[x3d-public] Projective Texture Mapping PTM node definitions

[Michalis Kamburelis]

I recall we talked that the PTM specification needs to address how the
projected texture affects the existing textures.

You once mentioned that the original PTM proposal contained the text
effectively meaning that "projected texture is like a light source",
but then this text was simplified (maybe too much) for the actual
spec. As an implementor, looking at WD2 of PTM (
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-WD2/Part01/components/ProjectiveTextureMapping.html
), I don't know how exactly the projected color should be used (at
which point of the lighting equation is it applied).

My old notion about it is on
https://github.com/michaliskambi/x3d-tests/wiki/Clarify-%22Projective-texturing%22-component
, see the section """TODO: Address how the projective texturing in X3D
4 spec affects existing textures""". We talked about this issue on the
mailing list and teleconferences :)

Regards,
Michalis

wt., 6 paź 2020 o 06:00 Don Brutzman <brutzman at nps.edu> napisał(a):
>
> Found that the PTM nodes had never been put into X3D XML Schema, DOCTYPE or X3DUOM, etc. etc.  Working to remedy that.
>
> [1] 42  Projective Texture Mapping (PTM) Component
>      https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-WD2/Part01/components/ProjectiveTextureMapping.html
>
> Suggest following changes in nodes below:
>
> a. modify farDistance, nearDistance to have bounds of [0,∞)
>
> b. farDistance default of 10m seems like a good value if used in virtual rooms. nevertheless might consider longer default value for farDistance, perhaps 100 (meters) to reduce potential for future author puzzlement.
>
> Anything else?
>
> =============================
> 42.3.1 X3DTextureProjectorNode
>
> X3DTextureProjectorNode : X3DChildNode {
>    SFString [in,out] description  ""
>    SFVec3f  [in,out] direction    0 0 1  (-∞,∞)
>    SFFloat  [in,out] farDistance  10
>    SFBool   [in,out] global       TRUE
>    SFVec3f  [in,out] location     0 0 0  (-∞,∞)
>    SFNode   [in,out] metadata     NULL   [X3DMetadataObject]
>    SFFloat  [in,out] nearDistance 1
>    SFBool   [in,out] on           TRUE
>    SFNode   [in,out] texture      NULL   [X3DTexture2DNode]
>    SFFloat  [out]    aspectRatio         (0,∞)
> }
> =============================
> 42.4.1 TextureProjectorParallel
>
> TextureProjectorParallel : X3DTextureProjectorNode {
>    SFString [in,out] description  ""
>    SFVec3f  [in,out] direction    0 0 1     (-∞,∞)
>    SFFloat  [in,out] farDistance  10
>    SFVec4f  [in,out] fieldOfView  -1 -1 1 1 (-∞,∞)
>    SFBool   [in,out] global       TRUE
>    SFVec3f  [in,out] location     0 0 0     (-∞,∞)
>    SFNode   [in,out] metadata     NULL      [X3DMetadataObject]
>    SFFloat  [in,out] nearDistance 1
>    SFBool   [in,out] on           TRUE
>    SFNode   [in,out] texture      NULL      [X3DTexture2DNode]
>    SFFloat  [out]    aspectRatio            (0,∞)
> }
> =============================
> 42.4.2 TextureProjectorPerspective
>
> TextureProjectorPerspective : X3DTextureProjectorNode {
>    SFString [in,out] description  ""
>    SFVec3f  [in,out] direction    0 0 1  (-∞,∞)
>    SFFloat  [in,out] farDistance  10
>    SFFloat  [in,out] fieldOfView  π/4 (0,π)
>    SFBool   [in,out] global       TRUE
>    SFVec3f  [in,out] location     0 0 0  (-∞,∞)
>    SFNode   [in,out] metadata     NULL   [X3DMetadataObject]
>    SFFloat  [in,out] nearDistance 1
>    SFBool   [in,out] on           TRUE
>    SFNode   [in,out] texture      NULL   [X3DTexture2DNode]
>    SFVec3f  [in,out] upVector    0 0 1
>    SFFloat  [out]    aspectRatio         (0,∞)
> }
> =============================
>
> all the best, Don
> --
> Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
> Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
> X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman
>
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