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97 lines
4.3 KiB
C++
97 lines
4.3 KiB
C++
#ifndef OPENMW_COMPONENTS_SCENEUTIL_STATESETCONTROLLER_H
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#define OPENMW_COMPONENTS_SCENEUTIL_STATESETCONTROLLER_H
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#include <components/sceneutil/nodecallback.hpp>
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#include <array>
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#include <map>
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namespace osgUtil
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{
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class CullVisitor;
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}
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namespace SceneUtil
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{
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/// @brief Implements efficient per-frame updating of StateSets.
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/// @par With a naive update there would be race conditions when the OSG draw thread of the last frame
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/// queues up a StateSet that we want to modify for the next frame. To solve this we could set the StateSet to
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/// DYNAMIC data variance but that would undo all the benefits of the threading model - having the cull and draw
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/// traversals run in parallel can yield up to 200% framerates.
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/// @par Must be set as UpdateCallback or CullCallback on a Node. If set as a CullCallback, the StateSetUpdater
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/// operates on an empty StateSet,
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/// otherwise it operates on a clone of the node's existing StateSet.
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/// @par If set as an UpdateCallback, race conditions are prevented using a "double buffering" scheme - we have two
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/// StateSets that take turns,
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/// one StateSet we can write to, the second one is currently in use by the draw traversal of the last frame.
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/// @par If set as a CullCallback, race conditions are prevented by mapping statesets to cull visitors - OSG has two
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/// cull visitors that take turns,
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/// allowing the updater to automatically scale for the number of views.
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/// @note When used as a CullCallback, StateSetUpdater will have no effect on leaf nodes such as osg::Geometry and
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/// must be used on branch nodes only.
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/// @note Do not add the same StateSetUpdater to multiple nodes.
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/// @note Do not add multiple StateSetUpdaters on the same Node as they will conflict - instead use the
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/// CompositeStateSetUpdater.
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class StateSetUpdater : public SceneUtil::NodeCallback<StateSetUpdater>
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{
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public:
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StateSetUpdater();
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StateSetUpdater(const StateSetUpdater& copy, const osg::CopyOp& copyop);
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void operator()(osg::Node* node, osg::NodeVisitor* nv);
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/// Apply state - to override in derived classes
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/// @note Due to the double buffering approach you *have* to apply all state
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/// even if it has not changed since the last frame.
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virtual void apply(osg::StateSet* stateset, osg::NodeVisitor* nv) {}
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/// Apply any state specific to the Left view. Default implementation does nothing. Called after apply() \note
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/// requires the updater be a cull callback
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virtual void applyLeft(osg::StateSet* stateset, osgUtil::CullVisitor* nv) {}
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/// Apply any state specific to the Right view. Default implementation does nothing. Called after apply() \note
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/// requires the updater be a cull callback
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virtual void applyRight(osg::StateSet* stateset, osgUtil::CullVisitor* nv) {}
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/// Set default state - optionally override in derived classes
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/// @par May be used e.g. to allocate StateAttributes.
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virtual void setDefaults(osg::StateSet* stateset) {}
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/// Reset mStateSets, forcing a setDefaults() on the next frame. Can be used to change the defaults if needed.
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void reset();
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private:
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void applyCull(osg::Node* node, osgUtil::CullVisitor* cv);
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void applyUpdate(osg::Node* node, osg::NodeVisitor* nv);
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osg::StateSet* getCvDependentStateset(osgUtil::CullVisitor* cv);
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std::array<osg::ref_ptr<osg::StateSet>, 2> mStateSetsUpdate;
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std::map<osgUtil::CullVisitor*, osg::ref_ptr<osg::StateSet>> mStateSetsCull;
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};
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/// @brief A variant of the StateSetController that can be made up of multiple controllers all controlling the same
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/// target.
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class CompositeStateSetUpdater : public StateSetUpdater
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{
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public:
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CompositeStateSetUpdater();
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CompositeStateSetUpdater(const CompositeStateSetUpdater& copy, const osg::CopyOp& copyop);
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META_Object(SceneUtil, CompositeStateSetUpdater)
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unsigned int getNumControllers();
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StateSetUpdater* getController(int i);
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void addController(StateSetUpdater* ctrl);
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void apply(osg::StateSet* stateset, osg::NodeVisitor* nv) override;
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protected:
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void setDefaults(osg::StateSet* stateset) override;
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std::vector<osg::ref_ptr<StateSetUpdater>> mCtrls;
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};
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}
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#endif
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