osg2vsg.md

layout	page
title	OpenSceneGraph to VulkanSceneGraph
permalink	/scenegraph/osg2vsg

Smart pointers

OSG	VSG	Notes
osg::ref_ptr<T>	vsg::ref_ptr<T>
osg::observer_ptr<T>	vsg::observer_ptr<T>

Base classes

OSG	VSG	Notes
osg::Referenced	vsg::Object
osg::Object	vsg::Object
META_Object, META_Node	vsg::Inherit<T>	OSG uses C macros while VSG uses Curiously Recurring Template Pattern
	vsg::Allocator	Only VSG has memory allocator.

Data classes

OSG	VSG	Notes
	vsg::Data	Base class with no OSG equivalent
osg::Image	vsg::Value<T>, vsg::Array<T>, vsg::Array2D<>, vsg::Array3D<T>
osg::Uniform	vsg::Value<T>, vsg::Array<T>, vsg::Array2D<>, vsg::Array3D<T>
osg::Array<T>	vsg::Array<T>
osg::IndexArray<T>	vsg::Array<T>

Scene graph nodes

OSG	VSG	Notes
osg::Node	vsg::Node
osg::Group	vsg::Group
osg::Switch	vsg::Switch
osg::LOD	vsg::LOD
osg::PagedLOD	vsg::PagedLOD
osg::Transform	vsg::Transform	Both base classes for providing model transforms
osg::MatrixTransform	vsg::MatrixTransform
osg::MatrixTransform	vsg::AbsoluteTransform	osg::MatrixTransform::setReferenceFrame(ABSOLUTE_RF) equivalent to vsg::AbsoluteTransform
osg::PositionAttitudeTransform		No VSG equivalent
osg::AutoTransform		No VSG equivalent
osg::Billboard		No VSG equivalent - use instanced geometry and vertex shader.

Geometry

OSG	VSG	Notes
osg::Drawable	vsg::Command
osg::Geometry	vsg::Geometry
osg::DrawArrays	vsg::Draw
osg::DrawElements	vsg::DrawIndexed
	vsg::Commands	No OSG equivalent.
	vsg::VertexDraw	No direct OSG equivalent, closest is osg::Geometry
	vsg::VertexIndexDraw	No OSG equivalent, closest is osg::Geometry.
	vsg::BindVertexBuffers	No OSG equivalent.
	vsg::BindIndexBuffers	No OSG equivalent.

State

OSG	VSG	Notes
osg::StateSet	vsg::StateGroup	osg::Group with an osg::StateSet is broadly similar to vsg::StateGroup
osg::StateAttribute	vsg::StateCommand	Both are state base classes, but only vaguely similar
osg::Texture, osg::Texture1D, osg::Texture2D, osg::Texture3D, osg::TextureCubeMap, Texture2DArray	vsg::DescriptorImage, vsg::ImageView, vsg::Image	No direct mapping but together fulfill the same role.
osg::Uniform	vsg::DescriptorBuffer
osg::Light, osg::LightSource	vsg::Light, vsg::AmbientLight, vsg::DirectionalLight, vsg;:PointLight, vsg::SpotLight

Text

OSG	VSG	Notes
osgText::Font	vsg::Font
osgText::Text	vsg::Text
osgText::Text3D		No VSG equivalent
	vsg::TextGroup	No OSG equivalent for efficient rendering of large number of labels

IO

OSG	VSG	Notes
osgDB::readObjectFile(..)	vsg::read(..)
osgDB::readNodeFile(..)	vsg::read_cast<vsg::Node>(..)
osgDB::readImageFile(..)	vsg::read_cast<vsg::Data>(..)
osgDB::writeObjectFile(..)	vsg::write(..)
osgDB::writeNodeFile(..)	vsg::write(..)
osgDB::writeImageFile(..)	vsg::write(..)
osgDB::Options	vsg::Options
osgDB::FileCache	vsg::Options::fileCache
osgDB::ObjectCache	vsg::SharedObjects
osgDB::ReaderWriter	vsg::ReaderWriter
osgDB::Registry	vsg::ObjectFactory
std::string & UTF8	vsg::Path	OSG must be compiled with OSG_USE_UTF8_FILENAME, vsg::Path works like std::filesystem::path
osgDB::DatabasePager	vsg::DatabasePager

Application

OSG	VSG	Notes
osg::Camera	vsg::Camera
osgViewer::View	vsg::View
osgViewer::Viewer	vsg::Viewer
osgViewer::CompositeViewer	vsg::Viewer
osgGA::TrackballManipulator	vsg::Trackball
	vsg::CommandGraph	No OSG equivalent
	vsg::RenderGraph	No OSG equivalent
	vsg::RecordAndSubmitTask	No OSG equivalent
	vsg::ExecuteCommands	No OSG equivalent

Threading

OSG	VSG	Notes
OpenThreads::Thread	std::thread
OpenThreads::Mutex	std::mutex
OpenThreads::ScopedLock	std::lock_guard
OpenThreads::Atomic	std::atomic
OpenThreads::Condition	std::condition_variable
OpenThreads::Barrier	vsg::Barrier
OpenThreads::Block	vsg::Latch
OpenThreads::Affinity	vsg::Affinity
osg::OperationThread	vsg::OperationThread
osg::OperationThread	vsg::OperationQueue
osg::Operation	vsg::Operation
	vsg::ActivityStatus	No OSG equivalent, used to cooperatively release barriers & blocks.
	vsg::FrameBlock	No direct OSG equivalent, loosely OpenThreads::Block.

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