Bug Splat on erase!

Dan Rathbun

http://code.google.com/apis/sketchup/docs/ourdoc/modelobserver.html

Read the Introduction section:

Performing any edit operations of your own (such as modifying the model) inside the observer callback should be avoided, as it could cause crashes or model corruption.

if Drawingelement#erase! causes a BugSplat!, try instead:

class MyModelObserver1 < Sketchup;;ModelObserver
   def onPreSaveModel(model)
      selection = model.selection
      unless selection.empty?
        model.active_entities.erase_entities(selection[0])
        model.active_view.refresh() 
      end
   end
end

... but may not work either.

voljanko

Uff,your solution didn't resolved the problem(same result),but helped to understand it.
It seems that the onPreSaveModel observer is not the real pre save observer.I would need a pre-pre save observer.

Dan Rathbun

A SelectionObserver ?

voljanko

I have a group that is generated when a tool is activated and deleted when a tool is deactivated.
The problem is when the model is saved when a tool is active (auto save or user save).
I don't want that group to be saved in the model,so I have implemented the onPreSaveModel observer to delete the group.
But I cannot get rid of the BugSplat.

Dan Rathbun

Make sure you read (and bookmark,) these topics:

And ThomThom webpage:

State of Google SketchUp's Observers

@unknownuser said:

(http://forums.sketchucation.com/viewtopic.php?f)":3um4efab]Other notes
Another thing I learned was that doing modifications to the model on observer events can cause lots of problems.

•If a script is doing something which trigger an event that modifies the model it will break the undo stack. I also seem that it can make SU unstable. You could potentially cause infinite loops.
•After consulting with Scott it seems that queueing up a list of modifications to be done to the model and executing the list on ModelObserver.onTransactionCommit is the most reliable way to do it.

thomthom

Mat I ask what your temp group do? What is it function?
(just wondering if there might be alternatives to creating temp geometry here - such as using view.draw for instance...)

voljanko

@thomthom said:

Mat I ask what your temp group do? What is it function?

Im using it to highlight some surfaces ,because I can draw only lines (and points and text) with view.draw.

Is there any samples of using the ModelObserver.onTransactionCommit and other onTransaction functions?
I cannot figured out what are they for.

thomthom

@voljanko said:

@thomthom said:

Mat I ask what your temp group do? What is it function?

Im using it to highlight some surfaces ,because I can draw only lines (and points and text) with view.draw.

Incorrect - you can draw filled shapes with view.draw . GL_TRIANGLES, GL_TRIANGLE_STRIP,
GL_TRIANGLE_FAN, GL_QUADS, GL_QUAD_STRIP, GL_POLYGON will let you do that. But note that in SU prior to version 8 the fill is always black. But as of v8 it works great. You can even use transparent fill.

voljanko

Thank you for pointing this out,I was really stacked wit this BugSplat.
So, more new functions to learn.

voljanko

But also Dan's suggestions have positive results:
In the activate method of the tool I have put the

Sketchup.active_model.start_operation "myTool",true,true,false

And I have put the

Sketchup.active_model.abort_operation

in the deactivate method of the tool and in the onPreSaveModel model observer.
Now the group is disappear before saving the model.
Thank you both.