[x3d-public] Gravity Sensor?

Fri Apr 24 14:57:56 PDT 2015

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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