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Grounder

Grounder is an automatic vertical foot placement and alignment correction system.

How does it work?

The solver works on a very basic principle: The characters are animated on planar ground. The height and rotation of the feet, as they are animated, should only be offset by the difference of ground height at their ingame positions from the root height.

Let's sample a frame in the animation, where the character's left foot y position is 0.1. Ingame, the Grounding solver will make some raycasting to find the real ground height at the left foot's position. Let's say that the raycasting returns 0.2. If the character's ingame y position is 0, the ground height at the foot's position relative to the character root is 0.2. The foot must be vertically offset by that exact value, ending up at 0.3.

This approach guarantees minimal interference with the animation, because the feet will only be offset when the ground height at their positions differ from the character root's height. If that offset is negative, meaning ground height at the foot position is lower, then the solver needs to pull down the character from the pelvis so that the feet could reach their offset targets.

GrounderHowItWorks.png

Getting started:

Solver variables:


Grounder Components

GrounderFBBIK

GrounderFBBIK uses the FullBodyBipedIK component for offsetting the feet and optionally bending the spine. This is most useful if your character already has some FBBIK functionality and you need the component anyway. GrounderFBBIK uses the positionOffset of the effectors so you can still pin the feet without a problem if necessary.

Component variables:

GrounderFBBIKComponent.png

GrounderBipedIK

GrounderBipedIK uses the BipedIK component for offsetting the feet and optionally bending the spine. With BipedIK you will not have to manually set up the IK components for the limbs.

Component variables:

GrounderBipedIKComponent.png

GrounderIK

GrounderIK can use any number and combination of CCD, FABRIK, LimbIK, or TrigonometricIK components for offsetting the limbs. This is most useful for spider/bot types of characters that have more than 2 legs connected to a single hub.

Component variables:

GrounderIKComponent.png

GrounderQuadruped

GrounderQuadruped uses 2 Grounding solvers. That means 2 hubs that can have any number of legs.

Component variables:

GrounderQuadrupedComponent.png