Mote absorbing mechanics

Feedback and support for the PC version of Osmos
Catinthewall
Posts: 13
Joined: Mon Aug 17, 2009 7:55 pm

Mote absorbing mechanics

Postby Catinthewall » Tue Aug 18, 2009 7:57 pm

I've been playing around, and I've notices a bit of an odd quirk in the system. If you want to absorb a stationary mote, It's completely absorbed by you by the time you pass the original center of the prey. At that point, you should have only absorbed 3/4s of the mote, leaving the remaining quarter as a mote whose diameter has halved. As it is, close calls greatly favor the larger mote. if he grazes a percentage of the radius, it's as if he grazed twice as much as he really earned. To put it in photoshop terms, the anchor point of the scaling should be on the opposite edge, not the center.

And now a little math/logic problem. Mote x has an area of 100, Mote y has an area of 50. they are both moving at the same speed in opposite directions, and collide. How fast is the new mote moving? Logically, its speed should be half the original. EDIT: I meant one third. Half the velocity is lost, and the mass is increased by 50%.
All well and good so far.
Now, suppose it only just grazes the edge, and mote x grows to an area of 125. In the pure world of osmos, the speed drops to 75% the original speed. On closer examination, this doesn't quite fit, for a variety of reasons. EDIT: Same thing. one quarter of the velocity is lost, and the mass is increased by one quarter. If I'm not mistaken, that's 60%. I may be wrong, I'm rusty.
Firstly, the grazed off mass doesn't automatically lose it's velocity. Imagine it as a minimote inside the macromote. Most of it is moving one way, but 20% of it wants to move the other way, and it's all on the edge. I'm just assuming that motes won't undergo mitosis in any circumstances, so the result is a brief time where the mote is in an inhomogeneous state. The result of this is something this game is completely lacking in. SPIN!
The second issue is another aspect completely ignored. Friction. If I set up the above grazing experiment, No matter what the base speed is, the results would be the same. But logically, the slower I make the test speed, the more speed would be lost, percentage wise. Why? because the two motes would be in contact for more time, so the more friction is built up. This would also cause spin.
Gameplay-wise, I can see the reason for a lack of friction in the mote's gliding, no stable orbits. I can live with that, I'll just imagine it's an alien biome based in liquid helium. It does suggest the need for different biomes for when you get around to the sandbox mode.

Finally, if two motes of the exact same size touch, what happens?
Last edited by Catinthewall on Tue Aug 18, 2009 8:28 pm, edited 1 time in total.

kajaco2
Posts: 6
Joined: Sun Aug 16, 2009 6:56 pm

Re: Mote absorbing mechanics

Postby kajaco2 » Tue Aug 18, 2009 8:28 pm

Catinthewall wrote:And now a little math/logic problem. Mote x has an area of 100, Mote y has an area of 50. they are both moving at the same speed in opposite directions, and collide. How fast is the new mote moving? Logically, its speed should be half the original.


I don't think this is quite right. The mass times acceleration of the two motes before the collision is equal to the mass times acceleration of the new mote z resulting from the collision (F=mx*ax - my*ay = Fz = mz*az). I assume motes have the same density, so area is indicative of mass, and mx = 2my; mz = 3my. Further, ax = ay (except for direction, thus the negative sign in the Force equation). Substituting into mx*ax - my*ay = mz*az gives (2my - my)ax = 3my*az; my*ax = 3my*az; ax/3 = az. Thus the acceleration of the new mote will be one-third that of the original mote and will be in the same direction as the larger of the original motes.

But it's late for me and it's been a while since I had physics, so I might be missing something. :geek:

Catinthewall
Posts: 13
Joined: Mon Aug 17, 2009 7:55 pm

Re: Mote absorbing mechanics

Postby Catinthewall » Tue Aug 18, 2009 8:30 pm

Yeah, I just realized that as I was getting to sleep. check the edits. :oops:

ryandaniels
Posts: 22
Joined: Fri Mar 20, 2009 8:55 pm

Re: Mote absorbing mechanics

Postby ryandaniels » Tue Aug 18, 2009 8:52 pm

It's a game guys :D

ryandaniels
Posts: 22
Joined: Fri Mar 20, 2009 8:55 pm

Re: Mote absorbing mechanics

Postby ryandaniels » Tue Aug 18, 2009 8:58 pm

Catinthewall wrote:Finally, if two motes of the exact same size touch, what happens?


Well it's close to impossible if they are using floating point variables for sizes, but in any case, it depends on whether they used

if(more1>= mote2)

or

if(mote1<= mote2)

There's also the very unlikely possibility that they used

if(mote1> mote2)

or

if(mote1< mote2)

in which case the program would skip the if block and enter the else block (assuming there is one), which would cause some interesting errors shortly followed by the game crashing. :o

saaaammmmm
Posts: 3
Joined: Tue Aug 18, 2009 9:58 pm

Re: Mote absorbing mechanics

Postby saaaammmmm » Tue Aug 18, 2009 10:25 pm

What we learned as children, that one plus one equals two, we know to be false. One plus one equals one. We even have a word for when you plus another equals one. That word… is love.

spamalot
Posts: 9
Joined: Wed Aug 19, 2009 1:20 pm

Re: Mote absorbing mechanics

Postby spamalot » Wed Aug 19, 2009 1:55 pm

I noticed that vector addition for two motes melting isn't quite as I had expected.

Say you hit a mote head-on: it will get a backwards velocity.
Now if you hit a mote just barely: it will get a backwards velocity.

That's not quite correct as firstly it should have an equivalent new velocty to the angle it was hit at (now don't ask me what that would be - all I can say is that it wouldn't be straight backwards), and secondly you might consider adding rotation to add a further level of depth to the game.

The little nerd in my head keeps thinking of rotating neuron stars or black holes in space... if you can make the motes spin, the gravitational center of a map would get a huge spin that you could at some point dissolve into some kind of explosion with new motes ripping out of the center mote. This could create a balance system that draws mass in and throws it out again at intervals.

Also motes colliding at high speeds but not hitting straight on could then partially melt and separate again. (Wasn't this how our moon was formed?).


Just a few goodnight thoughts. Would love to hear your thoughts about this.


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