|This is the second part
of the Simple Walk tutorial. The three parts are:
1) Building the body parts,Here you will learn how to make the skeleton for your character, and how to attach the body parts. You need to have the objects from the first part in order to do part two. If you want to start with pre-built parts, you can get them here in an Anim8or project .
|The skeleton you will make is very simple. It has two legs, but not much of a body. The joints of the legs will be flexible like human legs, with knees that bend like humans. But when you flesh out the skeleton, all of the head, eyes, feathers and such will be fixed. Of course you can add more bones and joints as you wish for greater movement. Then, in part three, you build a walk cycle and animate your character.|
|Building the Skeleton|
|All skeletons start with a root bone. Everything else is attached to the root as a child. Select Mode->Figure from the menu to enter the Figure Editor. This will open a new figure and show it root in the center of the view. It's a good idea to name your character something meaningful, like "Robin". Use the Settings->Figure menu command.||
|Make sure that you are in
the front view. Select the root and then add a right hip bone
by clicking on the Add Bone button
in the tool bar. (It is the upper one of the two. The lower
one toggles the visibility of bones in the workspace.) Click on the
of the root and drag up just over 1 grid line. This adds and selects
a new bone. New bones are added pointing in the same direction as
their parent, so you need to rotate it to the left. Select the Rotate
and, using the left mouse button, click on the new bone's tip and
rotate it so that it's pointing to the left. The left button rotates
bones in the plain of the screen, the right one around their length,
and the middle button rotates them out of the screen.
Double click on the bone and give it a name of "Right Hip" and a length of 11. Now add a child to the hip in the same way. Name it "Right Thigh", rotate it to point straight down, and give it a length of about 26.
|If you make a mistake and
add an extra bone, you can delete it with the Edit->Cut command.
This removes all selected bones and any objects that are attached to them.
If you delete a bone that has any children, they will be moved up and attached
to the deleted bone's parent.
Now add another bone of length 26 below the thigh, and name it "Right Shin". Leave it aligned with the Right Thigh. Add one final length 6 bone "Right Foot" below the Right Shin. You need to rotate it so that it is facing towards you, so switch to the side view to see better. Rotate it so that it's pointing to the left. Your skeleton should look like the one shown in the Ortho view at the right.
|Now add the left leg in
the same way. Notice that you must first select any bone before you
can give it any new children, or before you can rotate or scale it.
If Anim8or didn't require bones to be selected, it would be too easy to
accidentally edit the wrong bone.
Add a new bone to the root pointing straight up. Give it a length of 29 and name it "Spine". Add one final bone to the Spine also pointing straight up, named "Body". This is where you will attach the head, eyes, feathers, etc. It's length isn't too important since it is only used as a reference coordinate system for the head.
Your final skeleton should look like the one at the left. Now is probably a good time to save your work with the File->Save or File->SaveAs command.
|Adding Body Parts|
|Next you'll add all of the visible "body parts" to your character. These will be the only things that appear in you final images and animations. For the most part they are objects you built in the first part of this tutorial, but the legs will be made from simple tubes and balls that can quickly be added in the Figure Editor itself.|
||First build the legs.
Select the Right Thigh bone. The select the Build->AddCylinder command
from the menu and set the start and end diameters to 2 in the dialog box.
Don't worry about the length, it will automatically match the bone's length.
Click OK and a cylinder will be added to the right thigh.
Normally objects in the figure editor appear as transparent with the bones visible inside. You can hide bones and objects by toggling these buttons on the toolbar. When the bones are hidden all objects are shown as solid.
||To change the color of the
new thigh, select the Options->Materials command from the menu to show
the Materials Toolbar. Add a material for the legs and apply it.
I used the same color as the Foot (247, 207, 71) in the first part of this
Stiff tubes don't make very good legs by themselves. When the joints bend gaps appear. So we'll add a ball at the ends to hide the gap. Select the right thigh bone again, then select the Build->AddSphere command from the menu. Set the diameter to 4, and then apply the same color that you gave the cylinder.
||Now select the Right Shin
bone and add a similar cylinder and sphere to it as well. Make sure
that you select the bone before you add something, or it won't work.
For this bone, we also need to cover the joint between the shin and foot. So after you add the sphere, move it down to the bottom of the shin bone with the left mouse button. Then add a second sphere for the knee.
The only thing left for this leg is the foot. Select the foot bone and then use the Build->AddObject command to add the foot that you made earlier.
Add the same things to the left leg, and your legs are finished.
|Building the Body|
|Making the bird's body is fairly simple since it isn't animated. All you have to do is add all of the necessary parts to the Body Bone and move them into the right positions.|
|Start with the body itself, since everything else is positioned relative to it. Select the body bone, then select Build->AddObject and pick Body. It should be positioned with it's bottom just below the axis. If it doesn't look right you can adjust it's height by changing the length of the Spine bone.||
|Add the beak next.
When your first add it, it won't be visible. It's inside the body.
But, the bounding box should show up since it's automatically selected
when you add it. If it doesn't you probably forgot to select the
Body bone before you added the beak.
Switch to a side view and move it to the front of the body (towards the left) and down a bit. Position it so that the point where the two halves of the beak meet is just barely outside the body. By doing this in the side view, you can easily keep the move in the same plane as the center of the body and you won't have to worry about left to right misalignment.
|Now add the eyes, one at a time. Using the side view, move them to the left until they are visible, then switch to the front to position them on the face. If you have trouble selecting them with the body directly behind, you can always hide the body with the Edit->Hide command that hides any selected objects. Since this is a fixed face, you might want to rotate the eyes to the side for a better pose. In a fully animated character you would keep them looking forward and move them in the animation.|
||There's just the feathers
left to add. Select the Body bone and add the first one. In
the side view you can move the feather straight back and it's in place.
To make a wing out of 3 feathers, start in the side view. You might want to hide the body so you can see what you're doing a little better. Add a feather, then rotate it so that the big end is pointing straight back. Use the right mouse button so that the feather stays in the plain of the screen. Add a second and rotate it so that it's pointing about 30 degrees up from the first feather. Add a third pointing 30 degrees down.
Now select all three feathers. You can use the right mouse button to select more things and keep the old ones selected. Switch to the top view and rotate all three feathers to the right about 15 degrees. Select the Edit->ShowAll command to un-hide the body and move all three feathers to the right and down until they are tangent to the body.
Now, do this all over again, but for the left side, and your bird's body is done.
|There is one more thing to do in the Figure Editor before your character is complete. You need to specify how much, and in what ways, each joint is allowed to move, and what is the "at rest" position.|
|Start with the Right Thigh. Select the bone and then show bone axis in the toolbar. It might be easier to see what you are doing if you use the Ortho view and hide objects . Each selected bone shows three arrows, one for each axis. The x is in green, the Y in blue, and the Z in violet. Since you want the right leg to bend forwards and backwards, you need to allow it to rotate around the X axis. Double click on the right thigh bone to show its properties dialog.|
|Check the Free X joint limit
box and set the minimum value to -90, the default to 0, and maximum to
90. Click OK and your character's skeleton will show an arc indicating
how it's thigh joint can move. In the image on the right, the Spine
bone has been hidden (select it, and then Edit->Hide) to make the arc more
Note: In the Figure Editor bones are always shown with all joints at an angle of 0 degrees. You should try to make the default angle 0 for all flexible joints when possible, so that the Figure Editor shows a reasonable pose for your character.
|Next select the Right Shin.
Since this character will walk like humans, with the knee only bending
backwards, give it a minimum angle of -135 degrees in the X axis, and 0
for both the default and maximum.
A foot can bend up a little, but down a lot more, so give the Right Foot joint limits of -90 and 30, with 0 for the default.
Add the same flexibility to the joints of the left leg and your character will be able to walk!
You can also allow your character to turn its body (head?) if you like. Double click on the Body bone and enable the Y axis with a range of -90 to 90 degrees or so. The right shows the final skeleton with several bones selected to show how they can move.
|Now you're ready to go to Part 3 of the tutorial where you will bring your character to life!|
|To download an Anim8or project containing the objects built in the first part of this tutorial, and the character form this part, click here: tutorial_simplewalk_2.zip.|
|This page was last updated on November 1, 2001.||
Copyright 2001 R. Steven Glanville