API Reference — `dna/layers/TwistSwingBehaviorWriter`

`class TwistSwingBehaviorWriter : public virtual DefinitionWriter`

Write-only accessors to the swing and twist data associated with a rig — defining twist/swing parameter groups, their axis, driver control indices, driven joints, and blend weights.

When to use this

Use this when authoring or editing twist/swing rigging: setting up which joint rotation drives a twist chain, which joints it outputs to, and how the effect is blended across them. Implementors should inherit from Writer itself, not this class directly.

Method groups

Group	Methods
Twist	clearTwists, deleteTwist, setTwistSetupTwistAxis, setTwistInputControlIndices, setTwistOutputJointIndices, setTwistBlendWeights
Swing	clearSwings, deleteSwing, setSwingSetupTwistAxis, setSwingInputControlIndices, setSwingOutputJointIndices, setSwingBlendWeights

Example

// writer implements Writer, which composes TwistSwingBehaviorWriter
writer->setTwistSetupTwistAxis(0u, dna::TwistAxis::X);
const std::uint16_t controlIndices[] = {0u, 1u, 2u, 3u}; // quaternion x,y,z,w
writer->setTwistInputControlIndices(0u, controlIndices, 4u);
const std::uint16_t jointIndices[] = {10u, 11u};
writer->setTwistOutputJointIndices(0u, jointIndices, 2u);
const float blendWeights[] = {1.0f, 0.5f};
writer->setTwistBlendWeights(0u, blendWeights, 2u);

Parameters

Name	Type	Description
`twistIndex`	`std::uint16_t`	required — position of the twist parameter group; storage resizes implicitly to fit.
`twistAxis`	`TwistAxis`	required — the twist axis of the parameter group.
`controlIndices`	`const std::uint16_t*`	required — pointer to raw control indices representing the driver joint rotation; always 4 values (quaternion x,y,z,w).
`controlIndexCount`	`std::uint16_t`	required — number of raw control indices to copy.
`jointIndices`	`const std::uint16_t*`	required — pointer to joint indices of the twist-driven joints.
`jointIndexCount`	`std::uint16_t`	required — number of joint indices to copy.
`blendWeights`	`const float*`	required — source address of twist blend weights to copy; one weight per output joint.
`blendWeightCount`	`std::uint16_t`	required — number of blend weights to copy.

Watch out for

deleteTwist removes a specific parameter group by index — distinct from clearTwists, which removes all of them.
Parameter group storage is implicitly resized to fit whatever index is written to, so groups can be set out of order.
Inherit from Writer, not directly from TwistSwingBehaviorWriter. Direct inheritance violates the intended interface hierarchy.
Passing controlIndexCount != 4 for quaternion input methods may produce undefined results — the driver joint rotation is always encoded as a single quaternion.

Constraints

Blend weight arrays must contain one entry per output joint in the corresponding joint index array.

API Reference — dna/layers/TwistSwingBehaviorWriter

class TwistSwingBehaviorWriter : public virtual DefinitionWriter