Ok. Thanks for the explanation. That shift thing is very unintuitive. Hopefully you will get rid of that in favor of something that can be changed any time by dragging a handle or changing a "thickness" setting in the toolbar.
More generally I guess I still don't get why you'd want to have a 3D box tool. It's basically an extrusion tool that happens to only extrude rectangles. Why not make something that's capable of extruding anything and applying a perspective transform to it? Like the question that was on the list earlier today -- about extruding fonts. This would be a useful tool for doing that, if it weren't restricted to extruding only rectangles.
--bb
On 7/5/07, Maximilian Albert <Anhalter42@...173...> wrote:
Hi Bill,
> What am I missing here? I just updated SVN, uncommented the line to show
> the 3D box tool and rebuilt.
If it's too unconvenient to manually uncomment the line you can just
press X or Shift-F4 to activate the tool (although then the icon in the
toolbox won't be visible, of course).
> But I can't seem to figure out how to get the tool to do anything other
> than draw an axis aligned rectangle.
Check out
http://www.rzuser.uni-heidelberg.de/~malbert/core_functionality.shtml
for a description of the envisaged behaviour of the tool (paragraph #1
explains how to create a box). Note that each 3D box is associated with
a certain 'perspective', which is given by the positions/directions of
the three vanishing points (VPs) together with their respective states
(which in turn can be 'infinite' or 'finite', meaning that perspective
lines in the direction of the VPs are either parallel or meet in the VP).
Currently VPs are not draggable yet, thus an initial fixed perspective
is created in box3d-context.cpp, lines 120-132. For each VP both a
location on the canvas and a direction is specified. These determine the
behaviour of perspective lines towards this VP for each of the states
'finite'/'infinite'.
Notice that the directions specified in
box3d-context.cpp for the VPs in
X- and Y-direction are 'left' and 'up', respectively, and that their
states are both VP_INFINITE. That's why opposite sides of the rectangle
you create are parallel (
i.e. don't meet in a finite VP) and
axis-aligned. You can play with different directions or initial states
for the VPs to observe the effect this has (unfortunately, this needs
recompiling because the perspective is hard-coded at the moment).
Now the axis aligned rectangle you see only represents one face of the
box. To extrude the box and make it appear 3D, press Shift once the
front face is created (but keep holding the mouse button). This fixes
the front face and starts dragging the remaining faces in Z direction.
As I said, the initial states of all three VPs are 'infinite'. But when
you activate the 3D box tool you will observe three small unfilled
squares on the canvas. These indicate the positions of the VPs if their
state would be 'finite'. Although at the current stage VPs are not
draggable, it is possible to toggle their states by pressing the buttons
in the 3D box toolbar (they are rather easy to overlook; each one simply
shows two parallel lines, but the tooltips should be more meaningful).
When the state is toggled to 'finite', the square representing the VP is
color-filled and corresponding edges of newly created boxes are now
drawn along perspective lines meeting in that VP. Toggling it back to
'infinite' unfills the square and draws edges parallel again. I know
that it's rather unintuitive to have the squares for the VPs shown on
the canvas but boxes ignore them when they are white. But since the
VP-machinery needs to be rewritten anyway (very soon hopefully), I
didn't want to invest a lot of time to make static VPs work more
beautifully.
I hope this makes things a bit clearer. Don't hesitate to ask if
something still remains cryptic. And your feedback is very welcome.
Best regards,
Max