[osg-users] Problems porting from osg-3.4.0 to osg-3.6.0

[Robert Osfield]

Hi Herman,

To make sure that shadow techniques properly handling applications
opening new windows and properly handle clean up they need to
implement the resizeGLObjectBuffers(..) and releaseGLObjects(..)
methods.  In 3.6.x to ensure this is done these methods are pure
virtual forcing the subclasses to implement them.  The ShadowTechnique
implementation looks like:

        /** Resize any per context GLObject buffers to specified size. */
        virtual void resizeGLObjectBuffers(unsigned int maxSize) = 0;

        /** If State is non-zero, this function releases any
associated OpenGL objects for
           * the specified graphics context. Otherwise, releases OpenGL objects
           * for all graphics contexts. */
        virtual void releaseGLObjects(osg::State* = 0) const = 0;

META_Object can only be used with concrete classes so you can't use it
in this for ShadowTechnique.

For the custom ShadowTechnique you simply need to provide
resizeGLObjectBuffers(..) and releaseGLObjects(..).  To see what they
would need to be have a look at the various ShadowTechnique subclasses
in src/osgShadow.

Cheers,
Robert.
On Thu, 13 Sep 2018 at 07:48, Herman Varma <hermanvarma at eastlink.ca> wrote:
>
> Hello I am having trouble porting  Ben Discoe’s VTP software from openSceneGraph-3.4.0 to osg-3.6.2
>
> The problem lies in implementing the macro to replace META_object in shadowTechnique.h as depicted below.
> . Can someone point out where my problem is.
>
> /** CSimpleInterimShadowTechnique provides an implementation of a depth map shadow tuned to the needs of VTP.*/
> class CSimpleInterimShadowTechnique : public osgShadow::ShadowTechnique
> {
> public:
>
> //  working **********************  in openSceneGraph-3.4.0
> //     CSimpleInterimShadowTechnique();
> //     CSimpleInterimShadowTechnique(const
> //        CSimpleInterimShadowTechnique& es, const osg::CopyOp&
> //        copyop=osg::CopyOp::SHALLOW_COPY);
> //     META_Object(osgShadow, CSimpleInterimShadowTechnique);
> //***********************************************************
>
> // Macro not working *****************in openSceneGraph-3.6.2
>        CSimpleInterimShadowTechnique();
>        CSimpleInterimShadowTechnique(const CSimpleInterimShadowTechnique& es, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY);
>
>        virtual bool isSameKindAs(const osg::Object* obj) const { return dynamic_cast<const CSimpleInterimShadowTechnique*>(obj) != NULL; } \
>        virtual const char* libraryName() const { return "osgShadow"; }\
>        virtual const char* className() const { return "CSimpleInterimShadowTechnique"; }
>
>
> //**************************************************************
>
> In the new implementation I am getting a C2259 error
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): error C2259: 'CSimpleInterimShadowTechnique': cannot instantiate abstract class
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): note: due to following members:
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): note: 'osg::Object *osg::Object::cloneType(void) const': is abstract
>
> 2>c:\apis\openscenegraph-3.6.2\build\include\osg\object(80): note: see declaration of 'osg::Object::cloneType'
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): note: 'osg::Object *osg::Object::clone(const osg::CopyOp &) const': is abstract
>
> 2>c:\apis\openscenegraph-3.6.2\build\include\osg\object(84): note: see declaration of 'osg::Object::clone'
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): note: 'void osgShadow::ShadowTechnique::resizeGLObjectBuffers(unsigned int)': is abstract
>
> 2>c:\apis\openscenegraph-3.6.2\build\include\osgshadow\shadowtechnique(66): note: see declaration of 'osgShadow::ShadowTechnique::resizeGLObjectBuffers'
>
> 2>c:\vtp_vsc\terrainsdk\vtlib\vtosg\nodeosg.cpp(1026): note: 'void osgShadow::ShadowTechnique::releaseGLObjects(osg::State *) const': is abstract
>
> 2>c:\apis\openscenegraph-3.6.2\build\include\osgshadow\shadowtechnique(71): note: see declaration of 'osgShadow::ShadowTechnique::releaseGLObjects'
>
> The area where the error manifests is in this section of nodeOSG.cpp
>
> //////////////////////////////////////////////////////////////////////
> // vtShadow
> //
>
> vtShadow::vtShadow(const int ShadowTextureUnit, int LightNumber) :
>        m_ShadowTextureUnit(ShadowTextureUnit), m_LightNumber(LightNumber)
> {
>        setReceivesShadowTraversalMask(ReceivesShadowTraversalMask);
>        setCastsShadowTraversalMask(CastsShadowTraversalMask);
>
> #if VTLISPSM
>        osg::ref_ptr<CLightSpacePerspectiveShadowTechnique> pShadowTechnique = new CLightSpacePerspectiveShadowTechnique;
>        // No need to set the BaseTextureUnit as the default of zero is OK for us
>        // But the ShadowTextureUnit might be different (default 1)
>        pShadowTechnique->setShadowTextureUnit(m_ShadowTextureUnit);
>        pShadowTechnique->setLightNumber(m_LightNumber);
> #else
>        //errorC2259 cannot instantiate abstract class in openSceneGraph-3.6.2
>        //statement working in osg-3.4.0
>        osg::ref_ptr<CSimpleInterimShadowTechnique> pShadowTechnique = new CSimpleInterimShadowTechnique;//*****************************Error here
> #endif
>
> #if !VTLISPSM
> #if VTDEBUGSHADOWS
>        // add some instrumentation
>        pShadowTechnique->m_pParent = this;
> #endif
>
>        pShadowTechnique->SetLightNumber(LightNumber);
>        pShadowTechnique->SetShadowTextureUnit(m_ShadowTextureUnit);
>        pShadowTechnique->SetShadowSphereRadius(50.0);
> #endif
>        setShadowTechnique(pShadowTechnique.get());
>
>        SetOsgNode(this);
> }
>
> Help would be appreciated
>
>
> Cheers,
> Herman
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=74726#74726
>
>
>
>
>
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