The "Force" explained

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The "Force" explained

Postby PeterT » Wed Aug 09, 2006 7:18 pm

Perhaps you have seen people talk about "The Force" in the contest threads, or on the official solution page. But what is it? And how do you use it? I'll try to answer these questions here.

Overview
"The Force" is a collective term for mechanisms that use a bug in the physics engine to generate momentum without using tension or other "realistic" means.

History
The first time the force was publicised was by BFC in a solution to Contest #1. He made a rotating "paddle" that accelerated indefinitely (or, rather, until it breaks) without any outside influence. It was soon discovered that the paddle could be simplified by just using 3 metal bars instead of 4. This version is pictured and described below.
Since then, the force has also been used with rubber and metal sheets to create rotating wheels and machines. One of the most impressive examples of "Force" usage is the "Force Clockwork" level, also pictured below. A longer and even more powerful paddle has also been developed.

How does it work?
The "Force" is generated when the ending point of a piece of material intersects another piece that exists on the same plane (ie. a metal bar and metal sheet combination will never produce any force). This happens in area 1 marked with the red circle in the picture below.
The physics engine tries to resolve this situation by moving the endpoint of the metal bar to the left. This movement propagates to point 2, which follows. It in turn affects point 3. Thus, the situation never gets resolved and the paddle starts its rotation.
Depending on the initial depth of the interpenetration and the overall structure of the paddle, the acceleration will vary. Some panels will continue to accelerate until they self-destruct after 2 or 3 full rotations.

Please ask further questions related to "The Force" in this thread.
Attachments
paddle2.jpg
The more powerful / longer paddle variant (from my solution to contest 7).
clockwork.jpg
The "Force Clockwork" level by Stevez.
classicpaddle.png
The classic paddle with explanatory markings.
classicpaddle.png (13.15 KiB) Viewed 29245 times
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Postby dudiobugtron » Wed Aug 09, 2006 11:29 pm

Thanks for posting this Peter, I remember when I joined the forums and everyone was talking about the force, it was pretty bewildering!!!
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Postby kingofthespill » Fri Aug 11, 2006 12:55 am

Great pictures :!: I think one general way of describing it is any unrealistic forces due to material interactions or collisions.
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Postby dudiobugtron » Fri Aug 11, 2006 3:22 am

kingofthespill wrote:Great pictures :!: I think one general way of describing it is any unrealistic forces due to material interactions or collisions.

I think the 'snake charming' rope trick* fits into this definition but it should be distinct from 'the force'.

Also the force which is generated when metal reaches it's break point, causing it to completely disintegrate, is rather unrealisitc too!


*the one where rope can support metal plates or cloth vetically upwards, if aligned correctly.
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Postby Skrying » Fri Aug 11, 2006 9:58 am

Nice, I'm sure it'll help those who are knew to the game.

I'm a fan of the force in a way. Though I rather not see it used in contests, I do like seeing it used in custom made levels. I've personally had a lot of fun creating experiments based around it, using it to move objects or create odd motions.

I've created anti force and counter force devices that exploit the force of force and use elastic to basically throw the force the other way. Its interesting to see. I've achieved my highest spinning speeds when using reverse force setups.

Rubber is another area were the force can be extremely entertaining. You can basically make a square the will wiggle around. Very fun!
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Postby Robmonster » Mon Aug 14, 2006 10:22 am

Is there a download link for the Force Clockwork level anywhere?

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Postby Lazerus » Tue Aug 15, 2006 2:16 am

Robmonster wrote:Is there a download link for the Force Clockwork level anywhere?

RM


Check the "New Levels" Section of the website!
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Postby kingofthespill » Wed Aug 16, 2006 8:07 pm

Here is an example of force that leads to welding:
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bob's_catcher.gif
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Postby JP » Tue Sep 19, 2006 12:31 am

I've been playing around with a slightly different paddle design. It's not all that powerful so it takes a couple of spins to get up to speed, but it's only $40...
Attachments
Level 2 - Mind the gap.JP_160.lvl
Level 2 solution example
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paddle.JPG
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Postby kingofthespill » Tue Sep 19, 2006 6:24 am

Impressive!
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Postby Vendetta » Wed Sep 27, 2006 4:13 am

ive found it odd, that if i place a metal bar not long enough to mess up the metal swinging around, it makes the paddle swing faster. i cant describe it well, just look at the screenie, then try it yourself.


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Postby dudiobugtron » Wed Sep 27, 2006 5:07 am

It's because (even though it shouldn't), attaching something to an 'anchor point' does have an affect on the other things attached to the anchor point.

This causes numerous problems in levels where the start 'mechanism' and the end mechanism need to be attached to the same anchor point! Becuase once the armadillo gets to the end, and you start buidling it, it mucks up how the things at the start work.
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Postby Samip » Sat Sep 30, 2006 4:20 pm

nvm
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Postby Muffenz » Sun Oct 01, 2006 4:35 am

that seems really hard to make... Any easer way to make it?
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Postby dudiobugtron » Wed Nov 08, 2006 1:24 am

I can't figure out how to sticky this so I'll just bump it! :D
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