[x3d-public] X3D VR
Holger Seelig
holger.seelig at yahoo.de
Sat Jan 7 12:04:42 PST 2017
I think instead of defining a new field to the existing viewpoints, it
should be considered that for that purpose and new viewpoint node could
be appropriate. A node called something like »MatrixViewpoint«. This
node could have two fields matrix and projectionMatrix. The matrix field
would store the transformation matrix with orientation and position
values. The projectionMatrix field would store the projection matrix.
This viewpoint would be an all purpose viewpoint. The main idea is if
one is able to define an »viewMatrix« field as Andreas proposes he is
able to handle a node like MatrixViewpoint with its matrix fields.
Defining a new node has the advantages to left the existing viewpoints
untouched and to handle this behavior in a new node.
Holger
Am 07.01.2017 um 18:07 schrieb Andreas Plesch:
> Hi,
>
> back from the holiday season, here are proposals for new fields for
> Viewpoint.
>
> I do not have an x3dom implementation but the idea is to add two
> Matrix4d fields:
>
> projectionMatrix :
>
> default: NULL
>
> purpose: allow control of the view projection from 3d to 2d by such a
> matrix from sources such HMD drivers. The projection matrix controls fov
>
> The projectionMatrix should be used as is by the browser if not NULL. If
> NULL, a projection matrix shall be contructed from viewpoint fields.
>
>
> viewMatrix:
>
> default: unit matrix
>
> purpose: allow control of the viewer orientation and location by such a
> matrix from sources such as HMD drivers.
>
> The viewMatrix V shall be combined with the matrix M derived from the
> location/ orientation fields by M * V for rendering use.
>
> This means that if V is used in a scene exclusively the location fields
> needs to be reset to 0 0 0 from its default by the scene.
>
> Typical use would be as sinks of routes from (new) ProjectionSensor or
> VRDevice node fields.
>
> A VRDevice delivers both matrixes for each eye. A scene can then set up
> a viewpoint for each eye, and use Layers to show them side by side.
>
> In terms of efficiency, this would seem to require repeated traversals
> of the scene unless both Layers can be recognized to show the same scene
> content.
>
> A more convenient and integrated alternative would be to introduce a
> stereo SFBool field and have left and right variants of the matrix
> fields ( and perhaps also left and right variants of the location,
> orientation, fov, zfar, znear fields).
>
> stereo = false would ignore all left and right fields.
> stereo = true would use the left/right fields and render them side by side.
>
> Since in this case there is a guaranty that views for each eye use the
> same scene content, only one traversal should be needed to render both eyes.
>
> The idea would be switching mono to stereo and back only requires
> toggling the stereo field. Navigation may have a similar switch to and
> from mouse/keyboard modes ?
>
> Implementation in x3dom of viewMatrix and projectionMatrix may be rather
> straightforward. I do not see large obstacles (famous last words ...).
> Implementation in cobweb of viewMatrix and projectionMatrix may be also
> straightforward but I am less sure.
>
> Without layers in x3dom then one could put two scene side by side on the
> web page, use external js to feed the matrix fields, and then also use
> external js to grab the frames from both scene canvases, combine them
> into a single frame on another canvas, and use that finally as a source
> for the HMD display. (This sounds slow).
> In cobweb, it should not be hard to set up a scene with a layer for each
> eye.
>
> Implementation of stereo, left and rightView/ProjectionMatrix in x3dom
> is harder since it needs changes to the rendering code which is a bit
> unstructured. The first approach would be for stereo=true to go through
> the rendering twice with the rendering surfaces appropriately set somehow.
>
> -Andreas
>
> On Dec 21, 2016 6:00 AM, "Roy Walmsley" <roy.walmsley at ntlworld.com
> <mailto:roy.walmsley at ntlworld.com>> wrote:
>
> Hi Andreas,____
>
> __ __
>
> That’s great to see what you have been doing here. Would you like
> to take your node suggestions one step further and propose the
> fields that might be specified for each node?____
>
> __ __
>
> What we could do then is, in the new year, is to host an open
> discussion on WebVR and X3D. Contributions from any other readers
> are welcome, and could lead to a lively discussion on this topic.____
>
> __ __
>
> Thank you for the suggestions,____
>
> __ __
>
> All the best,____
>
> __ __
>
> Roy____
>
> __ __
>
> *From:*x3d-public [mailto:x3d-public-bounces at web3d.org
> <mailto:x3d-public-bounces at web3d.org>] *On Behalf Of *Andreas Plesch
> *Sent:* 21 December 2016 05:51
> *To:* X3D Graphics public mailing list <x3d-public at web3d.org
> <mailto:x3d-public at web3d.org>>
> *Subject:* [x3d-public] X3D VR____
>
> __ __
>
> Hi____
>
> Working with x3dom and WebVR I am exploring what additions to X3D
> would be necessary or useful to effectively use current VR hardware
> such as the Rift, Vive, Gear, or Cardboard.____
>
> The proposed RenderedTexture node is currently used in x3dom with
> special stereo modes to generate left and right views from a single
> viewpoint in a single GL context.____
>
> A Layer for each left and right view could also be used with two
> coordinated but separate viewpoints. This would be Cobweb's pattern.____
>
> Since the HMD and its own runtime know best the internal optical
> characteristics of the display, the preferred interface at least in
> WebVR are view and projection matrixes directly usable by consumers
> for 3d graphics generation, and not position, orientation and fov.
> This leads to a new requirement for X3D to accept these raw matrixes
> as input.____
>
> Since x3dom uses RenderedTexture for VR, I added there additional
> special stereo modes which directly receive these matrixes from the
> HMD to be used for rendering at each frame. This in effect
> accomplishes a first, head and body based, level of navigation. In
> my first tests (on github) it works well and should be robust across
> devices. This approach does require some standard API to the HMD
> such as WebVR.____
>
> Another possibility is to add view and projection matrix fields
> input fields to viewpoints which can be continually updated. One
> could convolve the view matrix with position/orientation fields, or
> optionally completely ignore them.____
>
> One then could use external SAI to keep updating or perhaps
> introduce an environment ProjectionSensor. It would relay these
> matrix events from an HMD runtime to then be routed to the
> viewpoints.____
>
> A second level of navigation is accomplished with handheld
> controllers. Until some standard gestures evolve, it will be
> necessary to expect custom per scene navigation. X3d should have a
> way to sense buttons and axes velocities of such controllers so
> these are then available to manipulate the view in some way.
> InstantReality has a general IOSensor to that effect. On the web the
> GamePad API is a standard which would need to be used.____
>
> Summary: RenderedTexture with stereo modes, matrix fields for
> viewpoints, a ProjectionSensor, and a ControllerSensor would all be
> candidates for x3d VR support.____
>
> Thanks for reading, any thoughts welcome,____
>
> Andreas ____
>
>
>
>
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--
Holger Seelig
Mediengestalter Digital – Digital Media Designer
Scheffelstraße 31a
04277 Leipzig
Germany
Cellular: +49 1577 147 26 11
E-Mail: holger.seelig at create3000.de
Web: http://titania.create3000.de
Future to the fantasy ★ ★
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