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Creating realistic physics


LynValentine
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I bought physics in the marketplace that make the breasts "react" to gravity (if you lay on the left side the breasts will move to the left, if you lay on the right side they will move to the right and so on) and you can edit these physics to your liking.

 

But editing physics is a hit and miss game (more misses than hits actually) if you don't exactly know what each option does and some options seem to have no effect at all or you can't see the effect so easy.

For example i have a top with straps in the middle but no support under the breasts which means the breasts should be able to move up and down, but they should not be able to move away from each other. And of course they would be able to move to the left and right together. With this top i can't wear a bra physics (that looks wrong with such a top) and nude physics are also wrong because the breasts move more than they should be able.

That is why i thought i should create my own physics using the one from the marketplace as the base (because of the "gravity" effect) to create a realistic look with different tops, but if you don't know exactly what you are doing this is rather frustrating.

Can someone explain to me what the different options in the build menu of a physics exactly do? And is that what i plan even possible?

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6 minutes ago, LynValentine said:

I bought physics in the marketplace that make the breasts "react" to gravity (if you lay on the left side the breasts will move to the left, if you lay on the right side they will move to the right and so on) and you can edit these physics to your liking.

 

But editing physics is a hit and miss game (more misses than hits actually) if you don't exactly know what each option does and some options seem to have no effect at all or you can't see the effect so easy.

For example i have a top with straps in the middle but no support under the breasts which means the breasts should be able to move up and down, but they should not be able to move away from each other. And of course they would be able to move to the left and right together. With this top i can't wear a bra physics (that looks wrong with such a top) and nude physics are also wrong because the breasts move more than they should be able.

That is why i thought i should create my own physics using the one from the marketplace as the base (because of the "gravity" effect) to create a realistic look with different tops, but if you don't know exactly what you are doing this is rather frustrating.

Can someone explain to me what the different options in the build menu of a physics exactly do? And is that what i plan even possible?

I'm eager to learn the mysteries of physics...can't have my boobs flying around like two squirrels inside a pillow case fighting for an acorn...

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Oh... this gets tricky. I think most of us learn by experimenting.

The technicalities come from how a 3D world works. So know that the strap between the breasts is NOT a strap. It is a mathematical representation of a strap that is likely tied to the avatar body (rigged). The strap has no affect on the body. The movement of the skeleton controls the movement of the body and all rigged attachments. Neither the body nor the strap know about each other nor do they affect one another.

We have clothes and attachments that are made specifically for various bodies. What that means is the vertices of that specific attachment have been set to use the same settings/parameters as the body. This gives the APPEARANCE of clothes/attachments moving with the body as the body's vertices and clothes/attachments' move in parallel. Both following the skeleton at the same speed.

You can find a point by point description here: https://wiki.firestormviewer.org/firestorm_avatar_physics

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1 hour ago, LynValentine said:

For example i have a top with straps in the middle but no support under the breasts which means the breasts should be able to move up and down, but they should not be able to move away from each other. And of course they would be able to move to the left and right together. With this top i can't wear a bra physics (that looks wrong with such a top) and nude physics are also wrong because the breasts move more than they should be able.

That is why i thought i should create my own physics using the one from the marketplace as the base (because of the "gravity" effect) to create a realistic look with different tops, but if you don't know exactly what you are doing this is rather frustrating.

Can someone explain to me what the different options in the build menu of a physics exactly do? And is that what i plan even possible?

Yes it is.  There's three main settings; Bounce (they go up and down), Sway (they go side to side, together) and Cleavage (they go side to side in opposite directions). So for that top you're wearing, you want the numbers to be higher in Bounce and Sway, but zero in Cleavage.  Damping should be low (too much and they'll bounce once or twice then stop abruptly) and Gain should also be low (too much and they'll bounce for hours).  I generally have the Effect set at around 15-20 (you may want this a bit higher if your breasts are bigger than mine) with Gain and Damping around 6-10.

Gravity is in the Advanced Parameters at the bottom, as well as Mass. To get the effect of the breasts reacting naturally (for example laying on your side) both of these should be higher. 

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Ok, lets see if i have understood it right. For a realistic bra physics i would need to set Bounce to a low value (not zero unless you wear a really tight sports bra), Sway to a low value and Cleavage to a very low value (not zero, unless its a tight sports bra). Damping should be higher (since that is exactly what a bra does xD) and Gain should probably be untouched (since the Mass of your breasts won't change).

Is that correct?

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It's been years since I messed with physics sliders. I got them adjust the way I wanted and left them the same since. One thing I do remember that made it harder than it needed to be was that the slider effects were very non-linear, e.g., a slider might increases its effect as it was changed from 0 to 20, but changing it from 20 to 100 had no effect.

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6 hours ago, LynValentine said:

Ok, lets see if i have understood it right. For a realistic bra physics i would need to set Bounce to a low value (not zero unless you wear a really tight sports bra), Sway to a low value and Cleavage to a very low value (not zero, unless its a tight sports bra). Damping should be higher (since that is exactly what a bra does xD) and Gain should probably be untouched (since the Mass of your breasts won't change).

Is that correct?

Well... sort of. Yours is not the most realistic way to think of what you are doing. So I am concerned using that concept of SL boobie bonce will walk you into some problems. Yet, it may work for you.

In a 3D virtual world mass is a parameter fed to the physics engine. The Lindens were designing a physics simulation of how breasts, bellies, and booties bounce. My experience is what you have the avatar doing has more effect... and that reveals a level of inconsistency. So I have a walking physics layer, dancing, and other activities physics layers. I suppose you could make a layer for simulating wearing a bra, no bra, firm or soft breasts...

The idea 'gain' should be untouched is applying a RL concept to something that has no counter part in a virtual simulation. The world is not real. So, gain is just another parameter used to get the result you want. If you get lost in the concepts what you are doing probably will not produce the results you expect.

 

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19 hours ago, LynValentine said:

That is why i thought i should create my own physics using the one from the marketplace as the base (because of the "gravity" effect) to create a realistic look with different tops, but if you don't know exactly what you are doing this is rather frustrating.

Can someone explain to me what the different options in the build menu of a physics exactly do? And is that what i plan even possible?

You absolutely should play around with making your own physics and there is nothing stopping you from creating physics for various activities or outfits types.

It costs nothing to make your own and some other posters have nailed what each setting does. So all there is left is to give it a shot!

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I know its impossible to simulate the RL behavior of any bodypart in SL 100% perfect, because there are so many things that have an influence on the result and some of them can't even be changed so easily. I can only try to make the movement of my breasts look "believable" to myself. Someone with a way slower PC will probably think that my breasts move like i walk on the Moon and someone with a way faster PC might think that my breasts move way too fast. The used mesh body will have an effect too. Before i switched to the Legacy body i used the Freya body and the physics for that body look a bit strange if i use them with the Legacy body (and if you want to have a good laugh try to use one of your physics for a mesh body with your classic (non mesh) body. You will look like your body was made from Jelly xD).

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On 1/9/2022 at 4:59 PM, Charalyne Blackwood said:

I'm eager to learn the mysteries of physics...can't have my boobs flying around like two squirrels inside a pillow case fighting for an acorn...

I'll buy a ticket for that show... 😆

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