libosgearth-dev 2.9.0+dfsg-1 / usr / include / osgEarth / StateSetCache

/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
* Copyright 2016 Pelican Mapping
* http://osgearth.org
*
* osgEarth is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>
*/
#ifndef OSGEARTH_STATE_SET_CACHE_H
#define OSGEARTH_STATE_SET_CACHE_H 1

#include <osgEarth/Common>
#include <osgEarth/ThreadingUtils>
#include <osg/StateSet>
#include <set>

namespace osgEarth
{
    /**
     * Cache for optimizing state set sharing. Running a sharing pass on a node
     * (with the optimize method, or one of the consolidate methods) will reduce
     * any duplicate state attribute or state sets down to a single instance.
     * This can help reduce the number of state changes that occur when the node
     * is rendered, though this is not guanranteed.
     *
     * This class is not thread safe. That means:
     *
     * You should ONLY use it on a node that contains nothing in the LIVE scene
     * graph. It will replace state attributes and state sets on nodes that it finds;
     * this is illegal if those objects are in use in another thread. So the typical
     * use case is to run this on a newly-loaded model or on a newly-created node 
     * graph before adding it to the live graph.
     *
     * It's OK for the contents of the cache itself to be present elsewhere, even
     * in the live scene graph. These will not altered. So for example, you can re-use
     * the same StateSetCache instance to optimize more than one new graph.
     */
    class OSGEARTH_EXPORT StateSetCache : public osg::Referenced
    {
    public:
        /**
         * Constructs a new cache.
         */
        StateSetCache();

        /**
         * Caps the size of the cache.
         */
        void setMaxSize(unsigned maxSize);

        /**
         * Check whether a StateSet is eligible for sharing.
         */
        bool eligible( osg::StateSet* stateSet ) const;

        /**
         * Check whether a StateAttribute is eligible for sharing.
         */
        bool eligible( osg::StateAttribute* attr ) const;

        /** 
         * Scans a graph and combines equivalents state attributes into
         * single shared attribute. Skips any attribute (or stateset)
         * with dynamic data variance
         */
        void consolidateStateAttributes(osg::Node* node);

        /**
         * Scans a graph and combines equivalent statesets into a single
         * shared stateset. Skips any stateset with dynamic data variance.
         */
        void consolidateStateSets(osg::Node* node);

        /**
         * Calls consolidateStateAttributes followed by consolidateStateSets.
         */
        void optimize(osg::Node* node);

        /**
         * Looks in the cache for a stateset matching the input. If found,
         * returns the cached one in output. If not found, stores the input 
         * in the cache and returns the same one in output.
         *
         * Must use ref_ptrs for thread safely
         */
        bool share( 
            osg::ref_ptr<osg::StateSet>& input, 
            osg::ref_ptr<osg::StateSet>& output,
            bool                         checkEligible =true );

        /**
         * Looks in the attribute cache for an attribute matching the input.
         * If found, returns the cached one in output. If not found, stores
         * the input in the cache and returns the same one in output.
         *
         * Must use ref_ptrs for thread safely
         */
        bool share(
            osg::ref_ptr<osg::StateAttribute>& input,
            osg::ref_ptr<osg::StateAttribute>& output,
            bool                               checkEligible =true );

        /**
         * Number of statesets in the cache.
         */
        unsigned size() const { return _stateSetCache.size(); }

        /**
         * Clears out the cache.
         */
        void clear();

        void dumpStats();

    protected: 

        virtual ~StateSetCache();

        struct CompareStateSets {
            bool operator()(
                const osg::ref_ptr<osg::StateSet>& lhs,
                const osg::ref_ptr<osg::StateSet>& rhs) const {
                    return lhs->compare(*(rhs.get()), true) < 0;
            }
        };
        typedef std::set< osg::ref_ptr<osg::StateSet>, CompareStateSets> StateSetSet;
        StateSetSet _stateSetCache;

        struct CompareStateAttributes {
            bool operator()(
                const osg::ref_ptr<osg::StateAttribute>& lhs,
                const osg::ref_ptr<osg::StateAttribute>& rhs) const {
                    return lhs->compare(*rhs.get()) < 0;
            }
        };
        typedef std::set< osg::ref_ptr<osg::StateAttribute>, CompareStateAttributes> StateAttributeSet;
        StateAttributeSet _stateAttributeCache;

        mutable Threading::Mutex _mutex;

        void prune();
        void pruneIfNecessary();
        unsigned _maxSize;
        unsigned _pruneCount;

        //stats
        unsigned _attrShareAttempts;
        unsigned _attrsIneligible;
        unsigned _attrShareHits;
        unsigned _attrShareMisses;
    };
}

#endif // OSGEARTH_STATE_SET_CACHE_H