Accommodate model operators with "preview"

[vibraphone]

Some model operators (e.g., discrete grow, cgm sweep) can provide useful feedback given an initial set of operator parameters without performing the (normally irreversible) operation. SMTK does not accommodate this yet. The use cases are

• CGM. Methods of GeometryModifyTool that accept a preview argument can provide primitives to be rendered as a result of an operation's preview. This is the majority of solid modeling operators CGM provides.
• Discrete. The grow operator can provide an updated mesh selection given seed points. Perhaps split can as well? Applications must be able to access the preview results in order to allow users to overwrite their seed selection with the returned selection.

[BobObara]

It seems then that operators could have a Pre-viewable attribute indicating that the results can be viewed before the operator is really applied.

Bob

Robert M. O'Bara, MEng.
Assistant Director of Scientific Computing

Kitware Inc.
28 Corporate Drive
Suite 101
Clifton Park, NY 12065

Phone: (518) 881- 4931

On Mar 2, 2015, at 2:49 PM, David Thompson [email protected] wrote:

Some model operators (e.g., discrete grow, cgm sweep) can provide useful feedback given an initial set of operator parameters without performing the (normally irreversible) operation. SMTK does not accommodate this yet. The use cases are

CGM. Methods of GeometryModifyTool that accept a preview argument can provide primitives to be rendered as a result of an operation's preview. This is the majority of solid modeling operators CGM provides.
Discrete. The grow operator can provide an updated mesh selection given seed points. Perhaps split can as well? Applications must be able to access the preview results in order to allow users to overwrite their seed selection with the returned selection.
—
Reply to this email directly or view it on GitHub #98.

[vibraphone]

There are two pieces:

• Providing a chance for an operator to provide a "preview result" (which may be visual like the CGM use case or a mix of visual and non-visual like the discrete grow operator's selection suggestion). Just having a preview method on the base Operator class that returns an attribute would be enough; operators that did not override the method would return an "empty" preview telling the operation to proceed.
• Providing a way for the application to do more than just display preview geometry, but accept user response in an application-specific way. This is complicated by the fact that the subclass of operator which does the actual work may be in a separate process than either the GUI client or the render server. We may need something like an "operator decorator" that remote and/or local clients can construct to present preview results and accept feedback.