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CoreOSG

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State

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State - state sets, attributes, modes and per context state

• osg::StateSet - a container for a set of modes and attributes with support for multitexturing


• osg::StateSet::setMode(GL_LIGHTING,osg::StateAttribute::ON) - you can use OpenGL enums modes directly


• osg::StateSet::setAttribute(attribute) - for adding general state attributes


• osg::StateSet::setTextureMode(textureunit,GL_TEXTURE_2D,osg::StateAttribute::ON) - for setting texture modes


• osg::StateSet::setTextureAttribute(textureunit,texattribute) - for add texure attribute


• Texture unit go from 0 upwards, no upper limit other than imposed by graphics cards/drivers.


• osg::StateAttributes - encapsulates OpenGL state atribute values


• 24 subclasses from osg::StateSet, covers most OpenGL state, including many extensions


• For non texturing related state add to a StateSet with setAttribute(..)


• For texture related state add to a StateSet with setTextureAttribute(..) since you need the texture unit.
  osg::StateAttribute::isTextureAttribute() will return true for texture related state.


• You'll get a warning on the console if you use the wrong set(Texture)Attribute() assignement.


• osg::State - manages graphics state per graphics context


• Not part of the scene graph (wheras StateSet/Attribute are part of the scene)


• Used by the Draw traversal to manage the current graphics state.


• Supports fine grained (per mode and per attribute) lazy state updating to minimize OpenGL state changes.


• One per graphics context, use osg::State::setContextID(contextID) to set which context
  contextID can be 0,1,2.... for multiple graphics pipes/context
  contextID is not a GLX graphics context, just a simple offset into internal multibuffer arrays