General Category > Anim8or v0.98 Discussion Forum
Feature Request Thread
nemyax:
A traditional bone in a 3D package is:
* A transformation
* A link to the parent, if any
* Some visualisation attributes (shape, drawing mode, length, etc.)
* Some constraint-related attributes (FK limits, IK limits, etc.)It's obligatory that at least all of the transforms (translation, rotation and scale) be animatable.
Deepthought:
so: if you scaled a bone, it would move the child bones and scale the vertices?
Steve:
Any change to a bone's transform matrix will affect any vertices that it influences (and of course will move/rotate any child bones). Currently the only thing that you can change is the orientation but if support for scaling, length and location are added then the vertices will move/scale like this:
changing length: vertices near the root will not move much, those near the tip will scale more or less as the bone scales. Any change is in the direction of the bone.
changing scale: vertices scale away from or towards the bone. It's not clear where the center of the scaling should be - the base of the bone, the center?
moving: all vertices move equally.
Does that sound OK?
nemyax:
--- Quote from: Deepthought on January 14, 2016, 01:27:32 pm ---so: if you scaled a bone, it would move the child bones and scale the vertices?
--- End quote ---
It would offset and scale the child bones, unless they are configured not to inherit scale (a common option in animation software).
Raxx:
--- Quote from: Steve on January 14, 2016, 01:49:22 pm ---changing length: vertices near the root will not move much, those near the tip will scale more or less as the bone scales. Any change is in the direction of the bone.
changing scale: vertices scale away from or towards the bone. It's not clear where the center of the scaling should be - the base of the bone, the center?
--- End quote ---
I don't see any point in implementing length animation when there's scaling animation, unless you're just describing what would naturally happen when scaling along the Y axis? As I mentioned in an earlier post, if both length and scale were separate entities, it'd become confusing differentiating between the two when in the workspace.
In Blender, scaling starts from the base of the bone, and the vertices scale at the same rate that the bone does (as if the vertices and bone were in a group with the bone's base as the center of geometry).
Also, as nemyax mentioned, in Blender (and I'm sure most other animation packages) bones have the option to inherit scale, location, and orientation, which can each separately be enabled/disabled. Which means that if scaling a forearm bone, it can become massive, but if the hand bone is set to not inherit scale, it'll remain in its small original state. If set to inherit, it'll scale with the forearm bone. In Blender inheritance is enabled for all three transforms by default.
Also the option to be connected/disconnected, which means that when connected, there's no way to move the bone away from its parent bone (the base is stuck to the parent's head). When disconnected it can be moved away. This option becomes important not just for normal animation, but also later on when constraints are implemented.
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