[x3d-public] Extrusions, take 3

John Carlson yottzumm at gmail.com
Wed Jan 27 04:04:42 PST 2016 

I guess what I am trying to say is, even though you can specify a cylinder with a central point, a height and a radius, it’s much more convenient to do it with 2 points and a radius.  If you need a height, you can subtract and take the normal, whereas getting the second point with a height is very problematic except in one direction.  Does anyone disagree?


> On Jan 27, 2016, at 12:53 AM, John Carlson <yottzumm at gmail.com> wrote:
> 
> So if one has to take a line segment and transform it to another line segment in space, what’s the typical algorithm to do that?  I probably used to know this.  I was trying to work it out again a while back.
> Do the new declarative nodes in V4+ support this?  Or the old nodes in V3?  Or does one need a script?  Is there a node with a linear transform defined by 12 numbers (4 SFVec3f)?  Could there be?
> 2 PositionInterpolators?  Then how does that become a transform?
> 
> Thanks,
> 
> John
> 
>> On Jan 27, 2016, at 12:33 AM, John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com>> wrote:
>> 
>> Better yet, define a script which takes two endpoints on a geometry, then transform the two endpoints (and thus the geometry) with the script.  Hm.  I might be able to do this myself.  Hmm.
>> Sound more possible with Cylinders defined by X3D now.  Took me long enough.
>> 
>> John
>>> On Jan 27, 2016, at 12:26 AM, John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com>> wrote:
>>> 
>>> I just realized the code was online here:
>>> 
>>> https://github.com/coderextreme/X3DJSONLD/blob/master/force.x3dhttps://github.com/coderextreme/X3DJSONLD/blob/master/force.x3d <https://github.com/coderextreme/X3DJSONLD/blob/master/force.x3dhttps://github.com/coderextreme/X3DJSONLD/blob/master/force.x3d>
>>> 
>>> (click raw)
>>> 
>>> Here’s the challenge.  Define an IFS by two endpoints, and then move those endpoints around with minimal scripting (Declarative 3D).
>>> 
>>> John
>>>> On Jan 26, 2016, at 11:45 PM, John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com>> wrote:
>>>> 
>>>> I am not "modeling" I am doing declarative 3d as much as possible and scripting the rest.  Thus I am creating protos for edges and nodes of a 3D graph.  I currently use ROUTES to link the edges  (cylinders/extrusions) to the nodes (spheres).   I am using position interpolators to animate the nodes, and routes to update the spline of the edges.  I do not understand how to use Cylinders as defined by X3D in this way so I use extrusions.  If you can suggest a way to implement a 3D graph without extrusions, I would be welcome to hear it.  I can provide source code if you like.  I have posted force.x3d here, or you can look at force.json in https://github.com/coderextreme/X3DJSONLD/ <https://github.com/coderextreme/X3DJSONLD/>
>>>> On Jan 26, 2016 11:27 PM, "Leonard Daly" <Leonard.Daly at realism.com <mailto:Leonard.Daly at realism.com>> wrote:
>>>> On 1/26/2016 5:21 PM, John Carlson wrote:
>>>>> All I would really like to see is an easy way to define Cylinder with 2 endpoints and a radius.  If that is provided, I have no problem with deprecating Extrusion from the standard.
>>>>> I do not think defining a Cylinder in this way would be onerous to a run-time, but I could be wrong.  If someone could provide an example of a Cylinder like this, it would be great!
>>>> 
>>>> John,
>>>> 
>>>> You using Extrusion to define a cylinder with known endpoints, as opposed to using a Transform {Shape {Cylinder}} to do that based on the center point and height then rotated & translated into place.
>>>> 
>>>> I gather you are doing your modeling by hand in a text or xml editor (like X3D-Edit). There is almost no commercial modeling-by-hand. I do not know of any professional or amateur modeler creating commercial quality models working that way. I think you will find a tool like Blender solves a lot of your modeling issues.
>>>> 
>>>> 
>>>> Leonard Daly
>>>> 
>>>> 
>>>> 
>>>> 
>>>>> John
>>>>>> On Jan 26, 2016, at 8:13 PM, John Carlson <yottzumm at gmail.com> <mailto:yottzumm at gmail.com> wrote:
>>>>>> 
>>>>>> Uh, I asked for an IndexedFaceSet.  Thanks, though.
>>>>>> 
>>>>>> John
>>>>>>> On Jan 26, 2016, at 8:11 PM, doug sanden <highaspirations at hotmail.com> <mailto:highaspirations at hotmail.com> wrote:
>>>>>>> 
>>>>>>> 
>>>>>>> http://dug9.users.sourceforge.net/web3d/tests/41.x3d <http://dug9.users.sourceforge.net/web3d/tests/41.x3d>
>>>>>>> 
>>>>>>> snake animation animating extrusion spine
>>>>>>> 
>>>>>>> From: x3d-public [x3d-public-bounces at web3d.org <mailto:x3d-public-bounces at web3d.org>] on behalf of John Carlson [yottzumm at gmail.com <mailto:yottzumm at gmail.com>]
>>>>>>> Sent: January 26, 2016 6:04 PM
>>>>>>> To: Leonard Daly
>>>>>>> Cc: x3d-public at web3d.org <mailto:x3d-public at web3d.org>
>>>>>>> Subject: Re: [x3d-public] Extrusions, take 3
>>>>>>> 
>>>>>>> Maybe just show an example of an IndexedFaceSet which is an extrusion of a circle with 3 spline points, with the “bend” animated from 90 to 180 degrees.
>>>>>>> 
>>>>>>> It’s okay to use Blender or Maya, I’d just like to see what the results look like.
>>>>>>> 
>>>>>>> John
>>>>>>> On Jan 26, 2016, at 8:01 PM, John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com><mailto:yottzumm at gmail.com> <mailto:yottzumm at gmail.com>> wrote:
>>>>>>> 
>>>>>>> So how do you propose to animate IndexedFaceSets in a declarative or VRMLscript or JavaScript manner if they are Extrusions?  Can we see an example?  If the developer has to do it, can we help them?
>>>>>>> 
>>>>>>> John
>>>>>>> On Jan 26, 2016, at 6:58 PM, Leonard Daly <Leonard.Daly at realism.com <mailto:Leonard.Daly at realism.com><mailto:Leonard.Daly at realism.com> <mailto:Leonard.Daly at realism.com>> wrote:
>>>>>>> 
>>>>>>> On 1/26/2016 3:21 PM, John Carlson wrote:
>>>>>>> Leonard, I think you forget that Extrusion splines etc. can be animated.  If Maya can export an Extrusion animation to X3D V4.0 and your new elements can handle animation of it, I think we are fine.
>>>>>>> 
>>>>>>> In Maya and Blender, extrusions are converted to IndexedFaceSets. These can be animated through the usual mechanisms in those applications. The results are typically stored in a FBX file. Unfortunately, the FBX format is not open and not too conducive to importing in a browser. Autodesk provides a C++ and Python API for accessing the file.
>>>>>>> 
>>>>>>> Extrusions are just a convenience node for creating a constrained IndexedFaceSet. I am working on exactly how X3D fits in the process chain from modeling tools to display. The goal is that X3D is an declarative archivable format that has a browser-based run time. The goal is to not reduce the display capability of X3D in that chain; however, not all of the functionality of X3D V3.3 is necessary to remain in the node definitions to make that happen.
>>>>>>> 
>>>>>>> Animation of the spline and cross-sections of an extrusion is much easier for the developer, but puts a much greater load on the run-time as it needs to re-triangulate the result on each animation.
>>>>>>> 
>>>>>>> 
>>>>>>> Leonard Daly
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> John
>>>>>>> On Jan 26, 2016, at 1:47 PM, Leonard Daly <<mailto:Leonard.Daly at realism.com> <mailto:Leonard.Daly at realism.com>Leonard.Daly at realism.com <mailto:Leonard.Daly at realism.com><mailto:Leonard.Daly at realism.com> <mailto:Leonard.Daly at realism.com>> wrote:
>>>>>>> 
>>>>>>> I would like to ask the question very differently. My question is not to ignore the importance of getting the definition correct for X3D <= V3.3.
>>>>>>> 
>>>>>>> 
>>>>>>> Most (>95%) 3D modeling is done with a tool. In non-CAD environment, the tools is almost certainly Maya or Blender. Both of those tools have extrusions built in to their interface. I imagine CAD tools are similar. With so many tools providing graphical extrusion editors, and some of the tools being open-source (at least Blender);
>>>>>>> 
>>>>>>> Do we need an extrusion node in V4 to support content developed for V4+?
>>>>>>> 
>>>>>>> 
>>>>>>> Leonard Daly
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> On 1/26/2016 7:15 AM, Alekseyev, Vsevolod (NIH/NIAID) [E] wrote:
>>>>>>> Hi X3D community,
>>>>>>> 
>>>>>>> I've tried and failed twice to explain the problems with the definition of the Extrusion node. So here's a tl;dr version:
>>>>>>> 
>>>>>>> Dear authors of the X3D standard, please take a careful look at the standard and answer me:
>>>>>>> 
>>>>>>> 1) When the spine goes (0,0,0)-(0,-1,0), what is the CSP?
>>>>>>> Note: all answers but one will render one of the reference models in the Savage archive invalid.
>>>>>>> 
>>>>>>> 2) When the spine goes (0,0,0)-(0,1,0)-(0,0,0), what is the CSP?
>>>>>>> 
>>>>>>> 3) When the spine goes (0,0,0)-(1,1,0)-(1,1,0)-(1,1,0)-(2,0,0), what is the CSP for the three middle points?
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
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>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> --
>>>>>>> Leonard Daly
>>>>>>> 3D Systems & Cloud Consultant
>>>>>>> X3D Co-Chair on Sabbatical
>>>>>>> LA ACM SIGGRAPH Chair
>>>>>>> President, Daly Realism - Creating the Future
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>>>>>>> x3d-public mailing list
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>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
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>>>>>>> 
>>>>>>> 
>>>>>>> --
>>>>>>> Leonard Daly
>>>>>>> 3D Systems & Cloud Consultant
>>>>>>> X3D Co-Chair on Sabbatical
>>>>>>> LA ACM SIGGRAPH Chair
>>>>>>> President, Daly Realism - Creating the Future
>>>>>>> _______________________________________________
>>>>>>> x3d-public mailing list
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>>>>>>> 
>>>>>>> 
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>>>> 
>>>> 
>>>> -- 
>>>> Leonard Daly
>>>> 3D Systems & Cloud Consultant
>>>> X3D Co-Chair on Sabbatical
>>>> LA ACM SIGGRAPH Chair
>>>> President, Daly Realism - Creating the Future
>>> 
>> 
> 

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