

jseah
2009-12-04, 01:37 PM
Thanks for the suggestions:

Johel: This is a homebrew system, unrelated to D&D, I just used the disintegrate thing to illustrate the problems with user-defined and continuous body.
I appreciate your point that we should use the solid object definition though. How would you apply that to the disintegrate-the-beach problem?

Also, that definition leads to counting the entire lake as 1 object.

Cyrion: User-defined is nice. But force over volume gets to be a problem in the lethal-flying-apples way. Due to the force needed to move the cart being much higher than the force needed to move the apples.
There's also the general Simulationist sense I'm going for, that tends to turn weak abuse into interesting phenomena. So strange effects like taking the outside of the object as separate from the inside and peeling it like an orange might be useful.

It does seem to solve a lot of problems however, as I can tie effect to skill.

ocdscale: Bendy things not qualifying is if you insist on a rigid body. The insistence is due to a problem with targeting water in a lake. Coz if non-rigid bodies count, then water could conceivably count as one. (if water doesn't, how about jelly? or concrete foam? XD)

Force over area is one thing I considered before and was going to add to this later.
The problem with the force over volume is this:
If I apply constant pressure over the volume of a cart with apples, the apples move faster since they're less dense than the cart. Which results in the apples splattering all over the unfortunate foolish farmer who enlisted the help of a mage.

The hand of force thing is nice, but I'm dealing with a basic effect here. I certainly intend hands of force to be possible, but they aren't going to be the only form of TK.

-------------------------------------------------------------------------

A friend gave me this suggestion and I made some revisions, this is my current favourite:

Have any continuous object count as 1 object.
- Any body that is made of the same material in contact counts as continuous (eg. water in a lake is continuous, sand on a beach is continuous)
- If two points on the body that will follow when the other is moved, the body is continuous between those two points (rigid bodies are continuous, glued bodies are continuous, cloth is continuous, so is jelly)

For TK, any object that weighs over 1 kilogram or is larger than 1m^3 is divided into sub-objects.
These sub-objects are targeted as one object each and must be less than 1 kilogram.
The shape is caster-defined but must be contiguous, convex and fit in a cube (1m side). The block is allowed to extend out of an object but will not take anything outside as part of the sub-object.
Use the method of division that gives the least number of sub-objects. All variations in that method are allowed, caster chooses one.

Other spells would divide them differently.
The recommendation here is to approximate it by being reasonable, but you can look at the fine rules if the need arises.

The point here being that sand on a beach counts as one object. While allowing you to affect a small portion if need be.
Also prevents you from throwing an entire mountain as parts of it will be out of range. (cube of 1m side)
Prevents you from counting the pebble on the table as part of the table (not of same material and won't follow)
It also allows you to count pebbles in a bag as one.

ocdscale
2009-12-04, 02:16 PM
Have any continuous object count as 1 object.
- Any body that is made of the same material in contact counts as continuous (eg. water in a lake is continuous, sand on a beach is continuous)
- If two points on the body that will follow when the other is moved, the body is continuous between those two points (rigid bodies are continuous, glued bodies are continuous, cloth is continuous, so is jelly)


If I understand the first part correctly:
A handful of sand is one object. Put a grain of rice and it is now two objects. Strange, but not really game breaking. It sounds like your rules could work well.

But one way to avoid these object problems is to move away from an object oriented approach. What about changing the approach from "TK can affect objects. This is what an object is.." to "TK can act at a distance. This is how it can act..."

A question about how you are using TK: How hard should it be for someone to use it to unscrew the top of a soda bottle? Or to use your example, how about peeling an orange?

If you want these tasks to be relatively hard, the easiest action for TK is just being able to project force at a distance. You can push, pull and lift things fairly easily (depending on the mass), because that just involves applying a single force in a single direction. Pushing a cart full of apples is pretty simple, apply a force to the rear end of the cart.

But even simple manipulation can be difficult because you need to apply different forces from different directions. (unscrewing a bottle cap requires a firm "grip" on the cap and the bottle, and a way to apply a 'twisting' force).

If you want those kinds actions to be relatively easy, the 'hand of force' concept is easiest way to describe how TK acts.

You can use the 'hand of force' at even a basic level. Beginner level TK can't manipulate the hand with any level of dexterity, all it's really good for is projecting force (pushing, then lifting, then pulling). Later they learn how to 'cup' (to hold sand/water in the air), then grip, etc. At some point they get beyond what a single human hand can do and are able to project the force equivalent of multiple hands or non-human hands (tentacles/ropes of force/etc).

Hashmir
2009-12-04, 02:37 PM
One quick way to dodge the sand problem is to declare that an "object" is an entity defined by mystical rules of the universe -- rules which just so happen to line up with standard human perceptions.

In this case, it is immediately obvious that the grain of sand and the table are separate objects, and it allows you to blast a hole in the beach, because the beach is the object. It also lets you define a "person" as a distinct object, but also a "nose" or "hand," and you don't have to ponder where the hand truly ends.

Many fantasy writers do this kind of thing, because it's the easiest way to make the rules match our perceptions: You simply declare that our perceptions arise from the rules. Just yesterday, in fact, I was reading a Dresden Files book that used this to declare thunderstorms as a source of great magical power.

jseah
2009-12-04, 06:23 PM
One quick way to dodge the sand problem is to declare that an "object" is an entity defined by mystical rules of the universe -- rules which just so happen to line up with standard human perceptions.
There is that, but see the response to the next one.


But one way to avoid these object problems is to move away from an object oriented approach. What about changing the approach from "TK can affect objects. This is what an object is.." to "TK can act at a distance. This is how it can act..."
The point of using an object oriented approach was to simplify calculations.
The various variations on how TK acts is all good. I have those.

I still need an object oriented approach since lots of things refer to "1 object" and stuff gets horribly complicated if I take away the "1 object" target. Volume based stuff is never really very nice.


If I understand the first part correctly:
A handful of sand is one object. Put a grain of rice and it is now two objects. Strange, but not really game breaking. It sounds like your rules could work well.
Hmm... should a grain of rice count as part of the handful of sand? Never struck me that it should.

Well, if it's in a bowl, then the whole thing, bowl, sand and rice, all count as one through the "follow" criteria.
I realize this makes the "world" count as one object, which then subdivides into 1m^3 blocks or less. That seems fine.

Still, it does make a mixture of black and white sand count as a million different objects. Which is irritating.

This is getting complicated enough that I'm considering just flipping into a volume-based approach and have TK be a force-field over the volume defined by caster.

Mando Knight
2009-12-04, 06:40 PM
1. A continuous solid body.
Continuous being defined as, "if I pick it up on one point, if the other point follows it, they're continuous between those two points".

Problem: bendy things don't qualify (depending on how rigorous your definition is). And separating glued objects becomes impossible (since you can't target the two halves separately)
The first isn't a definition of continuity, it's the definition of rigidity. Continuity requires a consistent presence of the object over the area of inspection.

2. Caster-defined volume
Caster defines a set volume and says "this is one object"

Problem: Unsure how to distribute force over the volume, could waste a lot of power on 'wind'
Also causes apples to fly out of a cart when you push the whole thing
If you're not good at it, then that's what'll happen when you create a pushing force on the cart. If you can correctly gauge how stable the apples in the cart are, you can move the cart without a problem.

jseah
2009-12-04, 07:06 PM
The first isn't a definition of continuity, it's the definition of rigidity. Continuity requires a consistent presence of the object over the area of inspection.

If you're not good at it, then that's what'll happen when you create a pushing force on the cart. If you can correctly gauge how stable the apples in the cart are, you can move the cart without a problem.
Yes, well, the two have now been made a little more rigorous. Although I appreciate that it's buried in a wall of text.

I'll edit the thread's first post.

dspeyer
2009-12-04, 10:18 PM
An alternate approach: an object is a manifestation of a single platonic form. Therefore a beach is an object, and a grain of sand is an object, but a grain of sand on a table is not an object because there is no perfect grain-of-sand-on-table.

Sir_Elderberry
2009-12-04, 11:51 PM
An alternate approach: an object is a manifestation of a single platonic form. Therefore a beach is an object, and a grain of sand is an object, but a grain of sand on a table is not an object because there is no perfect grain-of-sand-on-table.

Doesn't the fact that I can picture a grain of sand on a table, and recognize grains of sands on tables as such despite superficial physical differences, mean that it exists as a concept, and I must therefore be recalling the Form of Grains of Sand on Tables? (Sorry, I'm not really that up on Plato)

rockdeworld
2009-12-05, 01:41 AM
Dictionary.com definition of an object: Anything that is visible or tangible and is relatively stable in form.

I haven't seen an explicit definition in the d20srd, but it seems to implicitly define objects as not creatures, i.e. in the Armor Class section:

Armor Class
Objects are easier to hit than creatures because they usually don’t move, but many are tough enough to shrug off some damage from each blow. An object’s Armor Class is equal to 10 + its size modifier + its Dexterity modifier. An inanimate object has not only a Dexterity of 0 (-5 penalty to AC), but also an additional -2 penalty to its AC.

To answer your questions:

General problems:
Composite materials are tricky to handle. Liquids and gases are worse.
IE. does each grain of sand on the beach count as separate objects?
Let's say we cast disintegrate (D&D 3.5) on the beach. One grain of sand, or a big hole?
Take the one grain of sand, and place it on a clean table. Disintegrate that, and if you hit it, I have no doubt that many people will agree the table doesn't disappear as well.
Double standard? I dislike those.
Read the spell description:

When used against an object, the ray simply disintegrates as much as one 10-foot cube of nonliving matter.
Table? Gone. Beach? Gone (at least in a 10-foot cube).


Have any continuous object count as 1 object.
- Any body that is made of the same material in contact counts as continuous (eg. water in a lake is continuous, sand on a beach is continuous)
- If two points on the body that will follow when the other is moved, the body is continuous between those two points (rigid bodies are continuous, glued bodies are continuous, cloth is continuous, so is jelly)
Simple solution: only solids are objects (this also seems to be implicitly assumed by the d20srd)


For TK, any object that weighs over 1 kilogram or is larger than 1m^3 is divided into sub-objects.
These sub-objects are targeted as one object each and must be less than 1 kilogram.
The shape is caster-defined but must be contiguous, convex and fit in a cube (1m side). The block is allowed to extend out of an object but will not take anything outside as part of the sub-object.
Use the method of division that gives the least number of sub-objects. All variations in that method are allowed, caster chooses one.
I don't like this definition, because Mage Hand would be able to decapitate people by moving their head up 15 feet.

To sum up the argument: Use common sense when defining objects (and read spell descriptions thoroughly.)

jseah
2009-12-05, 04:45 AM
Table? Gone. Beach? Gone (at least in a 10-foot cube).
The thing about this is that are you counting the beach as one object or each grain of sand as one object?
How big do the sand grains have to get before you start counting them as individuals? stones? pebbles? boulders?!

I'm sure you agree that disintegrating the table won't affect the floor the table is on. Then it's just the same problem but a matter of size.

You imply that there is a minimum size by which "objectness" cannot propagate through. Am I right in reading it that way?


Simple solution: only solids are objects (this also seems to be implicitly assumed by the d20srd)
Oh. So TK can't target liquids?

I'm perfectly certain that TK should be able to cause a wind or current if desired.


I don't like this definition, because Mage Hand would be able to decapitate people by moving their head up 15 feet.
Mage Hand would also need to exert enough force to remove your head.

Which is not possible without an anchor point since people's heads are perfectly able to support the rest of the body.

With two TK spells, sure, you can try. That's like taking two large "hands" and breaking the target in half. I WANT TK to be able to do that.

Also, this is about a homebrew system, not D&D3.5. It's just that the problem of defining objects carries over.

Johel
2009-12-05, 07:45 AM
Thanks for the suggestions:

Johel: This is a homebrew system, unrelated to D&D, I just used the disintegrate thing to illustrate the problems with user-defined and continuous body.
I appreciate your point that we should use the solid object definition though. How would you apply that to the disintegrate-the-beach problem?

I was mostly thinking "telekinesis", since it was your first question back then.
:smallsmile:

"Disintegrate-the-beach", you mean disintegrate billions of sand grains, right ?
Common sense dictates that we use volume for that one and, as long as the sand grains touch each other, the "disintegrate" effect somehow jumps from one to the next, until a appropriate volume of sand (or whatever is buried in it) is affected.

Of course, that's only what I consider "common sense" and that's a really subjective concept.

Basically :
If the definition of an effect is ambiguous but uses weight, try to solve the problem using weight. If it doesn't work, try with number, then with volume.
If the definition of an effect is ambiguous but uses volume, try to solve the problem using volume. If it doesn't work, try with number, then with weight.
If the definition of an effect is ambiguous and uses neither weight or volume, it probably use number. If it doesn't, then try with Rule of Cool only and pray that your players are mature and reasonable enough.