Re: [osg-users] Problem loading images when migrating to new OSGViewer

[John Stokes]

Robert,
 
   I tried setting the NearFarRatio to a smaller value, and everything rendered 
as desired. I ended up using:


Code:

viewer-getCamera()-setNearFarRatio(0.2);



 
 This satisfies all my current requirements, so I will keep in mind your good 
advice about the osgdepthpartition example if I need to render a more complex 
scene.

Thanks for your help!

John

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Re: [osg-users] Problem loading images when migrating to new OSGViewer

[Robert Osfield]

Hi John,

On Tue, Sep 28, 2010 at 6:36 PM, John Stokes jstokes2...@yahoo.com wrote:
 When I comment out the updated setComputeNearFarMode line of code, my globe 
 and sky models show up correctly but my plane model disappears. Is there a 
 correct cull setting that I should be using to get everything to display?

 I tried using the COMPUTE_NEAR_FAR_USING_PRIMITIVES and 
 COMPUTE_NEAR_FAR_USING_BOUNDING_VALUES with this call, but I'm not quite 
 sure what bounding value I should be using or if I should be looking at 
 another culling method.

OK, this is good, you've isolated the issue to one of management of
the near/far planes, so now it's a case of finding the appropriate
technique for you type of application/models.

First up the near/far planes are computed during the cull traversal,
using COMPUTE_NEAR_FAR_USING_PRIMITIVES will be more accurate and
provide a tighter bound than COMPUTE_NEAR_FAR_USING_BOUNDING_VOLUMES
but it's more expensive to compute.  Both techniques still use
clamping of the near/far values to avoid the ratio getting too low
which will cause z fighting, this clamping by default pushes out the
near value to obtain a specified near/far ratio.  The
CullSetting::setNearFarRatio(double) sets this value, and Camera
subclasses from CullSettings so you can do:

camera-setNearFarRatio(0.0001); // default value is 0.0005;

It may well be that this in OSG-2.x this near/far ratio is set more
conservatively than OSG-0.9.9 and is the reason why you are seeing
differences.  Have a look at the source code to see what the old
default value was.

--

For scenes which have a very large depth range that tweaking the
near/far planes isn't sufficient it can be useful to using depth
partioning, where you render the scene two or more times, varying the
region that is rendered in each pass.  This osgdepthpartion examples
shows this in action.  This example is a bit out of date and should
really be implemented with viewer slave Cameras rather than in scene
graph Camera, but the principles are the same.

Robert.
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[osg-users] Problem loading images when migrating to new OSGViewer

[John Stokes]

Hi,

I've been migrating some code from OSG 0.9.9 to the latest stable release 
(2.8.3), and I've run into an issue when migrating from OSGProducer::viewer to 
OsgViewer::viewer. I have three models, an airplane.3ds model, a sky.3ds model, 
and a globe.osga model. All three models load correctly (the nodes returned 
from osgDB::readNodeFile are not NULL), but only the airplane model shows up 
when the viewer display is rendered.

The only functions that I needed to change from osgProducer to osgViewer were 
my initialization and update functions. I've made sure to replace osgProducer 
calls with equivalent osgViewer calls when I upgraded (see code below), but is 
there anything I might have missed? 



Code:


3DPlaneViewer::Initialize(){
osgViewer::Viewer* viewer = new osgViewer::Viewer();

//scene root
osg::Group* root = new osg::Group();

//load globe and add transform of globe to root group
osg::Node* globeNode = osgDB::readNodeFile(globe.osga);
osg::MatrixTransform* globeTransform = new osg::MatrixTransform(); 
globeTransform-addChild( globeNode );

//create group for globe and sky
osg::Group*terrainNodes = new Group();
terrainNodes-asGroup()-addChild( globeTransform );

//load airplane
osg::Node* airplaneNode = osgDB::readNodeFile(airplane.3ds);
//specify a location for plane on globe with lat, long, altitude
osg::Matrixd airplaneMatrix;
osg::EllipsoidModel* ellipse-computeLocalToWorldTransformFromLatLongHeight( 
osg::DegreesToRadians(20.0f),osg::DegreesToRadians(-30.0f), 
15000,airplaneMatrix );

//rotate airplane node
airplaneMatrix.preMult( airplaneMatrix.rotate( 
osg::Quat(osg::DegreesToRadians(180.0f), osg::Vec3f( 0, 0, 1 ) )));

//setup matrix wrapper node
osg::MatrixTransform* airplaneTransform = new osg::MatrixTransform(); 
airplaneTransform-getOrCreateStateSet()-setMode(GL_RESCALE_NORMAL,osg::StateAttribute::ON);
 
airplaneTransform-setMatrix(airplaneMatrix); 
airplaneTransform-addChild( airplaneNode );
terrainNodes-asGroup()-addChild( airplaneTransform );


//load and add the sky model
osg::Node* skyNode = osgDB::readNodeFile(sky.3DS);
osg::MatrixTransform* skyTransform = new osg::MatrixTransform();
skyTransform-addChild( skyNode );
terrainNodes-asGroup()-addChild( skyTransform );

root-addChild( terrainNodes );

//realize the scene in the viewer
viewer-setSceneData(root);
viewer-realize(); 

}

3DPlaneViewer::Update()
{

//removed calls to osgProducer::sync()
viewer-updateTraversal();

//do some other updates on other objects in the scene
viewer-frame();
}





Thanks,
John

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Re: [osg-users] Problem loading images when migrating to new OSGViewer

[Robert Osfield]

Hi John,

I don't know the cause of only the airplane showing up, but can
suggest a few things to try to explore what might be going wrong.

First up try loading each of the models with osgviewer and see if each
one loads up OK.

Second write out the completed scene graph to a .osg file just before
you run the viewer code.  Then try to load this scene graph into
osgviewer and see what happens.

On the osgProducer::Viewer - osgViewer::Viewer conversion, with
osgViewer the Viewer::frame() method does the sync, update and event
traversals, and the rendering traversals all together.  Have a look at
the source code to Viewer::frame() to see what it's doing.  You can
break your frame loop out to call each traversals individually if you
want.  Have a look at discussions about this on the mailing
lists/forum and the website, and the examples.

In your case you can safely comment out the call to
viewer-updateTravesal() as viewer-frame() will be doing it for you.

Robert.





On Tue, Sep 28, 2010 at 4:10 PM, John Stokes jstokes2...@yahoo.com wrote:
 Hi,

 I've been migrating some code from OSG 0.9.9 to the latest stable release 
 (2.8.3), and I've run into an issue when migrating from OSGProducer::viewer 
 to OsgViewer::viewer. I have three models, an airplane.3ds model, a sky.3ds 
 model, and a globe.osga model. All three models load correctly (the nodes 
 returned from osgDB::readNodeFile are not NULL), but only the airplane model 
 shows up when the viewer display is rendered.

 The only functions that I needed to change from osgProducer to osgViewer were 
 my initialization and update functions. I've made sure to replace osgProducer 
 calls with equivalent osgViewer calls when I upgraded (see code below), but 
 is there anything I might have missed?



 Code:


 3DPlaneViewer::Initialize(){
 osgViewer::Viewer* viewer = new osgViewer::Viewer();

 //scene root
 osg::Group* root = new osg::Group();

 //load globe and add transform of globe to root group
 osg::Node* globeNode = osgDB::readNodeFile(globe.osga);
 osg::MatrixTransform* globeTransform = new osg::MatrixTransform();
 globeTransform-addChild( globeNode );

 //create group for globe and sky
 osg::Group*terrainNodes = new Group();
 terrainNodes-asGroup()-addChild( globeTransform );

 //load airplane
 osg::Node* airplaneNode = osgDB::readNodeFile(airplane.3ds);
 //specify a location for plane on globe with lat, long, altitude
 osg::Matrixd airplaneMatrix;
 osg::EllipsoidModel* ellipse-computeLocalToWorldTransformFromLatLongHeight( 
 osg::DegreesToRadians(20.0f),osg::DegreesToRadians(-30.0f), 
 15000,airplaneMatrix );

 //rotate airplane node
 airplaneMatrix.preMult( airplaneMatrix.rotate( 
 osg::Quat(osg::DegreesToRadians(180.0f), osg::Vec3f( 0, 0, 1 ) )));

 //setup matrix wrapper node
 osg::MatrixTransform* airplaneTransform = new osg::MatrixTransform();
 airplaneTransform-getOrCreateStateSet()-setMode(GL_RESCALE_NORMAL,osg::StateAttribute::ON);
 airplaneTransform-setMatrix(airplaneMatrix);
 airplaneTransform-addChild( airplaneNode );
 terrainNodes-asGroup()-addChild( airplaneTransform );


 //load and add the sky model
 osg::Node* skyNode = osgDB::readNodeFile(sky.3DS);
 osg::MatrixTransform* skyTransform = new osg::MatrixTransform();
 skyTransform-addChild( skyNode );
 terrainNodes-asGroup()-addChild( skyTransform );

 root-addChild( terrainNodes );

 //realize the scene in the viewer
 viewer-setSceneData(root);
 viewer-realize();

 }

 3DPlaneViewer::Update()
 {

 //removed calls to osgProducer::sync()
 viewer-updateTraversal();

 //do some other updates on other objects in the scene
 viewer-frame();
 }





 Thanks,
 John

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 http://forum.openscenegraph.org/viewtopic.php?p=32136#32136





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Re: [osg-users] Problem loading images when migrating to new OSGViewer

[John Stokes]

Robert,

  Thank you for your insight. I did try loading my models with the standalone 
osgviewer and each of them loaded correctly as did the exported .osg using 
osgDB::writeNodeFile.

  I was testing out commenting out different sections, and I noticed that I had 
this piece of code that I left out in my last post:


Code:

OsgViewer* viewer = new osgViewer::Viewer();
viewer-getCamera()-setClearColor( osg::Vec4(0.2,0.2,1,1) );

//Replace osgProducer::viewer cull setting with new osgViewer setting
//old code: 
viewer-getCullSettings().setComputeNearFarMode(osgUtil::CullVisitor::DO_NOT_COMPUTE_NEAR_FAR);
viewer-getCamera()-setComputeNearFarMode(osgUtil::CullVisitor::DO_NOT_COMPUTE_NEAR_FAR);




When I comment out the updated setComputeNearFarMode line of code, my globe 
and sky models show up correctly but my plane model disappears. Is there a 
correct cull setting that I should be using to get everything to display? 

I tried using the COMPUTE_NEAR_FAR_USING_PRIMITIVES and 
COMPUTE_NEAR_FAR_USING_BOUNDING_VALUES with this call, but I'm not quite sure 
what bounding value I should be using or if I should be looking at another 
culling method.

Thanks,
John[/code]

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