In order to correctly drive corrective shape keys from a freely
rotating organic joint it is very often found necessary to
decompose the rotation into separate bending and twisting
motions. This type of decomposition cannot be reproduced by
any Euler order or a single quaternion.
Instead this is done by using a helper bone with a Damped Track
constraint aimed at the tail of the control to pick up the bending,
and its helper child with Copy Transforms to separate the twist.
Requiring two additional bones to drive a shape key or a correction
bone seems inconvenient, so this implements the necessary math as new
options in the recently introduced Rotation Mode dropdown of the
Transform Channel driver variable type. The data is also accessible
as a Transformation constraint input.
The output is in the form of Quaternion-derived 'pseudo-angles',
which for `Swing and Y Twist` would represent the following:
* W: true bend angle, independent of bend direction.
* Y: true twist angle.
* X, Z: pseudo-angles representing the proportion of bending around X/Z.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D5651
When there was no rotation the axis was zerod,
while not exactly a bug, it means changing the angle does nothing
and all axis-angle values are initialized with Y=1,
use this convention when resetting the axis too.
BF-admins agree to remove header information that isn't useful,
to reduce noise.
- BEGIN/END license blocks
Developers should add non license comments as separate comment blocks.
No need for separator text.
- Contributors
This is often invalid, outdated or misleading
especially when splitting files.
It's more useful to git-blame to find out who has developed the code.
See P901 for script to perform these edits.
The main use one can imagine for this is adding tweak controls to
parts of a model that are already deformed by multiple other major
bones. It is natural to expect such locations to deform as if the
tweaks aren't there by default; however currently there is no easy
way to make a bone follow multiple other bones.
This adds a new constraint that implements the math behind the Armature
modifier, with support for explicit weights, bone envelopes, and dual
quaternion blending. It can also access bones from multiple armatures
at the same time (mainly because it's easier to code it that way.)
This also fixes dquat_to_mat4, which wasn't used anywhere before.
Differential Revision: https://developer.blender.org/D3664
- Remove 'rotate_m2', unlike 'rotate_m4' it created a new matrix
duplicating 'angle_to_mat2' - now used instead.
(better avoid matching functions having different behavior).
- Add 'axis_angle_to_mat4_single',
convenience wrapper for 'axis_angle_to_mat3_single'.
- Replace 'unit_m4(), rotate_m4()' with a single call to 'axis_angle_to_mat4_single'.
Added conversion to and from exponential map representation. This
representation is useful for interpolation of > 2 quaternions, or in
PD controllers.
Implementation in C functions quat_to_expmap,
quat_normalized_to_expmap, and expmap_to_quat with Python API, unit
tests and documentation.
Added Quaternion.to_exponential_map() and Quaternion(3-vector) to
Python API.
Reviewers: campbellbarton
Projects: #bf_blender
Differential Revision: https://developer.blender.org/D1049
Basically, `angle_compat_rad()` was completely broken -
example of result it could produce:
| new angle | compat angle | result
| -0.000000 | 3.141593 | -> 3.141593
... Where 0.0 (or 2 * PI) would be expected!
