bullet physics for DS 1, 2, 3, 4 PC/Win ... teaser

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  • mCasualmCasual Posts: 4,607
    edited November 2013

    new version of the client and new version of the server ( engine ) was posted

    notable change, you have access to the type 2 hinge ( steer and roll ) parameters

    the limit angles, the linear limits the suspension springs

    manual will be updated tomorrow concerning those changes

    https://sites.google.com/site/mcasualsdazscripts3/mcjbulletservice01

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  • patience55patience55 Posts: 7,006
    edited December 1969

    Oh that looks like fun {and much safer for Amy lol ...} :-)

  • mCasualmCasual Posts: 4,607
    edited December 1969

    Oh that looks like fun {and much safer for Amy lol ...} :-)

    off-screen the road flattens and she can get back to the safety pf her star-actor accomodations

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  • mCasualmCasual Posts: 4,607
    edited November 2013

    how the Dakota prop was rigged for the test simulation

    the ground cube was a 10 m. x 10 m cube turned into a static body

    example of a type 2 hinge rig

    the blue cube named "car body" is a dynamic body with a mass of 800
    setting the mass is done in the Physics/Body" section of the parameters tab
    make sure the collision shape selected for those to be "btBoxShape"
    collision shape selection is done in the Physics/Body" section of the parameters tab
    the Dakota's body is parented to it
    the two Type 2 hinges may be parented to it ( else they are left behind during the simulation )

    the large red cylinders are dynamic bodies with a mass of 50
    setting the mass is done in the Physics/Body" section of the parameters tab
    they are named "front wheel" and "rear wheel"
    make sure the collision shape selected for those to be "btCylinderShape"
    collision shape selection is done in the Physics/Body" section of the parameters tab
    the Dakota's wheels are parented to them

    the green cylinders are type 2 ( steer and roll ) hinges

    the green cylinder is also the steer axis ( axis 1 )
    the smaller red cylinder is the roll axis ( axis 2 )
    the roll axis must be a child node of the steer axis
    parenting can be performed in Daz Studio's Scene Panel ( or using my mcjParent script )
    the label of the roll axis must contain the word "roll"
    re-labeling can be performed in Daz Studio's Scene Panel

    in the parameters tab of the hinge nodes :

    the front hinge links "car body" to "front wheel"
    body__A = "car body"
    body__B = "front wheel"

    the rear hinge links "car body" to "rear wheel"
    body__A = "car body"
    body__B = "rearwheel"

    the hinge spring parameters ( which may not be ideal ) were

    spring: On
    stiffness : 1.0
    damping: 0.01
    angular limits: -1 degree to 1 degree
    linear limits: -10 cm to 10 cm

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  • mCasualmCasual Posts: 4,607
    edited December 1969

    note that this poser/daz compatible low-poly Dakota prop

    with functional wheels, openable doors , and leather seats

    can be yours for free right over here

    https://sites.google.com/site/mcasualsdazscripts2/mcjdakota

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  • mCasualmCasual Posts: 4,607
    edited November 2013

    understanding the linear limits of the hinges

    apparently the springs on the hinges are always on

    this will be fixed in the next version

    so for now you could leave the limits at -0.001 and 0.001 to get the equivalent of a disabled spring


    in the figure 1 animation

    linear lower limit 0
    linear upper limit: 1
    spring off

    presently "spring off" means the physics' engine default settings are used

    probably stiffness is 0.0 and damping is 1.0

    to give you an idea of the sizes, the diameter of the yellow cylinder is 1 meter

    we get a spring compression of 1 meter

    in figure 2 you can see a plot of the position of the cyan cube ( the first body attached to the hinge )

    using a linear-lower-limit below 0.0 gives us a behavior that is hard ( for me ) to figure

    but using linear lower lower limit = 0 and linear upper limit = positive works well

    my conclusion is that the limits should be called

    minimum spring compression and maximum spring compression

    indeed if you look at the case where linear lower limit = 0.2

    the simulator forced a compression of the spring at frame 1

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  • mCasualmCasual Posts: 4,607
    edited December 1969

    constraint-hinge parameters take some trial and error work

    often it seems the constraints are fighting one against the other

    one way to solve this seems to make the body of the car much heavier than the wheels

    in the example below wheel mass = 4 car body mass = 400

    hinge parameters

    linear lower limit 0

    linear upper limit 0.1 ( 10 cm )

    spring On

    stiffness 50

    damping 0.001

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  • mCasualmCasual Posts: 4,607
    edited December 1969

    in a previous test increasing the ground cube thickness helped

    in this case increasing the wheel widths helped

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  • mCasualmCasual Posts: 4,607
    edited November 2013

    maybe locking wheels and bizarre speed profiles are due to friction properties of the wheels
    so next i'll look into adding access to that

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  • mCasualmCasual Posts: 4,607
    edited November 2013

    see see ?

    a motor

    so that's nice, we'll have motors

    though i have to fix the hinge which is has an offset on it joint location

    ----
    in case anyone is following this and trying out type A hinges
    the physics engine works better if your physical bodies have their Origin at the center of mass of the body
    to change the location of the Origin, i use the MoveOrigin script by DeltaX15
    ( which is quite an essential tool if you create complex props in Daz Studio )
    Primary Download Link http://www.4shared.com/dir/722776/10801f63/DS_Scripts.html
    Alernative Download Link 1 http://www.savefile.com/files/112075
    Alternative Download Link 2 http://www.badongo.com/file/1468225
    ----
    figure 3 shows the way the "angular motor" in Bullet Physics behave
    i often read that bullet physics is meant for games and not for precise realistic simulations
    and i think the motors are an example of that
    i read elsewhere that those motors are also weak !
    it's odd ( and possibly not true ), but some people were trying to
    build machines with motors and the motors were too weak to lift heavy objects

    using the parameters

    enableAngularMotor, (, bool, enableMotor,. btScalar, targetVelocity,. btScalar, maxMotorImpulse. )

    hingeConstraint->enableAngularMotor( true, 3.1416*3, 10 );

    we obtained an angular speed of 3/2 turns per second

    3 pi is 1.5 times 360 degrees expressed in radians ... so we understand targetVelocity

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  • mCasualmCasual Posts: 4,607
    edited December 1969

    a fancy fast car !

    ( angular motor for type 2 ( steer and roll ) hinges

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    Your such a code genius. I don't understand a bit of it but I like the fun animations

  • patience55patience55 Posts: 7,006
    edited December 1969

    Oh! The makings for a car right out of Bedrock :-)

  • mCasualmCasual Posts: 4,607
    edited November 2013

    fluke object ( called it heavenly star ) while generating icosahedrons from dodecahedrons

    fig 2 is the intended result

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    PURTY!

  • sjfryer_a638239a69sjfryer_a638239a69 Posts: 19
    edited December 1969

    The three princes would be proud of you!

  • mCasualmCasual Posts: 4,607
    edited December 1969

    yes yes i will get back to the physics simulator :)

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  • patience55patience55 Posts: 7,006
    edited December 1969

    Casual said:
    fluke object ( called it heavenly star ) while generating icosahedrons from dodecahedrons

    fig 2 is the intended result

    Whoa! That's kool! Aren't flukes fun ;-)

  • mCasualmCasual Posts: 4,607
    edited November 2013

    tomorrow i'll most likely post version 02 of the physics simulation kit
    with always-on or always off motors

    eventually the motors will be animatable

    and down the road i didnt say it but there may be a "real time" interactive mode

    ---

    of course it all depends if i dont get caught in making cars for Amy

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    Love the VW! Love that car!

  • mCasualmCasual Posts: 4,607
    edited November 2013

    RAMWolff said:
    Love the VW! Love that car!

    i'll probably put it on mys site for free ... before xmas hopefully :)

    it now has an interior lining and open'able doors and the windshields are almost there

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    WOW... that's really awesome!

  • atticanneatticanne Posts: 3,009
    edited December 1969

    Where's old Santa Claus? I want to sit on his lap and tell him to put one of these in my driveway Christmas morning.

  • edited December 1969

    Cool car!!!!

    (... I hope it will have moveable pedals ;) )

  • mCasualmCasual Posts: 4,607
    edited December 2013

    tightened ( and will have to un-tighten the fit of the doors

    finalized the flat rounded cornered windshields

    improved the VW crest

    added door hinges

    improved the V/nose thing :)

    ----
    it will be a multi-part prop so ... likely all the hinged things will be animatable including simple pedals

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    Your so pretty and witty and VEeeWyullllle

  • atticanneatticanne Posts: 3,009
    edited December 1969

    Part of me wants to say Hurry Hurry; the other part says Take your time and get it right. Thank goodness you're the one doing this so it's your call.

  • mCasualmCasual Posts: 4,607
    edited December 2013

    the rear of the cab now correctly attached to the uh pickup bed

    the side windows

    the quick n dirty hubcaps

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  • RAMWolffRAMWolff Posts: 10,211
    edited December 1969

    Looks fabulous!

  • mCasualmCasual Posts: 4,607
    edited December 2013

    now addressing the issue of inclined door hinge axis oh my

    not to mention the fact that nobody knows what's the plural of axis

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