[x3d-public] Gravity Sensor?

Fri Apr 24 16:01:41 PDT 2015

This has been a bother for me since I got into x3d in 2003.

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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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