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13.1 Skelegons - Part 1
 
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MODELER, SKELEGONS?

This tutorial covers skelegons. Skelegons allow you to create a bone hierarchy in Modeler.

Let me say right at the onset that this tutorial is going to introduce you to skelegons, showing how you create them, place them, name them, and give a weight to the polygons around that skelegon.

IMPORTANT - When you know that you'll be creating skelegons for your model, ALWAYS create the model with its arms out to the sides. It will make things easier if the arms are perfectly perpendicular to the body.

Also, make sure that the legs are spread away from each other at about a 40 degree angle.

I'll be showing why this is true in upcoming tutorials.


MODELER, WHAT ARE SKELEGONS?

Skelegons are a polygon type which can be added to your object in Modeler and LOOK like bones. You can create a complete skeleton out of these new type of polygons.

However, skelegons AREN'T bones. They only act as a placeholder for bones once you bring the object into the Layout program and do a 'Convert Skelegons to Bones' on them.

Once you've converted skelegons to bones in Layout, you can't reverse the process, modifying the bones in Layout and converting them back into Skelegons.

In Layout, bones allow you to animate anything from a toaster, to an arm, to a body. You set up a relationship of motion just as the bones in your arm do.

You move bones in Layout to deform the object just as moving bones in your body deforms your arms and legs from their present positions.

There are a lot of clear advantages to using Skelegons instead of building bones one-by-one in Layout. If your boss suddenly tells you that he wants the legs to be longer, and the arms to be shorter, you can do that easily with Skelegons.

LightWave has really scattered the information about how to use skelegons all over the book though, and they don't give you the clues that let you properly use them. This tutorial will hopefully be that key for you. I will make the pertinent text which will turn that key VERY LARGE so you won't miss it.

There are a LOT of people out there struggling with skelegons because of this.


MODELER, CREATING SKELEGONS

Press the space bar to complete any operation you were currently doing, and make sure you have saved whatever you were working on before. Do a 'Close All Objects' from Modeler's 'File' menu.

From the 'Create' tab, 'Elements' section, select 'Skelegons'.

In the 'Back' viewport click anywhere, clicking somewhere else. The first time you click a circle with a crosshairs in the middle of it will appear. The second time, a strange double-sided pyramid with it's smallest pyramid towards the first point you placed will appear. This is called a skelegon.



Now, click one more time. A second skelegon will be created.



Click in the bottommost circle with the left mouse button and hold the button down. Drag the mouse to the left and you will see the last skelegon rotate to the left and change length as you move up or down.



Before skelegons were invented, people had to create their object in Modeler, creating and connecting the bones one-by-one in Layout, which was a VERY annoying way of having to create a skeleton. See how easy it is to create chains of bones?

And, before, bones had to be saved in the program where you set up the world rather than kept inside the place where the object was. Since bones are part of a body, why shouldn't they be part of the object just as they are in the body?

Now, click one more time to the left of the last circle.



Now, click with the left mouse button, hold it down and drag it on each circle one-by one beginning with the bottom circle. You will see that all skelegons below a circle move when you move any circle.



Any circles above that circle stay steady and don't move and the skelegon just 'above' a circle changes its size.


MODELER, THE FIRST CIRCLE IN A SKELEGON CHAIN IS DIFFERENT

The first circle in a skelegon chain does a different thing. When you try and move the first circle, a new skelegon will appear. It will lengthen as you pull and the rest of the skelegons will move, not changing position relative to each other.



This can be an annoying aspect of skelegons. Be careful where you place that first skelegon, as it is a pain to move.

Press the spacebar to finish the skelegons and exit from the Skelegon tool.


MODELER, PRESS SPACEBAR TO COMPLETE SKELGONS



They now look just like any polygon would.

Enter Polygon mode by pressing CTRL-SHIFT-H and make sure that no polygons are selected.

Click the left mouse button and drag your mouse across the skelegons so that one of them becomes highlit.



Press the ']' key to select connected polygons and the entire chain will become selected.




MODELER, DELETING SKELEGONS

It's simple to remove skelegons, just press the 'Delete' key while the skelegons are highlit and they all disappear.


ADVANTAGE OF SKELEGON CREATION OVER BONES

One great advantage of creating skelegons in Modeler rather than assembling Bones in Layout is you can assemble an entire skeleton, naming each bone, and because skelegons are just like polygons you can select the entire skelegon structure and paste it into its own object to use again later, with modifications, in another similar model.


LAYOUT, CREATE ARM'S SHOULDER SKELEGON

To illustrate, I will be using the arm that you made in the last tutorial, so from the 'File' menu, do a 'Load Object' and load 'arm.lwo' into Modeler.

Arrange the 'Back' and 'Right' views like this...



Select from the 'Create' tab's 'Elements' section.

Click the left mouse button to the right of the shoulder in the 'Back' view and a crosshairs with two circles around it will appear. Hold the mouse button down, dragging it to the left. Let go of the mouse at approximately the center of the deltoid muscle. The first skelegon appears.




MODELER, AUTOMATICALLY ASSOCIATING/CREATING WEIGHT MAPS FOR EACH SKELEGON

Press the 'n' key to bring up the 'Numeric: Draw Skelegons' requester. From the 'Actions' drop-down pick 'Activate'. Under the 'Name' box, type 'Arm'. Keep 'Digits' checkmarked. Click the 'Fill Weight Map' checkmark and change the 'Weight Map' name to 'Arm' also. Keep the Falloff at 'Inverse Distance^8'. Click the close gadget.



A Weight Map tells LightWave which polygons are affected when the skelegon is moved. Keeping the 'Digits' checkmark checked will cause LightWave to automatically create a new Skelegon name and Weight Map name as Arm01, Arm02, etc.

Each time that you click the left mouse button while in 'Create Skelegon' mode, it will now create an associated Weight Map. Click the close gadget of the requester and you'll see the name 'Arm01' appear in the drop-down menu at the bottom right of your window.



The 'W' at the left of the drop-down menu stands for 'Weight Maps'.


MODELER, CREATING BICEP SKELEGON

Click the left hand mouse button at approximately where you think the elbow would be. A second skelegon will appear.



Move the mouse to the wrist and click with the left mouse button. A third skelegon will appear.



Press the spacebar to finish the skelegons. This will cause it to exit from the 'Draw Skelegons' mode. The cyan color will disappear and the skelegons will become very difficult to see as they mix in with the other polygons of the arm. From the 'File' menu select 'Save Object' or press the 's' key and save it as 'arm.lwo'

Nothing seems to have happened when you look at the 'Weight Map Drop-Down Menu', but if you left-click on where it says 'Arm01', you'll see that it also created an Arm02 and Arm03 Weight definition.



The skelegons are contained within the arm when we look to the 'Right' view, so lets just leave that the way it is for the moment and see if it works right before moving anything.


LAYOUT, 'SKELEGON TREE' PANEL

Select the button from the 'Elements' section of the 'Detail' tab. This panel shows you both the skelegon names, and the associated Weight Map names.



Notice that Arm02 is indented beneath Arm01. This means that the Arm01 skelegon is the 'Parent' of the Arm02 skelegon. It can also be said that Arm02 is the 'Child' of the Arm01 skelegon.

In the same manner, since Arm03 is indented beneath Arm02, that means that the Arm03 skelegon is the 'Child' of the Arm02 skelegon (or, in other words, the Arm02 skelegon is the 'Parent' of the Arm03 skelegon).

Here are some quotes from the manual which relate to the parenting of bones. Since skelegons are placeholders for Layout's bones, it's not surprising that you see parent/child relationships with skelegons.

Parenting:

"Parenting (see Chapter 11) can dramatically impact the results of rotation."

Parenting refers to LightWave's ability to set hierarchical associations between items in a Scene, much like files use directories.

These relationships can grow into a complex hierarchy with multiple items parented to an item and the child items being parents themselves of other items.

Generally, the parent item will have some level of influence on its child, whether it is position, rotation, size, etc.

The child can also be a parent to another item.

You can parent just about anything to anything. That is, lights can be parented to objects, objects can be parented to a camera, and so on. You can also parent items to bones; however, bones must remain under the object they relate to."

IMPORTANT - The child inherits the position, rotation, and scale of its parent. You can also animate the child independently, but its movement will be added on to the parent's.

With Skelegons, the Modeler program is automating the parenting process for you.

The associated Weight Map name must equal the Skelegon name for the Layout program to automatically associate the map with the proper skelegon.


MODELER, CHANGING SKELEGON AND WEIGHT MAP ASSOCIATIONS

You should now change the skelegon names and associated weight map names so that they are more understandable to you. You can keep the 'Arm' part of each, adding a last part so each makes more sense. Double-click with the left mouse button while pointing at each name one-by-one and a requester will appear that will let you change the names to ArmShoulder, ArmBicep, and ArmForearm.

Here, I've double-clicked on and changed each of the left-hand side's skelegon names.



The Weight Map name MUST equal the Skelegon name. So, I now click on Arm01 under where it says 'Weight Map' and change the Weight Map associated name to 'ArmShoulder'.



Click 'OK' to change the Weight Map associated name.



After you've completed changing the Skelegon names to equal the Weight Map associated name, close the 'Skelegon Tree' window.


MODELER, CHANGING WEIGHT MAP NAMES

A VERY IMPORTANT THING TO NOTICE is that you AREN'T changing the name of the Weight Map that Modeler created for you. You can prove that by looking at the 'Weight Map Drop-down Menu'. It still says 'Arm01'.



If you open the menu it still says Arm02 and Arm03...



So, you're not done yet. Just because you changed the associated weight map name, doesn't mean LightWave was smart enough to rename the names which it might have found if it were smart enough to LOOK, but it doesn't look so it's your responsibility to do it.

You'll have to change the three Weight Map names. First, select Arm01 from that drop-down menu.

To rename the map, select the button from the 'General' section of the 'Map' tab.



A 'Rename Vertex Map' requester will allow you to change the name of the Weight Map.



Change them one-by-one. Change Arm01 to ArmShoulder, Arm02 to ArmBicep and Arm03 to ArmForearm.



Make sure that the actual Weight Map names equal the names you associated with the skelegons in the 'Skelegon Tree' requester (compare the names in the Weight Map drop-down menu with the names in the 'Skelegon Tree' requester).

Note that you can also delete a weight map from the drop-down menu by selecting that name and choosing the button from the 'General' section of the 'Map' tab.


MODELER, 'EDIT SKELEGONS' MODE

To return to the 'Edit Skelegon' mode where the skelegons are cyan-colored, first enter 'Select Polygons' mode with CTRL-h, make sure that all polygons are deselected, highlight the 'Lowest' skelegon (the first skelegon that you created). It will turn yellow just as any other polygon might do.



From the 'Other' section of the 'Detail' tab, select the button and the cyan color will return.



You could readjust the pivot points of the elbow, or wrist, or shoulder this way, by clicking in the circles with the left mouse button and dragging the mouse in the 'Back' or 'Right' viewports.

Save your work by pressing the 's' key of if you hadn't yet saved it, do a 'Save As' and call it arm_02.lwo.

That should at least give you a beginning point to start from, with some clues to go by when you run into problems with skelegon/bone conversion.

Next, we'll be looking at how 'Bank Rotation Handles' allow you to control the angles of bone's once you've converted skelegons to bones in Layout.

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