Poll

How would you prefer to have collisions work?

As it is with 2.36.1. No bounces. Collisions just conserve momentum.
5 (55.6%)
As with older systems. Loads of bouncing! No attempt to conserve momentum. Just a repulsion field.
0 (0%)
Variable bounce rates (repulsion fields) controllable from the options screen.
0 (0%)
Combination of repulsion fields and conservation of momentum controllable from options screen.
4 (44.4%)

Total Members Voted: 9

Author Topic: Collisions  (Read 4731 times)

Offline PurpleYouko

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« on: April 03, 2005, 12:15:44 PM »
I have a few ideas about how this could become controllable from the options screen. just haven't had the time to implement them yet.
Please add comments about the way you would prefer it to work.
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Offline shvarz

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« Reply #1 on: April 03, 2005, 02:19:15 PM »
I am not too fond of bounces.  But other people might.  I say "no bounces" by default and allow bounces somewhere deep inside "advanced options".
"Never underestimate the power of stupid things in big numbers" - Serious Sam

Offline Numsgil

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« Reply #2 on: April 03, 2005, 06:16:12 PM »
Technically I'd like to try out a system of 0 momentum like schvarz suggested a while ago.  That would be as simple as fixing friction rates and then setting them incredibly high.

I would like a slider between 100% elastic collisions and 100% 'sticky' collisions.  That'd be ideal.

Offline PurpleYouko

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« Reply #3 on: April 04, 2005, 09:35:56 AM »
Friction is fixed in the physics code that I sent you. Should work fine now.
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Offline Botsareus

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« Reply #4 on: April 04, 2005, 12:50:25 PM »
I am all in stuff like bounces.... I like that stuff , its kool

Offline Zelos

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« Reply #5 on: April 04, 2005, 02:13:59 PM »
I think we shall use physical things. im more of the reallity guy. the momentum in a system is always 0
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Offline PurpleYouko

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« Reply #6 on: April 04, 2005, 03:32:19 PM »
Quote
the momentum in a system is always 0
How does that work then?
If the system is closed then no energy can go in or out. But even then the momentum (or KE) can be converted to heat or light or back to KE.

If you have zero momentum then you must also have zero motion.

Or are you saying that the net change in momentum during a collision is always zero? Meaning that the total momentum for both robots is the same both before and after the collision.

Again this only applies to an idealized system where no energy can be converted to any other forms. Doesn't happen in real life situations as a certain amount of momentum is always converted to a different form of energy such as heat, light or sound.

([span style=\'font-size:8pt;line-height:100%\']For simplicity's sake momentum and kinetic energy are assumed to be the same[/span])
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Offline Botsareus

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« Reply #7 on: April 04, 2005, 03:52:51 PM »
who here plays tabel pool? How can I get dbs to behave like that when they collide?


2nd qustion: Was the exselaration messed up too?
« Last Edit: April 04, 2005, 03:54:28 PM by Botsareus »

Offline Zelos

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« Reply #8 on: April 04, 2005, 04:03:55 PM »
it worx coz momentum cant be converted to any energy form. its kenetic energy that can. if I throw something in space at one direction, my body gets movementum in the other direction, which would be - compared to the thing I throw. if it have 5 as momentum, then I get 5 momentum in the other direction. so it becomes like 5-5=0. still 0 momentum. no matter what you do, it will always be 0
and PY, ure 42, right?, you should know better than thinking momentum and kenetic energy are the same, its completly different thing
« Last Edit: April 04, 2005, 04:04:48 PM by zelos »
When I have the eclipse cannon under my control there is nothing that can stop me from ruling the world. And I wont stop there. I will never stop conquering worlds through the universe. All the worlds in the universe will belong to me. All the species in on them will be my slaves. THE ENIRE UNIVERSE WILL BELONG TO ME AND EVERYTHING IN IT :evil: AND THERE IS NOTHING ANYONE OF you CAN DO TO STOP ME. HAHAHAHAHAHAHAHA

Offline Numsgil

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« Reply #9 on: April 04, 2005, 04:05:56 PM »
If you don't like sticky collisions Bots, what did you vote for?  Shouldn't your vote be for the 2nd choice?

In reality either collisions system hardly effects the bots at all.  Most good bots will probably either bump veggies along in front of them or never touch them at all.

Offline Numsgil

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« Reply #10 on: April 04, 2005, 04:09:07 PM »
Quote
it worx coz momentum cant be converted to any energy form. its kenetic energy that can. if I throw something in space at one direction, my body gets movementum in the other direction, which would be - compared to the thing I throw. if it have 5 as momentum, then I get 5 momentum in the other direction. so it becomes like 5-5=0. still 0 momentum. no matter what you do, it will always be 0
and PY, ure 42, right?, you should know better than thinking momentum and kenetic energy are the same, its completly different thing
Uh, Zelos, I think you're a little confused.

Momentum is mass times velocity.  In your example, you're assuming you started with 0 velocity, so when you throw the end system still has 0 momentum.

But if you throw something when you're already going 3 m/s then the end momentum and the beginning momentum aren't 0.

I don't think PY was saying that momentum and KE are the same thing.  Just that sometimes KE (and thus momentum) are converted into heat, light, explosions, etc. in some collisions.

That is, not all collisions conserve KE perfectly.

Offline Botsareus

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« Reply #11 on: April 04, 2005, 04:09:18 PM »
I did not say I want no energy loss during movment. Friction etc. is all good ideas, thats why I voted for choise 4

Offline Botsareus

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« Reply #12 on: April 04, 2005, 04:14:43 PM »
But if the new legues will use this new , slow , collisions ,then I have no choise , I will use them too.

Offline Numsgil

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« Reply #13 on: April 04, 2005, 04:26:06 PM »
What do you mean by 'slow' collisions.  Mostly what happens now is that bots won't bounce off each other.  They'll either kind of stick together or do this:

O>.....0   -> O0 -> O.... 0>

Where > denotes motion.

Offline PurpleYouko

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« Reply #14 on: April 04, 2005, 04:32:54 PM »
Quote
and PY, ure 42, right?, you should know better than thinking momentum and kenetic energy are the same, its completly different thing

Where did I say they were the same thing?

Momentum is Mass times velocity
Kinetic Energy is 1/2 MV squared

Whoopdy bloody do!

What I said was
Quote
(For simplicity's sake momentum and kinetic energy are assumed to be the same)
That just means that is a shit load easier to discuss and explain things in terms of conservation of momentum that it is to bring KE into the conversation.

And NO! Momentum most certainly does not alway equal zero!
Try throwing a ball at a wall covered in soft plaster.

Try this calculation for size!

Before collision
Ball velocity = 20
Ball mass = 10
Ball Momentum = MV = 200

Wall mass = about 20,000
Wall velocity = 0
Wall momentum = 0

Collision!!!!!!!!!
!!!!!!SPLAT!!!!!!!
Ball sticks in soggy plaster

Ball velocity now zero
Ball momentum now zero
Wall velocity OOH Look It's still ZERO
Wall momentum is STILL ZERO

Where did your momentum go?

Well neither the wall or the ball are moving any more so IT ISN'T THERE ANY MORE

Why?

Because the kinetic energy of the ball was absorbed by the plaster and used up completely in reshaping it from a nice flat surface into a big sodding dent!

KE and momentum may not use the same calculation but they are very similar in nature. Both can be imparted or absorbed by other features in any system and DO NOT ALWAYS EQUAL ZERO. In fact the only time when momentum in a system can actually be zero is when that entire system has reached maximum entropy.

That is just basic physics.
There are 10 kinds of people in the world

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