The Problem

You've created a nice little character animation scene. You modeled the object, created the skeleton, tweaked the bones, set up the IK relationships, brushed up on your Muybridge, and created keyframes. Everything looks great, so you render out an animation and...oh no...the feet...the stupid feet...

The feet are going into the floor...sinking just a little bit under the ground plane polygon...

This is why Footlocker exists...

Footlocker

Footlocker solves the nagging problem of 'foot sinkage' through sheer brute force. Basically, it forces all points that are lower than the ground plane up to the ground plane level and it keeps the other points in proportion. If you bear that in mind, the interface is pretty straightforward.

The AXIS determines which direction Footlocker will force the points. Usually this is the Y axis, since the most common use for the plug-in is to stop feet going through a floor - but you could also stop feet from going through a wall, if you really wanted to - just pick another axis.

The BEFORE BONES button determines whether Footlocker effects the object's geometry before bones are applied to it, or after. This is obviously important because bones can have a big effect on an object's geometery, especially in character animation - which is the prime use for Footlocker.

OBJECT GROUND tells Footlocker where the bottom of the object is. This should be the bottom of the object as created in Modeler, not what may look like the bottom of the object in Layout. Let's look at an example...

	This robot scene that included with LightWave looks like a prime candidate for Footlocking...but just loading the scene and applying Footlocker without understanding the settings will lead to frustration and crying. Why? Because the robot foot's Object Ground is not 0.
	This becomes obvious when the object is un-parented and it's position and rotation are reset. The object's real ground is somewhere under the 0 point of the Y axis. Loading the object in Modeler will give you the exact position of the bottom points.

The DIRECTION button gives you three choices - Positive, Negative, or Falloff. Most of the time, you'll want Positive or Falloff selected. The Negative option turns the plug in into 'Ceilinglocker' - it forces points that are higher than the ground plane down below the world ground - just make sure your Object Ground number represents the topof the object.

Selecting Falloff gives your object some flex, and turns on the MAX STRENGTH and MIN STRENGTH buttons. It's especially useful for single-mesh objects, where all you really want to do is stop the feet from going through the floor and you feel confident enough in your abilities as an animator to keep the torso and head above the ground plane. When you use Falloff, thes numbers represent the range of effective values - A Max Strength of 0 and Min Strength of 1 means that the object bottom is at 0, and any points in the object that are above 1 units won't be effected. The points in between 0 and 1 will be effected, with their strength ramped. You can also make Falloff create a Negative effect, complete with falloff - simply make the Min Strength a larger number than the Max Strength.

Finally, the WORLD GROUND determines exactly where the Ground Plane is at. You creative types may want to use something other than 0, after all.

Using VARIABLE world ground lets you define the ground plane by a movable object that you define - typically a null object. You define the object by entering it's name (or the first few letters, if they are unique) in the PREFIX selector. Be warned - this is case sensative, so spelling and capitilazation count. The Variable ground option creates a 1 meter 'force field' around the object whose prefix you've specified. You can resize the object to have it effect a larger area than one meter. Then, just move the ground null around under your FootLockered object and you can avoid foot sinkage anywhere in your virtual world. If you want to visualize the Variable Ground object, just create a one meter disk and use that as your object, remembering to turn off all rendering options.