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Aside From Textures, What Are Avatars Made Of?


JanuarySwan
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Aside from textures, what are avatars made of?  For instance, take all the textures off and just have a gray form and explain to me what it is made of please.

Next, how does an avatar move (teleport) from place to place?  What is moving the avatar?   And, by move...I don't mean the animations...I mean teleporting.

These questions are coming from a non-Geek so simplifying would be helpful if possible.

Thank you.

Love,

Jan

Edited by JanuarySwan
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Triangles. Lots and lots of triangles.

wireframeavatar.thumb.png.7ae750689cf059ec78afd13709b3129e.png

Triangles. This is what an avatar looks like underneath the textures.

Underneath that, there's a "skeleton", with a set of "bones" and joints. The vertices, which are the points where the edges of the triangles meet, are connected to the skeleton so that they follow the movements of the bones. The bones move as the joints rotate. The joints rotate to follow animation files, which contain lists of times and positions to move the skeleton through "walk", "run", "sit", etc.

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33 minutes ago, JanuarySwan said:

Aside from textures, what are avatars made of?  

Pixels, binary numbers, computer coding, and scripting? I’m sure someone can give you a more long winded explanation, but that’s the gist of it. 

 

~Vael

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Movement in world consists of moving and rotating the "root" point of the avatar around. Everything else is an animation. To the system which runs Second Life, an avatar is a "capsule", a cylinder with rounded end caps.

How do teleports work? Each region of SL is run by a program in a computer in a data center in Arizona. There are thousands of computers there doing this, for the tens of thousands of regions. When you're moving within a region, the program for that region handles the avatar, and sends messages over the Internet to the viewer such as "Avatar, move to <124,354,45>". The viewer then does the graphics work to make that appear on screen. In the other direction, your arrow keys and mouse clicks are sent to the server so it knows what you're asking.

When you do a teleport, the program for the region you are in sends all the info about your avatar to another computer in the data center, the one handling the region you are going to. The sending region computer tells your viewer to start talking to the server for the new region. The viewer makes that connection, and then you see your avatar in the new region. It's sort of like going to a new web page, although not really that similar.

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1 hour ago, animats said:

Triangles. Lots and lots of triangles.

wireframeavatar.thumb.png.7ae750689cf059ec78afd13709b3129e.png

Triangles. This is what an avatar looks like underneath the textures.

Underneath that, there's a "skeleton", with a set of "bones" and joints. The vertices, which are the points where the edges of the triangles meet, are connected to the skeleton so that they follow the movements of the bones. The bones move as the joints rotate. The joints rotate to follow animation files, which contain lists of times and positions to move the skeleton through "walk", "run", "sit", etc.

That's amazing.  

Where do the triangles come from?  

And, who was the first to generate triangles like that in the picture?  Do you know?  

I wonder how somebody came up with this idea.  I knew it involved math somehow too but wasn't quite sure what the math was doing exactly.  

The teleporting amazes me.  But, from what I understand of what you said below about teleporting...it's computers relating to the viewer and a mathematical sim number to make placement of the avatar?  Is that somewhat correct?

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This image, from a Blender tutorial, shows a wireframe mesh getting rigged with bones.

character.thumb.jpg.5c22ce33c85e4a6b3f55aec8190f7d3f.jpg

As Animats says, any 3D character model, including Second Life avatars, consists of:

  • A skeleton.  This is not the same as the bones in your RL body.  3D bones are a way to let the animator visualize and control how the character mesh will deform when it is animated into various positions.
  • A mesh.  This is a structure composed of polygons, usually either four-point polygons ("quads") or triangles ("tris").  Triangles have the advantage of always remaining planar, no matter how their defining points are moved.  Like bones, a mesh isn't "really" real.  It's a mathematical construct given visibility in a 3D modeling program to allow the model creator to see and manipulate it.
  • Textures.  In itself, a mesh isn't visible.  The program has to know what sort of surface to display.

If you hit CTRL+SHIFT+R (or is it CTRL+ALT+R?  I forget!) when you are in world, your viewer shifts to "wireframe" mode and you can see the mesh of your avatar, and objects too.  You'll see a whole lot more of these polygon objects if you ever start modeling in a 3D program like Blender.  This method of depicting a 3D model as a polygonal mesh has been used by 3D creation programs for over 20 years.

In Second Life, avatars require four components in order to even exist: A shape, a skin, eyes, and a system hair base.  The shape can be controlled with the avatar appearance sliders.  When you make yourself taller or shorter, you are actually manipulating the avatar bones.  These sliders are the only way we can alter the system avatar's bones; you aren't allowed to directly mess with them, or add or delete bones.  The skin is a texture...actually four textures, applied to the head, arms, torso, and legs.  The eyes are another texture, applied (you guessed it!) to the eyes.  The hair base controls the eyebrow shape; in addition, it can be used to create some (really awful looking) system hair.  The hair control sliders are nearly always set to zero, giving the hair base its other name, "baldy", or "bald cap".  You can't take off any of these four essential components, like you can other avatar parts and accessories; but you can replace them with another item of the same type by Wearing the new item.

Edited by Lindal Kidd
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3 minutes ago, JanuarySwan said:

Where do the triangles come from?  

And, who was the first to generate triangles like that in the picture?  Do you know?  

Now we start getting into math.

Each triangle is a 3X3 matrix.  3 points with X Y an Z coordinates each.

[-1,0,3]
[0,1,2]
[1,0,1]

For more on identity matrices, matrix multiplication, vector math, translations and rotations, you will need a class in Linear Algebra.

 

As far as who was first?  probably Ada Lovelace ...

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I'm finding the history of 3D modeling to be difficult to pin down.  However, Allen Hastings and Stuart Ferguson created software in 1988 that would become LightWave3D.  LightWave was (and still is) marketed by NewTek.  The first versions ran on the Commodore Amiga computer!  One of the first major commercial uses of LightWave was in the TV series, Babylon 5.

Going further back, William Fetter, working at Boeing in the 1960s, created and animated human figures.  Some credit him as the originator of computer 3D modeling and animation.  In 1972, Frederick Parke created a model of a human face, and in 1973 Edwin Catmull created a model of a human hand.  Catmull would eventually become one of the founders of Pixar.

The best way to understand 3D modeling and animation is to do it.  There is a very capable software, Blender, available for free, and lots of YouTube and web tutorials to get you started.  Just don't expect to start making models of human beings right away!  This type of software can be learned, but it will take time and dedication.  Start slow, and work steadily...an hour or so a day.  You may find it to be as addictive as Second Life!

The best way to understand the underpinnings of teleports...the real guts...may be to download a copy of OpenSimulator, and then get into the actual code.  OpenSim is a free version of virtual world simulation software very much like SL.  With it, you can set up a virtual region on your own PC, and visit it with a Second Life viewer. 

Edited by Lindal Kidd
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If you're Tom Cruise, you jump in a helicopter and make a daring landing on the moving bus.  Armed only with a pocket knife and your wits, you first unmask the terrorists who are on the bus.  You then disarm the bomb, take control of the bus (which has now somehow lost its brakes and steering and is careening down the highway out of control), and save the day.

If you're Chuck Norris, you step out in the highway in front of the bus, grab it by the grille, and fling it 10,000 feet into the air.  When it explodes, it takes out the plane carrying the terrorists to safety.

(If you're Lindal Kidd, you are easily distracted by thread derails and enticed into flights of fancy!)

Edited by Lindal Kidd
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59 minutes ago, Lindal Kidd said:

If you're Tom Cruise, you jump in a helicopter and make a daring landing on the moving bus.  Armed only with a pocket knife and your wits, you first unmask the terrorists who are on the bus.  You then disarm the bomb, take control of the bus (which has now somehow lost its brakes and steering and is careening down the highway out of control), and save the day.

If you're Chuck Norris, you step out in the highway in front of the bus, grab it by the grille, and fling it 10,000 feet into the air.  When it explodes, it takes out the plane carrying the terrorists to safety.

(If you're Lindal Kidd, you are easily distracted by thread derails and enticed into flights of fancy!)

I'd ask myself what would MacGyver (RDA) do... then do eet.

DxpPCk-WkAAOtES.jpg

Edited by Selene Gregoire
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