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--></style></head><body lang=EN-US link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><ul style='margin-top:0in' type=disc><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>Understood, Joe! </li></ul><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Fine. Are you sure you see how we drew that part of a box? The coordinates of the points and how to make triangles?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>There is a default 0 0 0 for the root scene. You are not really supposed to draw in this space but recommended to have a Group or Transform to hold geometry. If I say Transform defaults, Shape Box defaults then I get a box 1x1x1 centered at 0 0 0 in ancestor space so the thing should be hanging there around the middle of the scene. For other standard shapes, when the user asks for a cone, he will expect standard cone, but a cone that is not carefully specced out but will probably consist of about what 20 to 50 points. If the user wants more detail or less points then it is fairly easy diyofs in basic IFS user code. </p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks, </p><p class=MsoNormal>Joe</p><p class=MsoNormal> </p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:yottzumm@gmail.com">John Carlson</a><br><b>Sent: </b>Saturday, April 22, 2023 6:35 PM<br><b>To: </b><a href="mailto:joedwil@earthlink.net">Joseph D Williams</a><br><b>Cc: </b><a href="mailto:gpugroup@gmail.com">GPU Group</a>; <a href="mailto:x3d-public@web3d.org">X3D Graphics public mailing list</a><br><b>Subject: </b>Re: [x3d-public] Tessellation…convert to IFS?</p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Understood, Joe! My issue is what do we do with sphere coordinates when transforms are multiplied out and deleted? It would seem natural to replace non-coordinate shapes with some kind of shape set, whether indexed or not (X3D JSON to STL code does this). Especially something where triangles must share edges. So yes, in the case of Sphere, Box and other non-coordinate shapes, the user code should change.</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I think the solution may be to retain lowest level transforms in the scene in order to maintain shapes like spheres, cones, cylinders, etc. in user code. Then, do we need to apply the transforms to geometry?</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Joe, it seems like you’re leaning towards changing the shape user code to sets? This is getting more and more like X3D JSON to STL, we just need to support different output formats and additional shapes. Should we translate to glTF instead of STL?</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Doug, this is primarily to produce a standardized human model.</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>John</p></div><div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Sat, Apr 22, 2023 at 7:03 PM Joseph D Williams <<a href="mailto:joedwil@earthlink.net">joedwil@earthlink.net</a>> wrote:</p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Also note there are several ways to represent a shape in x3d. If the name includes Indexed then the user code includes the coordinates for the points and the sets of coordindex numbers that tell the browser how to make the triangles. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Some styles of shapes do not require the user to supply coordIndex, then the points are default auto-indexed into triangles by a standardized formula depending on name and included user code for points. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>So, when you say shape Sphere then the browser encodes that depending on its internal spec sphere. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>You can see the result in a browser that can just show the points or triangles of the shape sphere otherwise it will appear as a solid but the details of the actual coordinates of points and tessellation (indexing) of those points will not appear in the user code because what does the user care about what the browser uses to create your Sphere? . </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>So, for the default shape Box, probably uses two triangles per side. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I think there is x3d Shape user code to present a box in both indexed and auto-indexed form. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Here is classic-style user code with lots of defaults for one side of a box. </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>DEF boxfront Shape {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> appearance Appearance {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> material Material { }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> texture ImageTexture {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> url [ "textures/boxfront.jpg" ]</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> geometry IndexedFaceSet {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> coordIndex [ 0 1 2 3 -1 ]</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> coord Coordinate {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> point [ -1 -1 1, 1 -1 1, 1 1 1, -1 1 1 ]</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> texCoordIndex [ 0 1 2 3 -1 ]</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> texCoord TextureCoordinate {</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> point [ 0 0 1 0 1 1 0 1 ]</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> }</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>}</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Joe</p></div></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in;border-color:currentcolor currentcolor'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b>From: </b><a href="mailto:gpugroup@gmail.com" target="_blank">GPU Group</a><br><b>Sent: </b>Saturday, April 22, 2023 2:33 PM<br><b>To: </b><a href="mailto:yottzumm@gmail.com" target="_blank">John Carlson</a><br><b>Cc: </b><a href="mailto:x3d-public@web3d.org" target="_blank">X3D Graphics public mailing list</a><br><b>Subject: </b>Re: [x3d-public] Tessellation…convert to IFS?</p></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Depends what you're doing. Assuming you're starting with a point cloud, if you're tessellating something almost flat, and with irregular points, then you can use something like Delaunay algorithm to optimize the edges between points to give triangles that are more equi-angular.</p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>If you are on a 3D dimensional surface, but know its close to being convex -- like a sphere or cube -- then you can move the planar math around a spherical center, and crop points in the distance / on the other side of center when triangulating. </p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Or you can remove and add points from a pre-triangulated sphere (I just made this up). Looking orthogonally at an existing triangle on your sphere, add a point from your point cloud, to the appropriate triangle, based on its yaw and pitch, or latitude, longitude, while ignoring its radius/height. When you have all your points added, then start removing the sphere's points. After each step of adding (or removing sphere points at the end), do Delaunay recursive triangle swaps on the local plane. </p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Or ask ChatGPT - it might know.</p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>-Doug</p></div></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>On Sat, Apr 22, 2023 at 3:05 PM John Carlson <<a href="mailto:yottzumm@gmail.com" target="_blank">yottzumm@gmail.com</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid windowtext 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt;border-color:currentcolor currentcolor currentcolor rgb(204,204,204)'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>When one is tessellating a shape, like Box, is it typical to convert to IFS?</p><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Thanks!</p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> </p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>John</p></div></blockquote></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:4.8pt'>_______________________________________________<br>x3d-public mailing list<br><a href="mailto:x3d-public@web3d.org" target="_blank">x3d-public@web3d.org</a><br><a href="http://web3d.org/mailman/listinfo/x3d-public_web3d.org" target="_blank">http://web3d.org/mailman/listinfo/x3d-public_web3d.org</a></p></div></div></blockquote></div></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:4.8pt'> </p><p class=MsoNormal><o:p> </o:p></p></div></body></html>