Talk:Sculpted Prims: Technical Explanation

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Rename?

Several commenters on the Sculpted Prims:Talk page have suggested renaming this page to facilitate the effort of consolidating and merging all the good stuff from various sculptie-related pages. I think this page could very well stand side by side with the new Sculpted Prims: FAQ page and perhaps be renamed to Sculpted Prims: Under the Hood?
⇒ Rationale: While the FAQ naturally focuses on aggregating all sorts of question, this page could provide the "anchor", i.e. a detailed technical explanation as well as definitions of technical terms specific to the area of 3D modeling / computer graphics. I think that the beginnings of a Glossary over at this page could be added to the bottom here, where it could be revised and expanded. Thoughts?
Yuu Nakamichi 16:31, 8 May 2007 (PDT)


Other Talk

Eddy - SWEEEET. SWEEET SWEEET SWEET. thank you. --Qarl Linden 10:15, 30 April 2007 (PDT)


PS: regarding that apple texture - by my estimate that texture has been jpeg encoded at LEAST 4 times - which probably explains why your wireframe is so jaggy. let me get you an uncompressed version later today. --Qarl Linden 10:15, 30 April 2007 (PDT)

I think I died and went to heaven. Thanks for the explanation about the uvspace and mesh, makes it easier to approximate offline. Seems like all my 3d skills will be finally used in SL, once this feature enters the grid :D --Hypatia Callisto 16:08, 30 April 2007 (PDT)


Mmmmm... where can i download this software ? :D Kerunix Flan 08:19, 2 May 2007 (PDT)

User:Eddy_Stryker/XNA_Sculptpreview

This is a great article which (almost) totally defines how sculpties will work. Only one question: I don't understand how the pole points work. Are all the points in the top and bottom rows collapsed into one point to which all the grid lines from the row above converge? If so how is this point's position determined? Or are an 'extra' 2 points added, presumably with mesh lines from every point in the top or bottom row (as appropriate). In this case, where are the extra points positioned?

In my program I take the average position of the top and bottom rows and use that as the position for each pole, while keeping the UV coordinates the same. Collapsing the rows seems to have the same results as the SL preview so I'm guessing this is the correct behavior. Eddy Stryker 05:54, 5 May 2007 (PDT)


Could I get a clarification on the vertices vs. faces? It sounds like the sculpt map encodes vertices, but a UV map basically blocks off faces right? So let's say I have a 32x32 checkerboard pattern, and a sculp map that collapses to the 32x32 mesh as explained on this page. Ignoring things like compression artifacts and all that, are the squares of my checkerboard going to map onto the vertices of the sculp map, or is there a shift of some sort to align the texture to the spaces between the vertices? If it's a direct mapping, how are the poles handled?--Watermelon Tokyo 17:04, 24 May 2007 (PDT)

Not the best explanation :(

After reading this page (and all the rest), it remains remarkably *unclear* how the visible textures on sculpted prims work, how to actually create a sculpted prim in a 3D program, or how to export them once you have done that. The page in particular contains endless detail about the theory of using the pixel map as a position map etc., which although interesting is really not useful at all (unless you are foolish enough to attempt to create one by hand in PShop or something)

I also remember LL saying the sculpted prim would not be released into the wild before exporters from popular 3D programs had been created by LL, yet here they are, and there are no exporters in sight and little to no information.


What's really galling is that most of the references to 3D creation programs in these articles seem to also assume:

- You will be using Maya exclusively.

- You will use Windows (Maya is crap on anything else)


All the veterans of Maya on Windows now have a huge leg up in creating SL objects I suppose. Just for giggles though, is it possible that any information exists on how to actually create these suckers in something less proprietary like say ... blender? I am a smart, capable, experienced SL creator who uses a Mac and in RL I am a sculptor. I guess the choice to use a Mac leaves me out of everything now? I certainly am not going to learn Windows and Maya just to continue creating objects for SL.

Sigh. Why did I think it was going to be different this time?

What ever happened to "creating one's own world"?? Now the creation process is so difficult we will have to buy everything from off-world commercial prim makers that have no interest in playing the game and are only in it for the money.

Greeeeaatttt! :p


First off, all the pages here and most of the tutorials linked to them are being written by other Residents and are majorly works in progress, many in need of fleshing out and a lot of copyediting. Its barely been a month since sculpties were announced; give us some time for the documentation to mature.
If you had found Sculpted Prims: 3d Software Guide, you might have noticed that sculpt prim creation methoods do exist for Blender, Wings 3d and several other programs, all of them developed by residents. LL didn't say anything about not releasing sculpt prims before they had developed other export methoods. They did promise support for other programs eventualy, we just beat them to it.
This particular page is supposed to be highly technical: it's aimed at a: people working on creating sculpt prim tools/methoods for their prefered software and/or standalone utilities and b: yes, there are people crazy enough to be editing sculpties in Photoshop. This page really does need to be renamed to reflect that. Elle Pollack 22:12, 24 May 2007 (PDT)
Upto now the biggest issue with this page is that it is inaccurate. As a result most created tools and previewers will make wrong assumptions. I never edited it because I assumed some things would get patched before things went to the live grid. As this hasn't happened I'll update the page to more closely reflect what the viewer does. I'm also looking into writing a patch that fixes some annoying side effects of the current implementation. --Blakar Ogre 01:08, 25 May 2007 (PDT)
I'll ask the obvious question then, directed to the Lindens out there. Where the heck is the official information on how this works? What are the specs that the developers implemented this off? Even if it's extremely technical, surely this is the best source of info on what is actually going on? Post those design specs (there ARE design specs right? :O)--Watermelon Tokyo 07:23, 25 May 2007 (PDT)
This article was written largely be a Linden. You can look at the source code of one of the exporters that was base on the information from this article. http://forums.secondlife.com/showpost.php?p=1509324&postcount=22 --Destiny Niles 08:26, 25 May 2007 (PDT)
Qarl Linden hasn't been leaving as many comments on these pages as in the past week or so (someone needs to introduce him to the watchlist) but he checks here when he has time. He did write most of the FAQ (which was initialy the main sculpted prim artice, the later's talk page being the most likely place to get his attention directly) but Eddy Stryker wrote the bulk of this article or at least the first draft. (By the way, Watermellon, have you been introduced to Torley yet? ;) Elle Pollack 05:44, 26 May 2007 (PDT)

Adding Explanation of Each Sculpt Type

I noticed that when changing the shape through LSL scripts you now add a sculpt type (PLANE, CYLINDER, SPHERE, TORUS). I've been able to do some testing and the different types work like this:

  • PLANE
Like a flat piece of paper twisted and folded into a shape. This seems to be the default type shown in the image preview now.
  • CYLINDER
The left and right sides of the sculpted are stiched together but top and bottom sides are left unstiched and positioned as encoded.
  • SPHERE
Sides are stitched together like the Cylinder but the top and bottom sides are pinched together to form points on either end.

From what I can tell it looks like the leftmost pixel on the top and bottom rows determine the location of the "point" or "pole". The rest of the pixels on the top and bottom rows seem to be ignored.

This is also the default prim type used when one uses the Edit UI to change the prim to a Sculpt type.

  • TORUS
All sides are stiched together. Left and Right vertices are stiched to one another and the Top and Bottom vertices are stiched together.

Is there any way we can see about adding more details about the different types of sculpted prims and what their uses are? Perhaps some examples of the same sculpt texture but with the different types applied? Obsidian Stormwind 15:50, 14 July 2007 (PDT)

Revamping Technical Explanation

I'd like to completely redo this page if possible, its a bit stale and doesn't provide as much information as it could. There's still a lot of confusion about sculpties and how they work and what different topologies mean. I plan to make diagrams of the different topologies, LOD levels, etc, to basically explain as much as possible in visual form (and get rid of that MSpaint diagram up top) .. if anyone has any comments please feel free to share them. --DanielFox Abernathy 14:42, 2 October 2007 (PDT)

Keep it simple Sculpties

I think its worth reitterating that sculpted prims are plain old 24 bit .bmp files and as such can be editted w/ any hex editor. To create a template just create a 24 bit .bmp w/ resolution of lets say 128x128,or 64x64 in a graphics editor such as GIMP, and then make the entire square neutral grey (808080). In the 128x128 bmp there will be 128x128 6-digit(in hex) pixels. These can be changed individually or in groups from the initial value of (808080) to anything in the range (000000-ffffff) where the first 2 digits represent the red value of 0-255, second 2 digits green, last 2 blue. By consulting the chart in the Technical Explanation and a few trial and error experiments the outcome of parameter changes will quickly become intuitive. Also remember that the .bmp is also a UV map so that a texture maps directly to the 3d point designated by the pixel value which is in the line and row coresponding to the same 2d location in the texture file as the sculpty .bmp when the texture is stretched or shrunk to match resolution of the sculpted prim. Upon mastering this technique throw away your mouse and smirk anytime someone mentions Maya, 3d Max, Blender, Art of Illusion, POV...etc.

--GeMlUre Dejavu 09:53, 13 December 2007 (PST)