You can either use a character of your own, or you can load the "KNIGHT.BLEND" file from the CD-ROM.
When designing your character, model it up so that the arms are stretched out to the sides, with the palms facing down. The legs should be straight with the feet flat on the floor (Fig. 1).
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Figure 1 [images/Ika/notes3.tga] |
There are three main sets of components involved in the character animation setup process. The mesh, the skeleton, and the controls.
The mesh is the actual model geometry that is rendered. The mesh is deformed by the skeleton that is composed of the IKAs and Empties that define the deformation envelope. To simplify the animation process, the skeleton is often manipulated indirectly with a series of control objects.
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This makes it easy to show or hide layers to reveal just the mesh or the skeleton, to easily locate the control empties or to hide the deformation objects. Depending on the complexity of your skeletal system you may want more or fewer layers. Putting a character's finger IKAs on a layer of their own would it much easier to select and focus on the small bones without accidentally selecting items in the rest of the character's skeleton. |
In a character setup, most of the major IKA chains will be left in IK mode.
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Though it is possible to directly manipulate the location of an IKA chain's effector, it is often better to use an empty as an effector parent and move that instead. This way it is possible to see where the IKA chain is trying to go, and to set targets that would not normally be reachable by an IKA chain (such as having a character's arms stretch out to touch an object that is out of reach).
When making another object the parent of an IKA chain, a requestor will appear with the message EFFECTOR AS CHILD? To designate the object as an effector parent, click on the message, or press ENTER . To dismiss the requestor (and therefore set up a normal parenting relationship), press ESC or move the mouse away from the requestor.
Note that effector parents only have an effect if the chain is set to IK mode.
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Figure 2 [images/Ika/notes5.tga] |
To solve this problem, we place an extra bone at the root of the main chain with the same facing, but rolled 90 degrees. This new IKA becomes the child of the main chain's root, and becomes the limb-parent to the main chain (Fig. 3).
Both the chain and the limb-parent should use the same empty as an effector parent.This technique works very well for shoulder and hip joints. If you are going to be rotating an IKA operating in IK mode, you can place an empty at the root of the IKA and make it the parent of the IKA.
Note that when you are building the skeleton, the joint IKAs should not be included in the calculation.
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Figure 3 [images/Ika/notes1.tga] |
Sometimes you may find that the IKA solver leaves your limb in an awkward orientation. This happens most frequently with the arms. One way to solve this is to use an empty to control the roll of the limb.
Create an empty and position it at the base of the limb (you can move the cursor to the exact location of the base by selecting the IKA and pressing SHIFT+S >>CURS->SEL. Clear the empty's rotation by pressing ALT+R >>CLEAR ROTATION. Make this empty the parent of the limb you wish to control, and then make it the child of whatever the limb was attached to. Fig. 4 shows a rolling empty applied to a 360 degree joint.
When animating using a rolling control, make sure you clear the rotation before setting a new key. This will help prevent problems such as limbs that twist through impossible angles.
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Figure 4 [images/Ika/notes6.tga] |
It is possible to roll a single limb in an IKA, rather than the entire chain, though it takes a bit more work to set it up. This is useful for joints such as elbows (The elbow is responsible for the rotation of the hand: try to rotate your palm while holding your wrist with the other hand).
Start by creating an IKA chain (Fig. 5). The limb highlighted in green is the limb to which we want to add the roll.
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Figure 5 [images/Ika/notes20.tga] |
Now add some single-segment IKAs: one for each limb of the arm chain. Leave these new segments in FK mode and make the appropriate limbs from the chain the limb-parents of the appropriate segments
Fig. 6 shows the placement of the new bones. The blue and the green bones are parented to the main chain (represented in grey). The pink bone is left unparented.
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Figure 6 [images/Ika/notes21.tga] |
Add an empty at the base of the final segment, and make sure the Z-axis of the empty points along the bone. Make the empty the limb-child of the final limb of the chain, then make the segment the child of the empty (Fig. 7).
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Figure 7 [images/Ika/notes22.tga] |
When calculating the skeleton, use the three single segments, rather than the actual arm bone.
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Figure 8 [images/Ika/notes23.tga] |
To rotate the empty along it's z axis, select it and press KEYPAD* . This sets the view perpendicular to the object. Rotating the empty in this view will roll the bone along it's length. To return to the previous view, simply press the appropriate button on the keypad.
The Root bone is placed at ground level between the character's feet and should be fairly large to easily distinguish it from the rest of the skeleton (Fig. 9).
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Figure 7 [images/Ika/notes7a.tga] |
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Figure 10 [images/Ika/notes8.tga] |
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Figure 11 [images/Ika/notes10b.tga] |
The head and the neck are limb-children of the last limb in the spine. The neck should be left in FK mode, while the head may be left in either FK or IK mode depending on how you intend to animate it.
An easier method is to use a three-segment chain (Fig. 12). This allows the skin to fold properly at the joint, without suffering from severe "drinking straw" pinching artifacts.
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Figure 12 [images/Ika/notes2.tga] |
The IKAs should be added from the top view so that the hinge allows the arms to bend forwards (Fig. 13). Try holding out your own arm in a similar position and watch how it bends. The arms should be limb-children of the last limb in the spine.
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Figure 13 [images/Ika/notes13.tga] |
Legs can be modeled using a three-segment chain similar to the arm chain. The legs should be limb-children of the first limb in the spine (Fig. 14).
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Figure 14 [images/Ika/notes14.tga] |
Note that the two bones have been left in FK mode to make them easier to control.
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Figure 15 [images/Ika/notes12.tga] |
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Figure 16 [images/Ika/notes4.tga] |
Hand and foot empties are used as effector parents to guide the arm and leg chains (Fig. 17).
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Figure 17 [images/Ika/notes16.tga] |
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Figure 18 [images/Ika/notes9.tga] |
Deformation objects are limb-parented to IKAs in the primary frame and are left in FK mode (Fig. 19).
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Figure 19 [images/Ika/image3.tga] |
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Before your IKAs can smoothly deform your meshes, you must collect IKAs together and build them into a skeleton.
Press CTRL+K to calculate the skeleton. Note that the highlighted bone (the bright pink one) will be the one that contains the skeleton information (Fig 20).IKAs can be used in multiple skeletons at the same time.
To apply a skeleton to a mesh, make the root IKA the parent of the mesh and select the USE SKELETON option when prompted.
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Figure 20 [images/Ika/notes17.tga] |
You can adjust the deformation radius of the skeleton elements by adjusting the Deform Max Dist and Deform Weight entries in the root bone's edit menu accessed with F9 (Fig. 21). The Max Dist is measured in grid units and refers to the diameter of the effect (rather than the radius).
Any skeleton object that has a Deform Max Dist of 0 will affect the entire mesh. This is usually not desirable, so each item in the skeleton should have a distance specified.
Avoid setting the deformation distances too high or limbs may affect vertices that they normally shouldn't be able to reach. It is better to set the distance too low and to compensate with extra deformation objects.
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Figure 21 [images/Ika/notes11.tga] |
The deformation zone surrounding each IKA or Empty in a skeleton is an elliptical shape (Fig. 22). This radius can be non-uniformly scaled by scaling the object, or by adjusting the Deform Max Dist settings in the skeleton's EditWindow.
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Figure 22 [images/Ika/notes15.tga] |
![]() It is not necessary to recalculate the skeleton after making changes to the Deform Max Dist or Deform Weight entries in a skeleton although you may not see the changes until the frame changes. |
Before deleting a bone, or if you wish to remove one from a skeleton, you must select all of the skeleton's IKAs except for the one you wish to remove, and recalculate the skeleton. Fig. 23 shows the spinal chain being removed. If you simply delete a bone, the skeleton's deformation weight and distance settings will be lost and you will have to manually enter them again.
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Figure 23 [images/Ika/notes18.tga] |
If you change the rest position of any of the existing bones, be sure to recalculate the skeleton. Note that when the skeleton is recalculated, any meshes that use the skeleton as a parent will reset to their rest positions. Make sure you only recalculate the skeleton when it is in its rest position, or else you will find that the skeleton and the mesh are no longer in sync with each other.
Depending on your character's design, it may make sense to calculate more than one skeleton. For example, the lower body and feet could use a different skeleton than the upper body. Since Blender normally only allows a single parent per object however, you must have designed your character so that the upper and lower body are separate objects.
Fig. 24 shows the two skeletons, represented by different colors. The ROOT bone contains the deformation information for the lower half of the body, while the spinal chain contains the information for the upper half.
The advantage to this method is that you can isolate deformations to specific parts of the body: moving the legs will not cause bending in any part of the upper body.
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Figure 24 [images/Ika/notes19.tga] |
You can control most of the character's limbs by simply moving the control empties and setting LOC keys for them with IKEY >>LOC. This is easiest if you hide all layers except for the ones containing the control empties and the IKA skeleton.
Certain controls such as the Shoulder Roll empties may require ROT keys instead of LOC keys. The Pelvis and the ROOT will require both LOC and ROT keys.Setting LOC and ROT keys for the Pelvis empty allows you to add bounce to the character's movements, as well as twisting the torso relative to the placement of the feet. The Spine Target empty controls the amount of bend in the body itself.
IKAs that have been left in FK mode (such as the head and feet) may be manipulated directly. Usually you will only need to set ROT keyframes for these limbs.
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Figure 25 (DTP: Please use the chart.ai !) [images/Ika/chart.tga] |
You can take a look at the final knight model with skeleton in the file KNIGHT_IKA.BLEND on the CD-ROM (fig. 26).
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Figure [images/Ika/final.tga] |