POP Grains issues/queries

[sultan]

Hello all,

 

Please have a look at my queries regarding POP Grains:

 

1. Instead of having CG looking particles with symmetry position in initial state when we create GrainSource, have used RandomVolume in GrainSource. But this makes particles chaotic.

So how to make the particles stay random position in initial state ? (or is there any other way to make particles position randomly without blasting as sim progress ?)

 

2. How to make POP Grains stable / still in the initial state with no velocity/force so as to start the sim with rest state and later dynamics act on the triggered particles only ?

(i used POPWrangle to make particles with black color with @v=0.0. But there must be other way as using this technique does not make these particles behave like sand later in sim )

 

3. If you see the below image, you can see that activated particles are passing through other static particles. Have increased Substeps of POPSolver to 10 but still they penetrate through other particles.

So what should be the way to get particles colliding correctly with each other and not pass through ? (This works correctly if the particle count is very less but starts to pass through in high particle count).

 

 

 

4. Have used AttributeTransfer to activate particles and act upon the forces. But how to activate particles randomly in different clumps of area so as to give proper sand drifting at random places ? (For example: Like on a beach as if crabs coming out of sand and how sand falls in the hole created by crabs coming out. So if we take a rectangular flat Cube object and convert it to POPGrains then activate random areas to fall with gravity and those areas increase in size over time so as to give feel of the hole increasing in size. How to achieve this ?)

 

Please have a look at the following file:

PROBLEM_POP-Grains_PassingThrough_v00.hipnc

 

 

 

[tricecold]

1) in the grainsolver turn on jitter scale, so your source will create grains in random positions instead of the grid like position

2) @v = 0.0 will not change their color. v is for velocity, and if you did not bind this to a condition, your particles wont move at all.

3) will check the file for that

4) you can give the particles a random number, and use this attribute to randomize the activation on top of your force attribute. I guess to increase the hole over time, you can literally make a hole under the collision object to let fall off the particles.

[sultan]

1) in the grainsolver turn on jitter scale, so your source will create grains in random positions instead of the grid like position

2) @v = 0.0 will not change their color. v is for velocity, and if you did not bind this to a condition, your particles wont move at all.

3) will check the file for that

4) you can give the particles a random number, and use this attribute to randomize the activation on top of your force attribute. I guess to increase the hole over time, you can literally make a hole under the collision object to let fall off the particles.

 

 

Hi tricecold

 

1). Ok. Will try it

2). @v=0 is for making particles having black color (pre-assigned to them using AttributeTransfer) static. I am not coloring particles using @v=0 (Please check the file).

3). Ok.

4). Making holes in collision object (i.e. floor) does not look controllable & restricts ourselves as later what if we have to make particles fall from other location, then again create a hole , this does not look procedural way of working.

Also, giving random number will not suffice the requirement of "clumps of area" being active at our specific time/frame

Activating with random numbers will only make random particles active anywhere in the sim which is not the requirement & neither controllable

 

Please check the file, you will understand more about my queries.

 

Thanks tricecold

[tricecold]

sorry cant download files at work, had to wait until home,

but as for number 4, you can create sink objects, by holes I meant to remove particles from within the sim, so you give away other particles to keep falling. Its in the file also

 

In the file there is an example file for drifting clumps randomly also, its for particles but will work for grain also same way. you can play with the noise settings to make sharper or softer activation areas etc.

pop_grain_removal.hipnc

Edited August 20, 2015 by tricecold

[sultan]

sorry cant download files at work, had to wait until home,

but as for number 4, you can create sink objects, by holes I meant to remove particles from within the sim, so you give away other particles to keep falling. Its in the file also

 

In the file there is an example file for drifting clumps randomly also, its for particles but will work for grain also same way. you can play with the noise settings to make sharper or softer activation areas etc.

 

Ok. But do check the file.

 

i checked your file.. Thanks tricecold

 

 

1.

why you created DetailAttribute in box called "doppath" = "/obj/AutoDopNetwork/box", how are you using this ?

 

2.

How does SOPSolver functions?

Does the DopImport contains the PopGrains particles ?

 

3.

Inside the SOPSolver, you grouping the PopGrain particles which are inside the BoundingBox of SinkGeometry and deleting/removing those particles. Now as they get removed, its place is vacant, so the other particles falls down due to gravity to that vacant space and later gets deleted. Is this the behavior/logic of your network ?

 

4.

Initially, all the particles fall down and then come to rest, thus loose the shape of the box from which it was created from. Whereas, we want the initial shape to be same. How to achieve that ?

Edited August 21, 2015 by sultan

[tricecold]

1)doppath is created inside AutoDop, from shelf by default, not my creation

2)sopsolver kinda overwrites information manually inside autodop. dop_geometry brings in the sim geo, then you do whatever u want and updates the result to the next frame

3)by removing points from the simulation, you open up more space for particles to fill in, yes thats the idea

4)You can save sim files under cache option , where you save sim files to resume, and choose save checkpoints with trail lenght of 1, , simulate until sand comes to a rest 10 frames 5 frames whatever, then load that sim file into DOP nets initial state.

Edited August 21, 2015 by tricecold

[sultan]

Keeping the initial shape is important as then we can use any object for the shape.

So we can model shell surface of sand like on the beach (sand shape like dunes) and then create POPGrains & do the effect of clumps of sand going inside whereas the other is still jus like in "Dry QuickSand".

Edited August 21, 2015 by sultan

[sultan]

1. i meant after the cookie, you created an attribute using the "AttributeCreate" SOP. What is the need for this attribute ?

2. Ok

3. Ok

4. but i need the shape. Simulating to get the rest shape changes the shape required. Any other way to get the initial shape maintained?

As an example or reference, its like "Dry Quicksand" effect.

[sultan]

Your file worked correct, just that it did not retained the shape it was created from, like the box.

Its dry quicksand effect of sand going inside, without standing on it

Sand going inside at random clumps of area on the surface.

 

So what you suggest

Edited August 21, 2015 by sultan

[sultan]

Initial state vanishes after frame 1 ??

[sultan]

1)doppath is created inside AutoDop, from shelf by default, not my creation

2)sopsolver kinda overwrites information manually inside autodop. dop_geometry brings in the sim geo, then you do whatever u want and updates the result to the next frame

3)by removing points from the simulation, you open up more space for particles to fill in, yes thats the idea

4)You can save sim files under cache option , where you save sim files to resume, and choose save checkpoints with trail lenght of 1, , simulate until sand comes to a rest 10 frames 5 frames whatever, then load that sim file into DOP nets initial state.

 

i saved InitialState using FileDOP and supplied the .sim file into DOP's initial state... But after frame1 the particles  vanishes ??

 

Also, i didnt get your way of saving initital state ?

 

4)You can save sim files under cache option , where you save sim files to resume, and choose save checkpoints with trail lenght of 1, , simulate until sand comes to a rest 10 frames 5 frames whatever, then load that sim file into DOP nets initial state.

 

Where is the cache option and trail length ?

Edited August 22, 2015 by sultan

[tricecold]

attribute create is created by default when you assign a static object to a simulation from the shelf, again I didnt make it.

as for initial state options look at the attached image

 

 

[sultan]

attribute create is created by default when you assign a static object to a simulation from the shelf, again I didnt make it.

as for initial state options look at the attached image

 

Got it.

Now initial state also working correctly. Thanks tricecold