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BonedSuspension        

BonedSuspension

General bone stuff

Each bone consists of a position, an orientation, and a parent. The root bone is by conventional called 'chassis'. The position of the bone is usually denoted in the modeller by the 'head' or 'start' of the bone graphic. The orientation of the bone is usually illustrated with +y being the direction the bone graphic is 'pointing', and also the 'roll' quantity.

Suspension bone rigging

The chassis bone should be at 0,0,0 and oriented with the identity orientation (i.e. +y (the bone graphic) should point in the +y direction of the parent, which in this case is object space +y).

Hierarchy:
chassis
 - aim_bone
    - steer_bone
       - axle_bone
          - wheel_bone
 - aim_bone
    - steer_bone
       - axle_bone
          - wheel_bone
 - aim_bone
    - steer_bone
       - axle_bone
          - wheel_bone
 - aim_bone
    - steer_bone
       - axle_bone
          - wheel_bone

Either the aim bone or steer bone can be omitted (but not both).

The only reason to have both aim bone and steer bone is if the aim bone is controlled independently to the steer, e.g. for retracting aeroplane landing gear. In this case, the aim bone is rotated depending on whether the gear is retracted. The steer bone is rotated due to steer in the usual way.

A wheel without steer bone cannot be steered.

A wheel without aim bone will aim the suspenion ray from the steer bone.

The aim bone should be at the place where the ray is shot, and pointing in the direction the ray should be shot.

The steer bone should be at the same location as the aim bone and should define the axis around which the wheel will be steered.

The axle bone should be positioned in the location where the centre of the wheel will be during maximum compression of the spring. It should have no orientation.

The wheel bone should be positioned in the location where the centre of the wheel will be during minimum compression of the spring. It should be oriented so that +y is pointing towards the right side of the car, and that the y axis is the axis around which the wheel will rotate due to engine torque.

Dynamic updates

The axle bone has its y position offset by the extension of the spring (always
a negative number if the vehicle is on the ground, i.e. the spring is always
under compression)

The steer bone is rotated about y by the required amount when the wheel is
being steered to one side or the other.

The wheel bone is rotated about -y by the amount the wheel has spun around.

Category:Vehicle?