Universe Sandbox

Universe Sandbox => Universe Sandbox | Discussion => Topic started by: Greenleaf on June 16, 2014, 04:52:01 PM

Title: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: Greenleaf on June 16, 2014, 04:52:01 PM
A longer collision test which shows the (current) gradual collision mode. Here grazing collisions are supported, where only part of the momentum and mass is being transferred.
It is shown how orbital angular momentum through collisions is converted into spin angular momentum, and it is seen how an impactor can lose some of its mass and fly on.


http://youtu.be/1ZQhxae0lMA


I will try to sometimes record things when I test, both to show you and for personal reference.
Videos will be online at https://www.youtube.com/user/GreenleafDevelopment
and I believe Chad will put things online on his channel as well,
which is https://www.youtube.com/user/cloud07studios


I mention this because there might not always be a forum post about it, and there was a lot of confusion about one such video yesterday.
Title: Re: Extended collision video
Post by: WitheHole18 on June 17, 2014, 06:29:27 AM
Ok thanks for the info and for clarification.
Interesting video!
Title: Re: Extended collision video
Post by: gabriel.dac on June 17, 2014, 07:39:50 AM
At 3:00 you show the gradual transfer of energy and momentum. Cool. But uhh...  Is that really how things would happen in real life? Would the planet really keep bouncing around Earth like that?
Title: Re: Extended collision video
Post by: JAW1002 on June 17, 2014, 08:00:46 AM
I reckon those kinda impacts would shatter the earth's crust, the cooling lava wouldn't leave any trace of the continents from before the impact, instead a completely new looking planet.
Title: Re: Extended collision video
Post by: Greenleaf on June 17, 2014, 08:24:25 AM
At 3:00 you show the gradual transfer of energy and momentum. Cool. But uhh...  Is that really how things would happen in real life? Would the planet really keep bouncing around Earth like that?


Nope. That is not how it would happen. There are several issues with this. One is that the force opposing sliding, which is also imparting torque, is disabled pending bug fixing. With this force you would see the mars dig down a little, lose much more velocity and start rotating (tilting forward). Another is that the planets remain spheres.

We consider three modes of collision in the same simulation framework, which are instant combine collisions, for things which are out of sight or which happen too fast to notice, gradual collisions for things you do see, but perhaps don't have up right in front of you and then SPH for things you really care about watching.

A more realistic, and somewhat unexciting, example is seen in these two videos.
Please do keep in mind that videos posted by us are generally in response to interest in seeing the current state of development, a little before you can see it yourself in the next release. They do not represent the final product, but only a step on the road.

Comments and questions are very welcome. Just expect the general answer to be "we know, and we plan to handle it in due time". ;-)

http://youtu.be/9w1din9uV68


and in the end
http://youtu.be/-rYWl2Wb7v4





Title: Re: Extended collision video
Post by: Greenleaf on June 17, 2014, 08:26:42 AM
I reckon those kinda impacts would shatter the earth's crust, the cooling lava wouldn't leave any trace of the continents from before the impact, instead a completely new looking planet.


It certainly would. Not only would most material melt or evaporate, but the inside may become the outside. Speaking of craters in such cases makes little sense.
Title: Re: Extended collision video
Post by: gabriel.dac on June 17, 2014, 11:16:38 AM
Comments and questions are very welcome. Just expect the general answer to be "we know, and we plan to handle it in due time". ;-)

That is why I always hesitate when reporting bugs in-game. I always think you are already aware of that :p

I don't know what else to say then, besides the usual "good job!" :)
Title: Re: Extended collision video
Post by: Greenleaf on June 17, 2014, 02:53:05 PM
Comments and questions are very welcome. Just expect the general answer to be "we know, and we plan to handle it in due time". ;-)

That is why I always hesitate when reporting bugs in-game. I always think you are already aware of that :p

I don't know what else to say then, besides the usual "good job!" :)


We are not always aware of it, so don't be put off by that. Keep the comments coming.
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: Dan Dixon on June 19, 2014, 06:40:55 PM
I'm really happy with the direction collisions are headed in Universe Sandbox ... I hope everyone else is too.
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: blotz on June 19, 2014, 07:08:24 PM
as long as they're not heading towards earth, i'm happy
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: Dan Dixon on June 19, 2014, 08:45:22 PM
Collisions with Earth are the cornerstone of our testing. :)
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: Breakfestbacon on June 19, 2014, 09:08:28 PM
Hahaha. That's what I do every time I start the game, collide the earth with some object.
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: WitheHole18 on June 20, 2014, 02:32:42 AM
Hahaha. That's what I do every time I start the game, collide the earth with some object.
Even I do it, who knows why?? :)
With alpha 7 will be even better! ;) :)
Title: Re: Extended Collision Demonstration of the new Collision System in Alpha 7
Post by: gabriel.dac on June 20, 2014, 09:48:51 AM
Collisions with Earth are the cornerstone of our testing. :)

not nice but lots of fun