Re: [osg-users] osg::Image Serialization
Hi Jeremy, 2011/8/18 Jeremy Moles : > I'm not entirely sure this is accurate; if you look at osgimagesequence > example, it lets you write the file out to disk: > > osgimagesequence -o foo.osgt > > ...but that file isn't readable by OSG. In fact, I had no trouble ever > writing my custom Image to disk, only reading it back in. > > However, the serializer backend is very complex (or rather, quite > abstracted away in macros), and so I've found it difficult to track down > where exactly to investigate... > So it may be a bug of image serializers. I'll try to catch up as soon as possible. I'm currently work on the latest chapter of my second OSG book and the dead line is coming. So I have to focus on the writing work this weekend. I will announce the progress of the book OpenSceneGraph Cookbook later in the community and then get back to the serializer problem with you. :-) Wang Rui ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osg::Image Serialization
On Wed, 2011-08-17 at 08:48 +0800, Wang Rui wrote: > Hi Jeremy and Robert, > > In fact the osg::Image class can be derived and it is possible to > write serializers for the subclasses. In > osgWrappers/serializers/osg/ImageStream.cpp you will find an example > which has no difference from other serializers. I'm not sure if this > could work for osgCairo images, but I think a subclass that doesn't > change osg::Image's basic functionalities can work fine with > serializers at present. I'm not entirely sure this is accurate; if you look at osgimagesequence example, it lets you write the file out to disk: osgimagesequence -o foo.osgt ...but that file isn't readable by OSG. In fact, I had no trouble ever writing my custom Image to disk, only reading it back in. However, the serializer backend is very complex (or rather, quite abstracted away in macros), and so I've found it difficult to track down where exactly to investigate... > After reviewing the source code, I think it also possible to replace > the readImage() and writeImage() in Input/OutputStream classes with an > Image serializer, too. I can't remember why I use special > reader/writer functions to handle images. Maybe it is only a > plagiarism of old osgDB::Input/Output class' methods. :-P Perhaps this is where I should look then. :) > Cheers, > > Wang Rui > > > 2011/8/17 Jeremy Moles : > > Hello everyone; this is probably a question only a few people could > > possibly, answer (Robert, Wang), but here goes: > > > > I have created a derived osg::Image class (osgCairo::Image), and this > > has worked just fine for the last few years. However, I want to add > > strong serialization support for my nodekits, and I'm finding > > customizing an Images behavior in the serialization code is quite > > difficult. > > > > Images are treated as special kinds of Objects, so any custom behavior > > you might add confuses the base serializers, and there doesn't appear to > > be any way to avoid this. > > > > My question is: should the serialization backend be modified to support > > osg::Image subclasses, or should programmers be encouraged NOT to derive > > from osg::Image directly and instead create "contains-a" objects > > instead? > > > > ___ > > osg-users mailing list > > osg-users@lists.openscenegraph.org > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osg::Image Serialization
Hi Jeremy and Robert, In fact the osg::Image class can be derived and it is possible to write serializers for the subclasses. In osgWrappers/serializers/osg/ImageStream.cpp you will find an example which has no difference from other serializers. I'm not sure if this could work for osgCairo images, but I think a subclass that doesn't change osg::Image's basic functionalities can work fine with serializers at present. After reviewing the source code, I think it also possible to replace the readImage() and writeImage() in Input/OutputStream classes with an Image serializer, too. I can't remember why I use special reader/writer functions to handle images. Maybe it is only a plagiarism of old osgDB::Input/Output class' methods. :-P Cheers, Wang Rui 2011/8/17 Jeremy Moles : > Hello everyone; this is probably a question only a few people could > possibly, answer (Robert, Wang), but here goes: > > I have created a derived osg::Image class (osgCairo::Image), and this > has worked just fine for the last few years. However, I want to add > strong serialization support for my nodekits, and I'm finding > customizing an Images behavior in the serialization code is quite > difficult. > > Images are treated as special kinds of Objects, so any custom behavior > you might add confuses the base serializers, and there doesn't appear to > be any way to avoid this. > > My question is: should the serialization backend be modified to support > osg::Image subclasses, or should programmers be encouraged NOT to derive > from osg::Image directly and instead create "contains-a" objects > instead? > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osg::Image Serialization
Hi Jeremy, I would have though it would be appropriate to support subclassing of osg::Image in the serializers. I'll defer to Rui to answer the specifics of how we might go about this. Robert. On Tue, Aug 16, 2011 at 5:42 PM, Jeremy Moles wrote: > Hello everyone; this is probably a question only a few people could > possibly, answer (Robert, Wang), but here goes: > > I have created a derived osg::Image class (osgCairo::Image), and this > has worked just fine for the last few years. However, I want to add > strong serialization support for my nodekits, and I'm finding > customizing an Images behavior in the serialization code is quite > difficult. > > Images are treated as special kinds of Objects, so any custom behavior > you might add confuses the base serializers, and there doesn't appear to > be any way to avoid this. > > My question is: should the serialization backend be modified to support > osg::Image subclasses, or should programmers be encouraged NOT to derive > from osg::Image directly and instead create "contains-a" objects > instead? > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osg::Image Serialization
On Tue, 2011-08-16 at 12:42 -0400, Jeremy Moles wrote: > Hello everyone; this is probably a question only a few people could > possibly, answer (Robert, Wang), but here goes: > > I have created a derived osg::Image class (osgCairo::Image), and this > has worked just fine for the last few years. However, I want to add > strong serialization support for my nodekits, and I'm finding > customizing an Images behavior in the serialization code is quite > difficult. > > Images are treated as special kinds of Objects, so any custom behavior > you might add confuses the base serializers, and there doesn't appear to > be any way to avoid this. > > My question is: should the serialization backend be modified to support > osg::Image subclasses, or should programmers be encouraged NOT to derive > from osg::Image directly and instead create "contains-a" objects > instead? As an addendum, this may simply be a misuse on my part. Perhaps if someone is deriving from osg::Image, that person should also consider creating a custom image "type" and, thus, writing an osgPlugin for their image type to do the various kinds of extra stuff they need to do. For example, in osgCairo, though I may actually be using PNG data, I could create a ".cairo" file type which will force my custom loader instead of the default loader (which will allow me to do things like pre-multiply the alpha, which Cairo expects internally). Just thinking out loud here. :) > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] osg::Image Serialization
Hello everyone; this is probably a question only a few people could possibly, answer (Robert, Wang), but here goes: I have created a derived osg::Image class (osgCairo::Image), and this has worked just fine for the last few years. However, I want to add strong serialization support for my nodekits, and I'm finding customizing an Images behavior in the serialization code is quite difficult. Images are treated as special kinds of Objects, so any custom behavior you might add confuses the base serializers, and there doesn't appear to be any way to avoid this. My question is: should the serialization backend be modified to support osg::Image subclasses, or should programmers be encouraged NOT to derive from osg::Image directly and instead create "contains-a" objects instead? ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
