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Carrara, Physics and Tires

TotteTotte Posts: 13,955
edited December 1969 in Carrara Discussion

Hello,

I'm playing with Carrara again and the physics engine creating piles of stuff. Yeah, it's fun!
I've found that most items works very well, from bricks and blocks to oil barrels, but one shape really messes it up, tires.
They tend to try to creep tight and stack inside each other until there are only a few, mega tires, lol. They collide great with other things except items of their own breed.

Any good hints?

Attached a sample of what I'm playing with.

tireandbrick.jpg
1600 x 642 - 146K
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Comments

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Age off armour made this tuto: http://www.youtube.com/watch?v=-XGRj4VjPqk
    It is perhaps not what you seek, but it is interesting.
    In the Scene/Physic tab, try to changes Bullet in Standard…
    The collision distance is important too.

  • DartanbeckDartanbeck Posts: 21,537
    edited December 1969

    Perhaps place a squashed cylinder primitive in the opening, make it invisible and parented to the tire, and see if the results change? Like a circular plane sitting right in the center?

  • TotteTotte Posts: 13,955
    edited December 1969

    Thanks for somr interesting replies!
    I tried to block the hole of the tires with two round planes, but fill it with a cylinder looks like a good idea. Will check that tutorial too, This is fun to play with!

  • TotteTotte Posts: 13,955
    edited December 1969

    OK, here is a little video where 9 tires magically turns into six ;-)

    Watch carefully and don't try this at home, those tires are trained professionals.

    http://youtu.be/TLJH65HFRNQ

  • VarselVarsel Posts: 574
    edited December 1969

    I did a quick test, and I did manage to get it to work.
    -- That is with only 6 tires, and noting else i the scene....

    Under Scene - in the physics tab -

    Simulation Accuracy to a higher value ( I used 1000)
    Collision Distance to a lower value (I used 0 )

  • TotteTotte Posts: 13,955
    edited December 1969

    Varsel said:
    I did a quick test, and I did manage to get it to work.
    -- That is with only 6 tires, and noting else i the scene....

    Under Scene - in the physics tab -

    Simulation Accuracy to a higher value ( I used 1000)
    Collision Distance to a lower value (I used 0 )

    Thanks, I will try that!!

  • de3ande3an Posts: 915
    edited December 1969

    I also tried to duplicate what is shown in your animation, but got realistic looking results. I see none of the erratic jiggling or merging.
    Are you using an older version of Carrara? The physics simulations were not particularly good until the introduction of the Bullet Physics Solver.
    However, using either the Standard or Bullet Physics Solver in the current version of Carrara seems to produce good results even at the default settings.
    If you're getting this jiggly physics animation in the current Carrara release, then something else is wrong.

  • TotteTotte Posts: 13,955
    edited December 1969

    de3an said:
    I also tried to duplicate what is shown in your animation, but got realistic looking results. I see none of the erratic jiggling or merging.
    Are you using an older version of Carrara? The physics simulations were not particularly good until the introduction of the Bullet Physics Solver.
    However, using either the Standard or Bullet Physics Solver in the current version of Carrara seems to produce good results even at the default settings.
    If you're getting this jiggly physics animation in the current Carrara release, then something else is wrong.

    Carrara 8.5 on Mac OS X. Gonna try a little more with different setting....
    I've been dropping bricks and other stuff, no problem, just those tire objects that behave like cuddly snakes.

  • de3ande3an Posts: 915
    edited December 1969

    Totte said:
    de3an said:
    I also tried to duplicate what is shown in your animation, but got realistic looking results. I see none of the erratic jiggling or merging.
    Are you using an older version of Carrara? The physics simulations were not particularly good until the introduction of the Bullet Physics Solver.
    However, using either the Standard or Bullet Physics Solver in the current version of Carrara seems to produce good results even at the default settings.
    If you're getting this jiggly physics animation in the current Carrara release, then something else is wrong.

    Carrara 8.5 on Mac OS X. Gonna try a little more with different setting....
    I've been dropping bricks and other stuff, no problem, just those tire objects that behave like cuddly snakes.


    How were the tire objects created? Perhaps they contain some corrupted geometry.
    Can you open one of them in the Model Room and examine the geometry? Perhaps post a screenshot.

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Hi Totte,
    As I can see, it seems that you begin this sequence with four wheels but, they are four duplicated wheels, which makes eight of them !
    Considering how these duplications were not moved and remain with the same position as the first, it is normal that this phenomenon occurs, the physical engine becomes crazy !
    Or then, it is a Norwegian joke…;-)

  • TotteTotte Posts: 13,955
    edited December 1969

    de3an said:
    Totte said:
    de3an said:
    I also tried to duplicate what is shown in your animation, but got realistic looking results. I see none of the erratic jiggling or merging.
    Are you using an older version of Carrara? The physics simulations were not particularly good until the introduction of the Bullet Physics Solver.
    However, using either the Standard or Bullet Physics Solver in the current version of Carrara seems to produce good results even at the default settings.
    If you're getting this jiggly physics animation in the current Carrara release, then something else is wrong.

    Carrara 8.5 on Mac OS X. Gonna try a little more with different setting....
    I've been dropping bricks and other stuff, no problem, just those tire objects that behave like cuddly snakes.


    How were the tire objects created? Perhaps they contain some corrupted geometry.
    Can you open one of them in the Model Room and examine the geometry? Perhaps post a screenshot.

    I have the Carrara file here in anyone wanna give it a go
    http://4eyes.code66.se/stuff/trytire.zip (380kb)

    / Totte

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Sorry, I am too tired and I can't count any more…
    Here,we have just the first snow of the year now :-)
    I 'll test your project.

  • DUDUDUDU Posts: 1,945
    edited December 2014

    Here is your project with my settings, that works for me : http://mhdproductions.be/Carrarators/trytire2.zip
    You can reduce the collision distance at 50 but no more (Standart engine).

    Post edited by DUDU on
  • de3ande3an Posts: 915
    edited December 1969

    The problem seems to be that your tires have a thickness to the walls. If you remove the inner surface, the tires behave properly. But with the inner surface it seem like the physics engine is having trouble differentiating between them and the surfaces become entangled.
    I've tried to duplicate this effect with other shapes, but oddly, I have not been successful. It only seems to occur with the tire shape.

    Pretty weird.

  • de3ande3an Posts: 915
    edited December 1969

    I've just figured out how to duplicate this issue with a sphere shape

    By creating a sphere and then adding a small thickness, a sphere within a sphere is created.
    If you then bridge the inner and outer spheres by removing a single inner and outer facet and bridge their edges you create a hollow area that is now open to the outside.

    These spheres will tend to cling to each other under a physics simulation.

    spheres.gif
    600 x 450 - 2M
  • TotteTotte Posts: 13,955
    edited December 2014

    Thanks de3an for the help, now I know what tie issue is (now try to find a way around it, I have a plan.

    Post edited by Totte on
  • evilproducerevilproducer Posts: 9,050
    edited December 1969

    Totte said:
    Thanks de3an for the help, now I know what tie issue is (now try to find a way around it, I have a plan.

    Queue A-Team theme music. ;-)

  • DartanbeckDartanbeck Posts: 21,537
    edited December 1969

    Totte said:
    Thanks de3an for the help, now I know what tie issue is (now try to find a way around it, I have a plan.
    All you really need is the edge of the bead of the tire, not the entire inner surface. So consider selecting one of the center polygons on the outside tread of the tire, then Shift/select the next one that continues around the tread, then Loop the selection so that the selection now travels all the way around the outside in the direction of the tread. Now hit the "+" key to grow the selection until it goes a few polygons inside the bead of the tire. Now inverse the selection and delete.
  • evilproducerevilproducer Posts: 9,050
    edited December 1969

    I' testing a bunch of tires I made in the spline modeler using Carrara 7.2's physics engine which is rigid body of course. I made a cross section with thickness all the way through and used the torus preset to make the tire. I made the surface material rubber and left everything else alone. I duplicated the tire many times and in many positions both in height and relative positions to the other tires. I'll upload the video to youtube when I'm done rendering it, but in the simulations I didn't see the issues the OP was getting.

  • DartanbeckDartanbeck Posts: 21,537
    edited December 1969

    evilproducer said:
    I' testing a bunch of tires I made in the spline modeler using Carrara 7.2's physics engine which is rigid body of course. I made a cross section with thickness all the way through and used the torus preset to make the tire. I made the surface material rubber and left everything else alone. I duplicated the tire many times and in many positions both in height and relative positions to the other tires. I'll upload the video to youtube when I'm done rendering it, but in the simulations I didn't see the issues the OP was getting.
    You and that wonderful Spline Modeler! I think you're going to make that tool famous one day! Bravo, my friend!
  • de3ande3an Posts: 915
    edited December 1969

    I just loaded Totte's original scene file into Carrara 7.2 and ran the physics simulation. It worked perfectly.
    I then tried it in Carrara 8.1 and it failed just like it fails in 8.5.
    So it looks like simulation errors were introduced in version 8.something.

    And it's not just Bullet physics. The standard physics solver in 8.5 won't successfully simulate this file either.

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Here some images to illustrate what I wanted to say in my preceding post:

    https://www.youtube.com/watch?v=GPIfkECLoas&feature=youtu.be

  • TotteTotte Posts: 13,955
    edited December 1969

    de3an said:
    I just loaded Totte's original scene file into Carrara 7.2 and ran the physics simulation. It worked perfectly.
    I then tried it in Carrara 8.1 and it failed just like it fails in 8.5.
    So it looks like simulation errors were introduced in version 8.something.

    And it's not just Bullet physics. The standard physics solver in 8.5 won't successfully simulate this file either.

    Thanks, then I know I'm not just mad, lol!

  • DartanbeckDartanbeck Posts: 21,537
    edited December 1969

    Totte said:
    de3an said:
    I just loaded Totte's original scene file into Carrara 7.2 and ran the physics simulation. It worked perfectly.
    I then tried it in Carrara 8.1 and it failed just like it fails in 8.5.
    So it looks like simulation errors were introduced in version 8.something.

    And it's not just Bullet physics. The standard physics solver in 8.5 won't successfully simulate this file either.

    Thanks, then I know I'm not just mad, lol!
    If you mean "mad" as in "Crazy", Totte, I'm not sure that is actually evidence... you're still mad! :ahhh: LOL
    Just kidding, big guy!

  • TotteTotte Posts: 13,955
    edited December 1969

    Dartanbeck said:
    Totte said:
    de3an said:
    I just loaded Totte's original scene file into Carrara 7.2 and ran the physics simulation. It worked perfectly.
    I then tried it in Carrara 8.1 and it failed just like it fails in 8.5.
    So it looks like simulation errors were introduced in version 8.something.

    And it's not just Bullet physics. The standard physics solver in 8.5 won't successfully simulate this file either.

    Thanks, then I know I'm not just mad, lol!

    If you mean "mad" as in "Crazy", Totte, I'm not sure that is actually evidence... you're still mad! :ahhh: LOL
    Just kidding, big guy!

    Lol!

    I had a record when I was young (you know those big 12" things in vinyl). I can't remember the name of the group or the record but I still have the title track in my head.

    "Out here on the edge of madness, two steps from insanity, out here on the edge of madness, that's where I wanna be"

    And I've been living by that ever since I heard it.

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Was there Bullet physic in Carrara 7 ?

  • evilproducerevilproducer Posts: 9,050
    edited December 1969

    DUDU_00001 said:
    Was there Bullet physic in Carrara 7 ?

    No. Just the rigid body physics.

    Still cool though.

    I went and rendered my scene an it looked fine. I'll upload the video to youtube shortly.

    If anybody wants to test this scene with Carrara's Physics engine in anything later than C7.2, feel free. The tires are spline objects, so it will be interesting to see if the behavior differs from vertex objects.
    https://dl.dropboxusercontent.com/u/7370483/tires.car.zip

  • DUDUDUDU Posts: 1,945
    edited December 2014

    EP,
    I have just tested your scene and that works well in C8.
    That confirms what I think, for the rigid bodies, the standard engine is better !

    PS: I try it with bullet, it's a catastroph !

    Post edited by DUDU on
  • evilproducerevilproducer Posts: 9,050
    edited December 1969

    DUDU_00001 said:
    EP,
    I have just tested your scene and that works well in C8.
    That confirms what I think, for the rigid bodies, the standard engine is better !

    PS: I try it with bullet, it's a catastroph !

    Bullet doesn't like spline objects?

    Here's the video I rendered:
    http://youtu.be/A6YuyxvcXYk

  • DUDUDUDU Posts: 1,945
    edited December 1969

    Bullet like only soft bodies !

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