[x3d-public] Gravity Sensor?

Tue Apr 28 09:55:23 PDT 2015

Dave,

Do you have a particular open-source physics engine that you like? Have 
you done any work in trying to integrate one into an X3D scene? We would 
really like your input and expertise here.

Thanks,

Leonard Daly

> This has been a bother for me since I got into x3d in 2003.
>
> Follow me! @thatvrguy
>
> On 4/24/2015 2:57 PM, Christoph Valentin wrote:
>> Hi Dave,
>>   I believe, X3DOM has done that and I believe a lot of open and/or 
>> closed source game engines have done that. No doubt.
>>   The point is, to have it in an ISO standard on a high layer of 
>> scene description (i.e. X3D/VRML).
>>   All the best
>>
>> Gesendet: Freitag, 24. April 2015 um 19:18 Uhr
>> Von: "Dave A" <dave at realmofconcepts.com>
>> An: "Christoph Valentin" <christoph.valentin at gmx.at>, 
>> x3d-public at 3dnpvei.com, "Roy Walmsley" <roy.walmsley at ntlworld.com>
>> Cc: x3d-public at web3d.org
>> Betreff: Re: [x3d-public] Gravity Sensor?
>> I think what you are asking for is a Physics Engine. Has one been
>> integrated yet? It really needs it.
>> I think x3dom glued one in somehow.
>> Dave Arendash
>>
>> On 4/24/2015 7:16 AM, Christoph Valentin wrote:
>>> Thanks Lauren and Roy,
>>>
>>> My question was from a theoretical perspective (maybe I will do some 
>>> trials with GeoSpatial component soon).
>>>
>>> Thinking about railway cars, that contain scenery and avatar can 
>>> enter. --> need superposition of gravity and inertial forces (from 
>>> the acceleration of the railway car).
>>>
>>> KR
>>>
>>>
>>>
>>> Gesendet: Freitag, 24. April 2015 um 14:12 Uhr
>>> Von: GLG <x3d-public at 3dnpvei.com>
>>> An: x3d-public at web3d.org
>>> Betreff: Re: [x3d-public] Gravity Sensor?
>>> Yes there's ParticleSystems (thanks Roy), maybe the
>>> X3DParticlePhysicsModelNode in particular is what you're looking 
>>> for, or the
>>> X3DParticlePhysicsModelNode. Cheers, Lauren
>>>
>>>
>>> 40.4.4 ForcePhysicsModel
>>>
>>> GravityPhysicsModel : X3DParticlePhysicsModelNode {
>>> SFBool [in,out] enabled TRUE
>>> SFVec3f [in,out] force 0 -9.8 0 (∞,∞)
>>> SFNode [in,out] metadata NULL [X3DMetadataObject]
>>> }
>>> The ForcePhysicsModel node specifies a physics model that applies a 
>>> constant
>>> force value to the particles. Force may act in any given direction 
>>> vector at
>>> any strength.
>>>
>>> The force field is used to indicate the strength and direction of 
>>> the force
>>> (e.g., gravity) that should be applied. Force is specified in metres 
>>> per
>>> seconds-squared (m/s2). If the particles are defined to have zero 
>>> mass by
>>> the emitter, the ForcePhysicsModel node has no effect.
>>>
>>>
>>> 40.4.1 BoundedPhysicsModel
>>>
>>> BoundedPhysicsModel : X3DParticlePhysicsModelNode {
>>> SFBool [in,out] enabled TRUE
>>> SFNode [in,out] geometry NULL [X3DGeometryNode]
>>> SFNode [in,out] metadata NULL [X3DMetadataObject]
>>> }
>>> The BoundedPhysicsModel node specifies a physics model that applies a
>>> user-defined set of geometrical bounds to the particles.
>>>
>>> The geometry field specifies a piece of geometry that models the 
>>> bounds that
>>> constrain the location of the particles. When a particle touches the 
>>> surface
>>> of the bounds, it is reflected. The particles may be restricted to 
>>> an inside
>>> location or an outside location. All geometry defined by the bounds are
>>> considered to be non-solid, regardless of the setting of the solid 
>>> field. It
>>> does not matter whether the particle impacts the front or back side 
>>> of the
>>> geometry. Particles are reflected at the same angle to the normal of 
>>> the
>>> surface to which they impact, continuing in the same direction. The
>>> calculation of the correct normal is determined by the rules of the 
>>> geometry
>>> that forms the bounds.
>>>
>>> EXAMPLE A particle can be made to bounce off an elevation grid 
>>> representing
>>> terrain.
>>>
>>>
>>> http://www.web3d.org/documents/specifications/19775-1/V3.2/Part01/components 
>>>
>>> /particle_systems.html
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: x3d-public [mailto:x3d-public-bounces at web3d.org] On Behalf Of Roy
>>> Walmsley
>>> Sent: Friday, April 24, 2015 5:31 AM
>>> To: 'Christoph Valentin'; 'X3D Graphics public mailing list'
>>> Subject: Re: [x3d-public] Gravity Sensor?
>>>
>>> Christoph,
>>>
>>> In X3D the only place where forces, including gravity, can be 
>>> included is in
>>> the Particle systems component.
>>>
>>> There isn't anything like a "gravity sensor". You have to take care 
>>> of it
>>> yourself. This could be done using external code and interacting 
>>> through the
>>> SAI. Alternatively, you could use a Script node to keep everything 
>>> internal
>>> to the scene.
>>>
>>> >From your reasoning point d) I am assuming you are working with the
>>> GeoSpatial component. What sort of things do you want to apply 
>>> gravity to?
>>>
>>> Roy
>>>
>>> -----Original Message-----
>>> From: x3d-public [mailto:x3d-public-bounces at web3d.org] On Behalf Of
>>> Christoph Valentin
>>> Sent: 24 April 2015 10:04
>>> To: X3D Graphics public mailing list
>>> Subject: [x3d-public] Gravity Sensor?
>>>
>>> A few questions to the community.
>>>
>>> Is there something like a "gravity sensor" in X3D/VRML?
>>>
>>> Reasoning:
>>>
>>> a) The Web3D Browser cares for gravity and collision detection, when
>>> controlling the movement of the avatar.
>>> b) However, when controlling the dynamics of an arbitrary object, I 
>>> have to
>>> care for gravity and collision myself
>>> c) In classical scenes, the gravity is 9.81 m.s^-2 in -y direction, no
>>> problem
>>> d) But how to calculate gravity in an X3D-Earth scene? Don't we need 
>>> a kind
>>> of "gravity sensor" here?
>>>
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>> -- 
>> Follow me! @thatvrguy
>>
>
>
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-- 
*Leonard Daly*
X3D Co-Chair
Cloud Consultant
President, Daly Realism - /Creating the Future/
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