[osg-users] General Users starting questions in OSG 3.0, 3.5

[michael kapelko]

Hi.

> 1. Is it always possible to avoid using Shaders, in OSG programming, to acheive any particular task?
You can use fixed function pipeline only on desktops, this restriction
comes from driver manufacturers. If you're fine with desktops only,
OSG can do without shaders.

> 2. Is it always possible to avoid using OSG Macros, in order to acheive
any particular task?
Which macros exactly? If you refer to META_* macros, those are only
necessary if you want to modify OSG itself or if you want to create an
easy-to-use OSG nodekit like osgEarth: http://osgearth.org/
If you simply use OSG to render things for you, you don't need OSG
macros in your own code.

> 3. Much of the dat astorage an input in the Beginner's Guide is Done using Vectors. Is it possible to do things using 2D and 3D Point objects for things too?
I've read the book a few years ago, so can't remember that part. It
would be great if you could clarify the question.

> 4. How can I convert between a Shape object and a Drawable object successfully using OSG code?
If you want to add a shape into OSG scene, then here's how to create
an osg::MatrixTransform that you can add to osg::Group or pass to
osg::Viewer::setSceneData():
* https://github.com/OGStudio/openscenegraph-cross-platform-examples/blob/master/features/scene/createShape.cpp
* https://github.com/OGStudio/openscenegraph-cross-platform-examples/blob/master/features/scene/createSphere.cpp

> 5. Is it possible to just directly create an object from a function or method name in C++?
A code snipper would help, since I don't have the book around me.

> 6. What is the most comprehensive and simple Blender3D to OSG file saving format recommended to be?
I use osgexport from here:
https://github.com/cedricpinson/osgexport/tree/master/build
Here's a detailed guide on how to create a model in Blender and use it
in OSG: https://github.com/OGStudio/openscenegraph-cross-platform-guide/tree/master/1.1.CreateCube



On Mon, 15 Oct 2018 at 06:59, A Z <poweruserm at live.com.au> wrote:
>
> I have just finished going through 'OpenSceneGraph 3.0 Beginner's Guide'
> and have been left with the following pretty simple questions.
>
> -Is it always possible to avoid using Shaders, in OSG programming,
> to acheive any particular task?
>
> -Is it always possible to avoid using OSG Macros, in order to acheive
> any particular task?
>
> -Much of the dat astorage an input in the Beginner's Guide is Done using Vectors.
> Is it possible to do things using 2D and 3D Point objects for things too?
>
> -How can I convert between a Shape object and a Drawable object successfully
> using OSG code?
>
> -I was a little put back in the Beginner's Guide about code situations like
>
> Page 197 , 5)  new SwitchingCallBack
>
> Is it possible to just directly create an object from a function or method name in C++?
> Or does this example instantiate a class, that has defaulting, automatically-to-be called
> logic always placed inside an operator() method?
>
> -In a situation where I plan to create my 3D objects in Blender 3D, wit their points,
> edges, surfaces, materials and or textures, and save them to file, at this time,
> what is the most comprehensive and simple Blender3D to OSG file saving format
> recommended to be?
>
> Is there one that can include Animation timeline information,
> holding keyframes, that OSG can read in?  Is there one that recognises Bones and character
> rigging?  What is the best Blender 3D plugin to use (not an additional OSG plugin)?
> What comes recommended for this from OSG?
>
> Many thanks, yours truly,
>
> poweruserm.
>
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