[osg-users] Possible Bug in osg::AutoTransform

[Peter Gebauer]

Hi!

I've been experimenting with transformations, what happens that the 
AutoTransform updates using automatic scaling to the screen.
You can set auto scale to false using setAutoScaleToScreen(bool) and
set your scale manually using setScale(const Vec3f&).

If you still want auto scaling enabled that can be done too by using 
a PositionAttitudeTransform as a child of AutoTransform.
It works as one would suspect, you just have to compensate for any previous, 
automatic scaling.

/Peter

On 2007-07-24 (Tue) 10:25, Cysneros, Nelson SPAWAR wrote:
> Thank you Robert,
> 
> I think I'm unclear on how to scale the subgraph.  
> 
> I tried adding a PositionAttitudeTransform object as a child of the
> AutoTransform and scaling it.  I also tried adding the AutoTransform as
> a child to a PositionAttitudeTransform that is scaled.  Neither seemed
> to work.  Am I doing something wrong?  
> 
> My goal is to have my drawable object the same size no matter how much
> you zoom in or out, but I need to control the initial size.  Is their a
> better way of doing this?
> 
> 
> Code Snippets:
> 
> PositionAttitudeTransform object as a child of the AutoTransform
> ------------------------------------------------------------------
> 
>       osg::Group* root = new osg::Group();
>       osg::Geode* geode = new osg::Geode();
> 
> 	//AutoTrans
> 	osg::AutoTransform* at  = new osg::AutoTransform;
> 	at->setAutoScaleToScreen(true);
>       at->setAutoRotateMode(osg::AutoTransform::ROTATE_TO_SCREEN);
> 
> 	//Initial Scale
> 	osg::PositionAttitudeTransform* postrans = new
> osg::PositionAttitudeTransform();
> 	osg::Vec3 modelScale;
> 	double value = 10000;
> 	modelScale.set(value,value,value); 
> 	postrans->setScale( modelScale ); 
> 	
> 	geode->addDrawable(new Symbol(getEntityTD()));
>       postrans->addChild(geode);
> 
> 	at->addChild(postrans); 
> 	
> 	root->addChild(at);
>    
> 	return root;
> 
> 
> AutoTransform as a child to a PositionAttitudeTransform
> ------------------------------------------------------------------
> 
>       osg::Group* root = new osg::Group();
>       osg::Geode* geode = new osg::Geode();
> 
> 	//AutoTrans
> 	osg::AutoTransform* at  = new osg::AutoTransform;
> 	at->setAutoScaleToScreen(true);
>       at->setAutoRotateMode(osg::AutoTransform::ROTATE_TO_SCREEN);	
> 	geode->addDrawable(new Symbol(getEntityTD()));
>       at->addChild(geode);
> 
> 	//Initial Scale
> 	osg::PositionAttitudeTransform* postrans = new
> osg::PositionAttitudeTransform();
> 	osg::Vec3 modelScale;
> 	double value = 10000;
> 	modelScale.set(value,value,value); 
> 	postrans->setScale( modelScale ); 
> 
> 	postrans->addChild(at);
> 	
> 	root->addChild(postrans);
>    
> 	return root;
> 
> 
> -----Original Message-----
> From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Robert
> Osfield
> Sent: Tuesday, July 24, 2007 1:16 AM
> To: osg-users at lists.openscenegraph.org
> Subject: Re: [osg-users] Possible Bug in osg::AutoTransform
> 
> 
> Hi Nelson,
> 
> This isn't a bug, when you do scale to screen what it does it uses puts
> the subgraph into screen space by adjusting the scale parameter to fit.
> If you want to change the scale of the subgraph then it'll need to built
> with screen space coords in mind.
> 
> Robert.
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>