private void UpdateDerivedValues()
{
// Validate chain. Compute bone lengths, bone indices and total chain length.
if (_isDirty)
{
return;
}
_boneLengths.Clear();
_boneIndices.Clear();
_totalChainLength = -1;
try
{
// Check if chain is valid.
if (!SkeletonPose.IsAncestorOrSelf(RootBoneIndex, TipBoneIndex))
{
throw new ArgumentException("The RootBoneIndex and the TipBoneIndex do not form a valid bone chain.");
}
// Get bone indices.
SkeletonPose.GetChain(RootBoneIndex, TipBoneIndex, _boneIndices);
var numberOfBones = _boneIndices.Count;
// Get bone lengths. We compute the bone lengths from an actual bone pose because
// our archer test model had a scale in the bone transforms. Therefore we cannot
// compute the length from only the bind poses.
_boneLengths.Capacity = numberOfBones;
_totalChainLength = 0;
for (int i = 0; i < numberOfBones - 1; i++)
{
int boneIndex = _boneIndices[i];
int childIndex = _boneIndices[i + 1];
var boneVector = SkeletonPose.GetBonePoseAbsolute(childIndex).Translation - SkeletonPose.GetBonePoseAbsolute(boneIndex).Translation;
float boneLength = boneVector.Length;
_boneLengths.Add(boneLength);
_totalChainLength += boneLength;
}
// Tip bone.
_boneLengths.Add((SkeletonPose.GetBonePoseAbsolute(TipBoneIndex).Scale *TipOffset).Length);
_totalChainLength += _boneLengths[numberOfBones - 1];
// Initialize _bones list with dummy values.
_bones.Clear();
for (int i = 0; i < numberOfBones; i++)
{
_bones.Add(SrtTransform.Identity);
}
_isDirty = true;
}
catch
{
_boneLengths.Clear();
_boneIndices.Clear();
_totalChainLength = 0;
throw;
}
}