[Bf-animsys] Visualisation Matters

[Joshua Leung]

Hi all,

Once again, it's that time of the year when I start looking into doing
another incremental round of improvements on the visualisation features -
i.e. ghosting and paths in particular.

At the time of writing, there are two big "holy grails" that would be nice
to have:
1) ghosting of the actual meshes deformed by the armatures, and
2) editing of the path verts


Below are some notes on how these could possibly be implemented. Comments on
the suitability of these methods, or even proposals for better systems are
welcome.

---------------------------------
1) Ghosting meshes:
A rather crude approach to this would be to simply draw the mesh posed by
the armature in different ways at several different frames, if a given mesh
has an armature parent (and an armature modifier). This would not work for
normal animated objects, and would be really slow.

However, the approach I'm currently thinking of would require about 3 parts:
a. Pointcache modifier - used for baking armature,etc. deforms on points to
cached data. The advantage here is that if done right, we could look forward
to some improved playback speeds in some cases. It would also make some
effects (such as 'smear' visualisation - see Pigeon Impossible Blog for
details) possible, since those effects depend on stuff like this.

b. Ghost/Motionblur instancer modifier - this modifier uses the pointcache
(a), to get the mesh data at another frame and draw it as part of the mesh
(probably with different material settings?). It would be able to therefore
be used for both armature and object-level animation, and could be used to
give more control over what gets ghosted by making the user explicitly
define what to ghost. Probably a pointcache from another object could even
be used in some cases? Maybe for motionblur during rendering, this modifier
could also act as a more 'in camera' approach to motionblur rendering?
(chances are, renderers wouldn't cope with having predefined meshes
specially for motionblur being created, as they'd treat the meshes as extra
data)

c. Improved decimator - I'm aware that Genscher was working on something
along these lines? Basically, this is only an optional part of the setup,
but could potentially be hooked up with the ghost-modifier to decrease the
complexity of the mesh over time. Of course, this may not be practical as it
is likely to be too slow to be useful, clumsy to setup, and/or cause
problems with the overall shape of the mesh which may not be desired.

-------------------------------
2) Editing Paths:
There are two big obstacles here: figuring out how to map path edits to
transforms (rotations vs scaling vs location), and how to allow the user to
start editing the path vertices.

The first issue is relatively trivial, and is really just a matter of
further investigation I guess.

However, I need some suggestions for the second problem. As I currently see
it, most people would prefer to be able to just click on some path vertex
and then move it by simply dragging, all without having to go into any
special sub-modes or so. There are several disdvantages of this, namely that
it practically violates many of the established expectations of how users
usually expect to be able to interact with elements with editable vertices
in Blender (selection + transform tools are limited). Also, this would
complicate pose-mode event handling in particular, since we'd have to deal
with priority of bones vs curve verts too...

However, if we went with the "separate mode" approach, it becomes a bit more
frustrating to try and edit the paths of a few bones, especially if you
wanted to edit the paths of different bones but didn't want to have to stop
and think which ones you'd like to isolate for editing. Just clarifying that
a bit, I'm thinking that with this separate mode, you'd select one or more
bones with some paths, enter the mode, and only be able to tweak the path
vertices of the bones selected when entering the mode. Then, when those
paths were tweaked ok, you could exit the mode, and continue editing other
parts. This might be an acceptable compromise, given that when editing a
path, I'm assuming that you're going to only concentrate on the motion of a
few limbs/controls at a time.

-----------------------------------

</end long mail>

Regards
Aligorith
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