// From root to end-effector
public void DoBackwardPass()
{
Vector2 targetCenter = lastTargetCenter;
for (int boneIdx = bones.Count - 1; boneIdx >= 0; --boneIdx)
{
Vector2 currentEnd = positions[boneIdx];
Vector2 currentCenter = positions[boneIdx + 1];
float targetRotationDelta = Vector2Utils.AngleBetween(
currentEnd - currentCenter,
currentEnd - targetCenter);
float unconstrainedTargetRotation = rotations[boneIdx] + targetRotationDelta;
float targetRotation = ConstraintRotationAgainstParent(boneIdx, unconstrainedTargetRotation);
Vector2 targetEnd = targetCenter + Vector2Utils.RotateBy(targetRotation, unposedBoneVectors[boneIdx]);
positions[boneIdx + 1] = targetCenter;
rotations[boneIdx] = targetRotation;
targetCenter = targetEnd;
}
positions[0] = targetCenter;
}
//From end-effector to root
public void DoForwardPass()
{
Vector2 targetEnd = firstTargetEnd;
for (int boneIdx = 0; boneIdx < bones.Count; ++boneIdx)
{
Vector2 currentEnd = positions[boneIdx];
Vector2 currentCenter = positions[boneIdx + 1];
float targetRotationDelta = Vector2Utils.AngleBetween(
currentEnd - currentCenter,
targetEnd - currentCenter);
float unconstrainedTargetRotation = rotations[boneIdx] + targetRotationDelta;
float targetRotation = ConstrainRotationAgainstChild(boneIdx, unconstrainedTargetRotation);
Vector2 targetCenter = targetEnd - Vector2Utils.RotateBy(targetRotation, unposedBoneVectors[boneIdx]);
positions[boneIdx] = targetEnd;
rotations[boneIdx] = targetRotation;
targetEnd = targetCenter;
}
positions[bones.Count] = targetEnd;
}