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JM_MD18

GRANULAR

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I'm just getting started with X-P4 and I'm trying to re-create Bob's snow/sand (+- 12 minutes mark) scene but I can't figure that out.
What are the values (+-) for sand or snow and xpFluidfx?

Also why sometimes the generated particles look like they are loosing their volume or deflate if you will?

Thanks in advance! and you all have a fantastic 2019

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Yes me too! I wrote a post on the old forum just before it got updated to say the same thing.

As soon as I apply gravity, it just crushes the granular structure. I can't find a sweet spot that lets an object (e.g. a snow ball) break apart on impact, and have gravity, as the gravity destroys it. I was playing around for nearly 2 days, trying every normal and extreme combination of density, viscosity, cohesion and stability.

Very simple scene attached.

OV_snowball.c4d

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On 1/4/2019 at 12:33 PM, ollyvenning said:

Yes me too! I wrote a post on the old forum just before it got updated to say the same thing.

As soon as I apply gravity, it just crushes the granular structure. I can't find a sweet spot that lets an object (e.g. a snow ball) break apart on impact, and have gravity, as the gravity destroys it. I was playing around for nearly 2 days, trying every normal and extreme combination of density, viscosity, cohesion and stability.

Very simple scene attached.

OV_snowball.c4d

I don't have problems with gravity.
I have tried emission shot mode as well as the hexagon.

Same here > combination of density, viscosity, cohesion and stability and nothing.

I try even to match the number of particles to start from there. Bob's saying 50.000 so that's what I did.

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I think the problem ollyvenning is addressing is still persistent . But I´m afraid that´s just nature of the beast and no way out.

Just level out your collider cube and place it right below the emitter and you´ll see, the snowball is falling apart immediately, though there is no additional energy obtained by falling. Gravity provides energy enough to do so.

So if you want to keep a structure like wet sand or snow intact, you´ll have to use no or low  gravity and switch to normal as soon as there is an additional impact you want to fall this thing apart in a natural snow like manner as you would expect.

 

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On 1/4/2019 at 3:16 PM, ollyvenning said:

Hi Mike, yes I did indeed try that. Gravity still destroys it!

I forgot to mention that I have had the same problem before which I solved changing the particles radius.
Maybe that helps.

 

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I gotta work on a SALT sim.

I tried to use Cycles 4D and its Cyinstance tag decreasing the scale but obviously this approach leaves gaps between the particles .

Is decreasing the particles radius the only way to achieve the table salt appearance?


granular_render_test01_radious-1.thumb.jpg.7c30c378aa3a867219357c8de511ebbe.jpg

 

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4 hours ago, Lothar said:

I think the problem ollyvenning is addressing is still persistent . But I´m afraid that´s just nature of the beast and no way out.

Just level out your collider cube and place it right below the emitter and you´ll see, the snowball is falling apart immediately, though there is no additional energy obtained by falling. Gravity provides energy enough to do so.

So if you want to keep a structure like wet sand or snow intact, you´ll have to use no or low  gravity and switch to normal as soon as there is an additional impact you want to fall this thing apart in a natural snow like manner as you would expect.

 

 

5 hours ago, Mike Batchelor said:

Hi, I have tweaked your file added a new emitter and default gravity. this should help you get into Grains. ill post it on Discord too.

P9E83Cp.gif

OV_snowball_02.c4d

Thanks, MIke. From looking at your settings, it seems the major difference was the friction settings. I didn't appreciate such a high setting would have that binding effect. Thanks for your help!

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4 hours ago, Lothar said:

I think the problem ollyvenning is addressing is still persistent . But I´m afraid that´s just nature of the beast and no way out.

Just level out your collider cube and place it right below the emitter and you´ll see, the snowball is falling apart immediately, though there is no additional energy obtained by falling. Gravity provides energy enough to do so.

So if you want to keep a structure like wet sand or snow intact, you´ll have to use no or low  gravity and switch to normal as soon as there is an additional impact you want to fall this thing apart in a natural snow like manner as you would expect.

 

Yes, I haven't been able to get that setting right, e.g. the base of a snowman, that is already static, and then can crumble away. I have done some tests using Q&As to turn gravity on when particle speed >10 (or whatever speed suitable) - that yields OK results, but it's not really quite right!

It seems that upping the friction really helps, but I figure that if it is possible to do the static snowman base/lump of kinetic snad it's gotta be a real sweet spot. I'll fiddle some more!

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