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This directory contains a demonstration of DX User
Interactors. The demo allows you to interactively manipulate objects
in the scene independently, and to interactively place and enter
captions into the image.
First copy this directory to someplace where you can write to.
To run the demo, you must first create the run-time loadable
interactor file. This is done by first going to the interactor
subdirectory and typing:
make -f Makefile_arch interactors
where arch is one of ibm6000, sgi, alphax, hp700 and solaris.
(See the note at the bottom of this file for sun4 and aviion)
Once the interactors file has been created,
you can return to this directory and execute the 'demo' script that
you'll find here. Run 'demo', open the control panel and put it in
execute-on-change mode.
Initially, the image contains three colored fragments which are stacked
together in the center of the image. (These are in fact fragments of a
pre-Columbian temple ceiling from Peru; hence the name). Using the
right mouse button, pick one of the colored fragments. This causes
the fragment to be highlighted, and for the system to enter 'slide' mode,
which is interaction mode 0. In this mode you can use the left mouse
button, to slide the selected fragment around. When a vertical stroke
is made with the middle mouse betton depressed, the selected fragment is
rotated. Horizontal strokes with the middle button depressed causes
the image to be zoomed in and out. At any time you can select another
fragment by selecting it with the right mouse button, causing the
previously hightlighted fragment to return to its original color and the
newly selected fragment to be highlighted. Now left and middle mouse
button actions will affect this fragment.
If you use the right button to pick on the background, rather than on
one of the fragments, you enter 'caption' mode. Once you have done so,
you can create a caption by simply typing into the window. Moving the
mouse with the left button pressed will slide the caption around.
Selecting a new point on the background will create a new caption. Once
you have created a caption, you can select it by picking it with the
right mouse button; it then can be manipulated by dragging it with the
left mouse button and by typing characters.
The data structure being manipulated in this application consists of
a DX Group object containing named objects of two types: transformed
objects, which may be any DX hierarchichal structure with a transformation
node at the root, and DX captions. Each of these objects has its object
type attached to it as a string attribute, either "transformed object"
or "caption". An initial state is passed into SuperviseState (which
in the demo consists of a group of three transformed objects, "fragment0",
"fragment1" and "fragment2", each a colored set of triangles with an
identity transform. In addition, the initial camera state is also
passed into SuperviseState, having been created by AutoCamera.
In SuperviseWindow applications, SuperviseWindow itself creates the
window in which the rendered images are displayed, and receive events
that occur in the window (as of today, left, middle and right button
events and keypress events are handled). These, along with the current
size of the window, are passed from SuperviseWindow to SuperviseState,
which uses this information to modify the current state of the scene
objects and camera, which are then passed on to Display to render.
Events that are not actually used by the current interactor are passed
out of SuperviseState and can be interpreted elsewhere in the network.
Under the covers, this works slightly differently in hardware mode.
When hardware rendering is used, events which are requested by the
current interactor are captured by the hardware renderer itself,
which manages the modification of the state as long as a button is
pressed. Other events that are not requested by the interactor are
passed up to SuperviseWindow, and then out into the network. The result
is the same, however; the camera and object that are produced by
SuperviseState on given execution reflect all the events that have
been seen since the prior execution.
In this application, neither of the interactors requests the right
button events; therefore, these events can be interpreted by the
network. Specifically, this application uses these events for picking.
Picking is used both to select an object in the scene for interaction
and to select an interaction mode, by examining the 'object type'
attribute of the selected group member and choosing the appropriate
interaction mode. (If the pick fails to select an object, the
network selects 'caption' mode). Note that since the interaction mode
is an input to SuperviseState, the interaction mode determination must
occur prior to SuperviseState. For this reason, rather than rely on
SuperviseState to excise the right-button events (recall that since
they are not requested by either of the interactors they will pass
through SuperviseState) we must explicitly extract them from the event
output of SuperviseWindow. Similarly, because picking occurs above
SuperviseState, it cannot receive the current state from SuperviseState.
Instead, at the bottom of the 'Window' page of the network you will
see two cases of a simple GetGlobal/SetGlobal that allow the object
and camera state from the previous network execution to be made available
above SuperviseState without an explicit network loop.
Note: Two platforms (sun4 and aviion) do not support runtime
loadable modules. For these, you will need to create a separate
dxexec executable incorporating your custom interactors. For
an example, see samples/supervise/interactors.
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