[tuhopuu-devel] Constraints UI

[Matt Ebb]

Hi there,

I'm sending this out first rather than just going ahead and doing it because
I wanted to check with contraint guru theeth that it wouldn't break
anything, and see if there are any problems I may have overlooked.

I think the UI/workflow for adding constraints is backwards and I want to
fix it. It's nothing complex, but last week after going through the
frustration of rigging a character and adding 30 action constraints to just
finger bones I realised it could be improved.

Rather than 'adding a constraint', getting a default of Track To, then
changing it to what you want, you should be able to choose the constraint at
the time of adding it. Reasoning: Users don't want to 'add some abstract
notion called a constraint', they want their objects to track others, or to
follow paths or whatever. Imagine if when you added a 3D object you had to
do 'add object' then go change it to a mesh, camera, lamp, whatever, in a
menu somewhere.. yuck. It's also nice to be able to see all the choices
there before you add it. A bit more explorable.

Also for efficiency reasons - to add action constraints to my fingers, I had
to click on add - move mouse to the menu on the constraint - click, drag to
change from Track To to Action. I should have just clicked on add
constraint - drag across a menu - release mouse on 'Action'. It's also much
more understandable when the constraints seem more concrete: "this is my
copy location", rather than "this is a variable thing that can change
between all sorts of tangentially related functions".

The idea of having these amorphous abstract constraints that can be changed
from one type to another is silly anyway since between themselves, the
constraints are functionally very different. How many people add a
constraint to make their object copy another's location, then later on
change their mind and realise "no, actually I want this object to be an IK
solver for a chain!"...? Not many. Besides, when you change a constraint
type, none of the settings persist anyway.

So my proposal:
* Change the add_new_constraint function in editconstraint.c to accept an
argument describing the constraint type, for example int constraint_type or
whatever it needs to be.
* Change the line con->type = CONSTRAINT_TYPE_TRACKTO;
to con->type = constraint_type;
* Change the 'Add' button into 'Add Constraint' (clearer) and when clicked,
make it fold out a menu with the different constraint types listed. This can
work in a similar way to the pulldown menus, for speed  - click+hold on add
constraint, drag mouse right over the menu, release on the entry you want.
The menu entries will just use add_constraint(*relevant constraint type*) or
whatever is necessary.
* Remove the 'constraint type chooser' menu from the constraint panels, to
simplify, streamline, make the UI more 'concrete'. (If people really do want
to change their constraint type for some obscure reason, it's only one more
click to delete it and add a new one).

I mention this now, because I think it would be nice to go along with the
new constraints when they get ported over to bf.

So, any issues or gotchas I should worry about? Or just get in there and do
it?

Cheers

Matt