API Reference — dna/layers/TwistSwingBehaviorReader

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class TwistSwingBehaviorReader : public virtual DefinitionReader

Read the twist and swing deformation parameters for a rig — the per-group axis, driver control indices, output joint indices, and blend weights for both motion types.

When to use this

Use this interface when you need to inspect or serialize the twist/swing behavioral layer of a DNA asset. It pairs with TwistSwingBehaviorWriter for read/write access. Do not implement this interface directly — implementors should subclass Reader instead, as this class is an internal layer in the reader hierarchy.

Method groups

Group	Methods
Twist	getTwistCount, getTwistSetupTwistAxis, getTwistInputControlIndices, getTwistOutputJointIndices, getTwistBlendWeights
Swing	getSwingCount, getSwingSetupTwistAxis, getSwingInputControlIndices, getSwingOutputJointIndices, getSwingBlendWeights

Example

// Iterate all twist groups and read their driver quaternion control indices
const uint16_t twistCount = reader->getTwistCount();
for (uint16_t i = 0u; i < twistCount; ++i) {
    TwistAxis axis = reader->getTwistSetupTwistAxis(i);
    // Always exactly 4 elements: quaternion [x, y, z, w]
    auto driverIndices = reader->getTwistInputControlIndices(i);
    auto outputJoints  = reader->getTwistOutputJointIndices(i);
    auto weights       = reader->getTwistBlendWeights(i);
}

// Iterate all swing groups symmetrically
const uint16_t swingCount = reader->getSwingCount();
for (uint16_t i = 0u; i < swingCount; ++i) {
    TwistAxis axis = reader->getSwingSetupTwistAxis(i);
    auto driverIndices = reader->getSwingInputControlIndices(i);
    auto outputJoints  = reader->getSwingOutputJointIndices(i);
    auto weights       = reader->getSwingBlendWeights(i);
}

Returns

ConstArrayView<T> — a non-owning view over the underlying data. Do not store the view beyond the lifetime of the reader object.

Watch out for

• All index parameters (twistIndex, swingIndex) must be strictly less than the value returned by getTwistCount() or getSwingCount() respectively. Passing an out-of-range index is undefined behavior — validate with the count getter before each call.
• getTwistInputControlIndices and getSwingInputControlIndices always return exactly 4 indices representing a single quaternion [x, y, z, w]. Do not treat the view length as variable.
• Do not subclass TwistSwingBehaviorReader directly. Implementors must subclass Reader; this class is an intermediate layer in the interface hierarchy.