Controlling the Stride

When you're working with biped actors, you can control the length of their stride when they are walking at very slow speeds in the simulation, such as if they are walking up a hill or slowing down to avoid other actors.

When you walk slowly, your stride is shorter and you don't lift your feet off the ground very much. If you don't adjust a regular walk cycle when the actors are moving at a slow speed, it may appear as if they're walking in slow motion or through water.

In the image below, the actors are walking with their normal stride length.

In the image below, the actors are walking with a shortened stride when they walk slowly as they start to go up a hill.

Controlling the stride involves setting the stride length to be used only when the actor is walking slowly, as well as the speed at which this short stride is used. Then you constrain the legs and set the actor's foot height to be used for the slow stride.

1. Make sure that the deformers are parented correctly in the rig proxy for constraining the legs - see Modifying the Actor's Rig.

2. In the simulation point cloud's Emit ICE tree, select the Enable Stride Control option in the Initialize Locomotion Data compound.

3. Set the Min Walk Stride Scale and Max Stride Speed values in this compound. You usually want to make the scale of the actor's stride smaller that the usual walking stride (such as half its length) when the actor is walking at a slow speed. The stride length is scaled only when the actor moves at or slower than the Max Stride Speed value.

4. In the simulation point cloud's Skeleton Simulation ICE tree, get a Crowd Stride Control compound and plug it into an ICETree port below Set Locomotion.

   Note

   You can also use this compound in another ICE tree in the Simulation region and put it above the tree that contains Set Locomotion.

5. Open the Crowd Stride Control compound's property editor and specify the rig proxy deformers to use for the Left and Right legs as described in Constraining the Legs to the Ground.

6. Set the Root Direction and Knee Direction to the deformer's local axis that is pointing toward its children, as described in Constraining the Legs to the Ground.

7. Set the amount that the foot is lifted at slow speeds with the Height Min and Height Scaling values.

   When an actor walks slowly, the feet don't usually lift much off the ground, so you usually want to scale down the height of the foot with the Height Scaling value, such as to half the height.

   The minimum height (Height Min value) should be set to the height of the foot in the rig proxy in its resting position. This prevents the foot from going lower than this value when you adjust the Height Scaling.