A very cheap IK hip

2011-02-05T22:14:00.001-08:00

This is an example of a super cheap rig for the need of keeping the spine FK-based, but controlling the hip without moving the entire upper body.

1. Say I have such a set of character skeleton.

2. And I have such a set of controllers.
The pinks are the FK controls for the spine,
the yellow square is for the hip(IK),
and the big blue circle is the COG.
The hierarchy of the pinks are:
the lowest circle -> the middle circle -> the top circle.

3. Now put an IK (SC solver without sticky on) from the bottom spine joint to the one above, while the IK handle is still selected, parent it to the bottom pink circle. (shift select the pink and hit "p")

4. do the same to the second joint on the spine:
put IK on, and parent it to the pink circle below it (the middle pink circle).

5. do the same to the top one, put IK on, and then parent it to the pink circle below it.

6. make the yellow square point constrain the bottom spine joint. (the square controls the joint)

7. We are almost done! Just make sure your IK legs and feet are set, and the leg roots (the ones close to the hip) parent-constrained (or parented) by the yellow square.

Now you got your hip control (the yellow square), you can move the hip without moving the shoulder or the chest. You can also rotate the hip, make it dance.

And you can still manipulate your spine FKwise.

8. Finally, put all the necessary stuff into the COG (the big blue circle), in this case they include the yellow square and the bottom pink circle. (That's it...) And this is what a COG is doing: COG controls the entire upper body, and hip control does the hip alone, and you got the FK spine.

The making of the Paint Trail

2010-09-12T14:40:00.000-07:00

Part A. Trail Rig:

1. Create the trail Geo with 20 segments on a polygon.

2. Put 21 joints on both sides, hirarchy from top to bottom. Name them accordingly.

3. Weight the Geo to both joint groups. (select those 2 joint group roots and then select the geo, smooth bind)

4. Create CV curves for both joint groups, with 5 CVs respectively snapped on the 1st, 6th, 11th, 16th, 21th joints.

5. Select the first joint and the last joint, then select the curve, create Spline IK with "auto create curve" UNCHECKED, do it for both sides.

6. create a cluster for each CV, in total 10 clusters on both sides (select CV, create deformers -> cluster)

7. create 10 locators and snap them on all 10 clusters respectively. Name them accordingly.

8. Select the locator then the cluster at the same location, hit Point Constraint with "offset" unchecked.

9. You might have found that this rig has to be strechy and squashy, people would do it differently since there are so many ways to achieve it. The way I did is create curveInfo node on the spline curve, then set expressions to make all the joints scaled on Z according to the times the spline curve length is modified.

Part B. Trail Texture:

- This is the ramp1.

- conect fractal1 to the gray part on ramp2.

- conect ramp2.outColorR to blendColors1.blender

- conect ramp1 to blendColors1.color2

- blendColors1.color1 has to be white.

- conect blendColors1.outColorR to lambert2.transparencyR, do the same to G and B channels

- the Ambient Color on lambert2 has to be white.

- the Color on lambert2 can be any color you like to see on the Trail.

Part C. Animation:

- before getting into this part, save the trail file as a reference, then import to the scene with the animated paint roller.

1. go to the first frame of the scene, create 2 locators and snap them at the points that look generating the Trail. Name them properly.

2. point-constrain all locators in each row to either locator on the roller-head. Do the same to the other side.

3. bake the animations of all channels on all locators of the Trail.

4. offset the keys of those locators 1 frame after the previous ones, so all 5 keys on each side will be at the 1st, 2nd, 3rd, 4th, 5th frame respectively. As a result, the Trail Geo will track in the same way.

CC's Pocket

A very cheap IK hip

The making of the Paint Trail