A tip for training for Sculpted Prims

Attached are some examples I prepared the other day in MilkShape in response to a discussion on the talk page of the Wiki entry for Sculpted Prims about what a sculpture map for a cube would look like. I created a sphere, then distorted it into a cube (the hard way... by hand).

The first image is the sphere and cube with shading, which also demonstrates how true sharp corners won't be possible with sculpted prims (though they could be approximated by narrowing the polys near the edge, making a small-radius "bevel".

In the second image, which is unshaded, the wireframes are shown, and a solid-color texture is applied to both objects, demonstrating what polys of the spehere become what sides of the cube. That texture is the 3rd image.

The 4th image is the same two objects textured with a sculpt map texture I created one color channel at a time in CorelDraw, demonstrating how colors translate to relative coordinates. That texture is the 5th image.

And to further clarify, the attached images are the above sculpt mapped render split into its component red, green and blue channels, demonstrating perhaps more clearly how they correlate to X, Y and Z coordinates.

(Ignore that stray triangle on the top face of the cube in the red channel, that was a patch face I had to put in manually, since a few verts accidentally got unified during the manual sphere-to-cube conversion process, and apparently its UV coordinates didn't get assigned correctly)

The only 3D modeler i really like is Milkshape3D : Simple and "it just work".

Tiny question : "will it work to create sculpted prims without additional complex export/plugin/manual processing ?"

e.g : i create a banana, i click here and here, i upload, i have a banana in SL.

I'm looking into making a sculpt map export plugin for MilkShape. Unfortunately, the only way I can see doing it right now would be for it to generate a "blank" sculpt mesh (probably a sphere, at least for the first generation of SL sculpt prims, as Qarl has indicated sheet, cylinder and torus topologies are in the works for later versions), the verts of which you can then move around as desired, then have it generate the sculpt map, which you then upload to SL and apply to a sculpt prim. You wouldn't be able to directly load an existing model (that wasn't saved from a previously generated sculpt shape, that is) and just produce a sculpt map, though you could load one and try to "duplicate" it using a sculpt mesh.

From what I have read of the sculpt-prims I think starting with from a sphere with 1024 vertices will be the best way to create them in any program. That way you know what you are starting from, and there is no worrying about missing vertices or holes in the shape.

If you can use AutoCAD, pick up the trial for Rhino. It was originally created as an extension for AutoCAD, so it's very, very easy to transition. However, it is almost completely NURBS though, so if you try to do polygon modeling, it's still a difficult transition (I still can't do it to save my life).

I'm a big fan of Rhino, also....and now somewhat speculating how I'll get objects out of there and into SL as sculpted prims. Not sure how difficult it would be to do a similar script to the Maya exporter.

What limits are there to the sculpt prim?
So can faces intersect?
What is the best sphere shape to start with? like a 24 segment sphere? which is the highest LOD of the sphere in SL.

It was stated it is based off a sphere. Then this sculpt texture basically distorts how the sphere is distorted using the RGB values to make XYZ values for each vert. So we are not talking a very high level of accuracy. Since there are only 256 values for each color range. So the larger you make the prim in SL the less accurate it will be. This will be great for organic object. Also remember the texture is going to be compressed when it uploaded so this will alter the RGB values slightly which will then change your mesh a little.

I have managed to manually create these textures in Max. Buy mapping R G B gradient on the final object then Rendering to a texture or also known as texture baking.

According to Qarl, it's a 32x32 grid mesh. For a spherical topology, I'd think that'd mean 32 longitudinal segments and 31 latitudinal. This can be confirmed once sculpted prims go live in the beta grid.

[Edit: ...Which they just did. Ok, it's 32 segments in each direction, so now I'm wondering if the vertical positions aren't inherently interpolated.

Min/Max greyscale values on each channel map to an offset of -1/+1 on the corresponding axis (multiplied by scale), not -0.5/+0.5 as I'd initially assumed. Therefore the max size of a sculpted prim is a 20m cube... but the collision hull will still only be a 10m dia. sphere. Interesting.

Ok, not quite +1. Max color value is 255, but it's out of a 256 range (the old fence/posts conundrum), so max positive displacement is actually +0.992. Formula seems to be:
Value / 128 - 1

Texture coordinates do not match up to sculpt map coordinates. Sculpt map is wrapped right edge to left edge, texture map is wrapped bottom edge to top edge (by default). Applying the same texture for both, then rotating the texture map 90 and flipping vertically will show the true pixel to vertex correlation.

Attached are SL recreations of my Cube/Sphere MilkShape samples earlier in this thread.
/Edit]


Eh, for an object with a 10m cubic bounding box, that's still within 3.4cm.

I dunno, you can make some pretty complex shapes with well below 1024 vertices... guess you just need to keep in mind how to orient it to get the best result from a displaced sphere. Heh. The proposal of sculpted prims drove me back to both Secondlife and using Blender xD

Amanda Levitsky been playing a bit with sculpted prims using Blender and thought she'll share what she learned, since people seem to be interested in how to do this:

http://amandalevitsky.googlepages.com/sculptedprims

Man, all you folks playing without me! It's not fair!

I'm currently on the job and I don't know how long it will take. When I'm done and have time to play, I will *so* catch up in a big way.

Thanks for the images and all the info peeps, they are certainly a help.

Please tell me you used a Blender exporter to get those in world. And if so where do I get one?

Very nice work by the way Destiny and Amanda, thanks for the tute.

You don't need an exporter with Amanda's tutorial, she has instructions on how to set the image up so you can just save it and upload it into SL.

There's another blender file and tutorial out there (link's in the Wiki) that starts with a sphere. I was able to make some funny shapes by lattice-deforming the sphere, then baking that shape into the texture.

The hard part (getting the UV to unwrap right so the sphere becomes a square, and setting up the channels) is already done for you in this file, so all you do is shape the sphere and hit 'bake'.

Yesterday was a crash course in 3D modeling. Yesterday morning I had no idea what a lattice was

Anyway... if someone could explain exactly how one gets the square texture from a sphere, that would be cool. Amanda's tutorial starts with a cylinder, and in that case it's easy to see how it unwraps based on the seams selected, but I don't understand how to do it with a sphere.

Ok just back from the beta test grid.

And there are sculpted prims all over the place! People have left plenty of examples of their
experiments.

At first I was applying the texture wrong, (there are some free samples on the wiki) by
trying to use the texture tab.
You can see in the above pic a cube that has the rgb colors applied from the texture tab.
That is an example of the wrong way.

To apply the sculpt texture go to the 'object' tab drop down menu and choose sculpt.


Here is a prim with a rounded cube that I stretched to look like a couch cushion.
The texture is simply a shade of gray with the 'checkered' bump on it.

One thing I was a bit disapointed about is that the path cut and similar tools are not available.
But you can stretch and and translate but that is about it.

The exterior texturing is also very weird and off, so for best results your texture will need
to be designed for the object from the start.

Also of note,

you can apply any random texture to the prim in the object tab. The results vary yet they
all look like a jumble of jagged edges so far. Could have some possible uses with more experimentation, art or weird foliage perhaps.



It is the object directly in front of my av.

I tried to explore beta again this morning but I can't stay in for more than 5 minutes at a time without crashing, and seems more people are interested in voice chat than the sculpties... that mess you took a snapshot of was there since yesterday morning...
I haven't seen anything totally amazing by anyone yet.. maybe they are just holding out til the live release But I would love to see more of what people are doing with sculpties

Flex is currently broken in beta so take off all flex objects, and run if anyone comes near you wearing flex, it will crash you.
I've seen some nice things already in beta. I can't wait until it make it to the main grid.
You can see some of the creations in the gallery section of forums

Flex is currently broken in beta so take off all flex objects, and run if anyone comes near you wearing flex, it will crash you.
I've seen some nice things already in beta. I can't wait until it make it to the main grid.
You can see some of the creations in the gallery section of forums

Nurbs is an outdated, resource inefficient, and difficult modeling method. It definitely has its uses but it's really the last thing you'd want to use for creating sculpties. Polygon and subdivision modeling is going to be a much better choice.

OK, it would be great fun to build Sculpties in Wings3D
(do you know something better for subdivision Surfaces ?)
But how do you convert the Object to a Geosphere umm... Topology (?)
I spent a few Days thinking about that, but have no Idea how to solve
this Problem.

I really haven't played with sculpties yet but I don't think you need to convert the topology at all. You just have to keep in mind the resolution of the sculpt map. Anything more than 1024 polys will be too detailed for the sculpt map to define since there aren't enough pixels. The exporter for creating the sculpt map turns the XYZ surface positions into RGB. The actual topology shouldn't really matter. I don't really know of any great free modelers so Wings looks pretty good for what it is.

Exporting Random Meshes is a Problem.
You know, the Sculpt-Map contains 2 Kinds of Information :
1. The Vertex Positions, as RGB Colors. Easy.
2. The Triangles. See this Page .
I wrote a simple Program to convert .obj to a Sculpt-Map.
It works fine if i use it on a 32 x 32 (vertices) Object, like a Geosphere
or the default NURBS Sphere from Blender.
If i try it on the Blender 'Monkey' or any other Random Object,
the Triangles get mixed up.
1 Row of Pixels = 1 Row of Vertices that get connected to the row below
and it wraps around.

Good point. I can see how that would be a problem. I'm hoping I can use Max's projection cage feature and not have to worry about it. The way it works is that you have the base model that you're creating a normal map for and inside that you build the more detailed version. The app then raytraces along the surface normals of each polygon in the low poly mesh and records hits on the detailed model creating a map that stores the difference between the two meshes. That map is then used by game engines (or rendering engines) to render the low poly model as if it were the high poly model. A normal map is the same principle as a sculpt map, only it stores surface normals while a sculpt map stores surface positions. I'm afraid it will take someone much smarter than me to create an exporter for Max, and since I haven't experimented with creating sculpties at all yet I may be way off base.