C++ State::getContextID方法代码示例

void AtomicCounterBufferBinding::readData(osg::State & state, osg::UIntArray & uintArray) const
{
    if (!_bufferObject) return;

    GLBufferObject* bo = _bufferObject->getOrCreateGLBufferObject( state.getContextID() );
    if (!bo) return;


    GLint previousID = 0;
    glGetIntegerv(GL_ATOMIC_COUNTER_BUFFER_BINDING, &previousID);

    if (static_cast<GLuint>(previousID) != bo->getGLObjectID())
        bo->_extensions->glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, bo->getGLObjectID());

    GLubyte* src = (GLubyte*)bo->_extensions->glMapBuffer(GL_ATOMIC_COUNTER_BUFFER,
                                                          GL_READ_ONLY_ARB);
    if(src)
    {
        size_t size = osg::minimum<int>(_size, uintArray.getTotalDataSize());
        memcpy((void*) &(uintArray.front()), src+_offset, size);
        bo->_extensions->glUnmapBuffer(GL_ATOMIC_COUNTER_BUFFER);
    }

    if (static_cast<GLuint>(previousID) != bo->getGLObjectID())
        bo->_extensions->glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, static_cast<GLuint>(previousID));
}

void Validator::apply(osg::State& state) const
{
    if (!_effect) return;

    if (_effect->_tech_selected[state.getContextID()] == 0) {
        Effect::Technique_list::iterator i;
        int j = 0;
        for (i=_effect->_techs.begin(); i!=_effect->_techs.end(); ++i, ++j) {
            if ((*i)->validate(state)) {
                _effect->_sel_tech[state.getContextID()] = j;
                _effect->_tech_selected[state.getContextID()] = 1;
                return;
            }
        }
        OSG_WARN << "Warning: osgFX::Validator: could not find any techniques compatible with the current OpenGL context" << std::endl;
    }
}

bool Technique::validate(osg::State& state) const
{
    typedef std::vector<std::string> String_list;
    String_list extensions;

    getRequiredExtensions(extensions);

    for (String_list::const_iterator i=extensions.begin(); i!=extensions.end(); ++i) {
        if (!osg::isGLExtensionSupported(state.getContextID(),i->c_str())) return false;
    }

    return true;
}

std::string DepthPeelBin::createFileName( osg::State& state, int pass, bool depth )
{
    unsigned int contextID = state.getContextID();
    int frameNumber = state.getFrameStamp()->getFrameNumber();
    std::ostringstream ostr;
    ostr << std::setfill( '0' );
    ostr << "f" << std::setw( 6 ) << frameNumber <<
        "_c" << std::setw( 2 ) << contextID << "_";

    ostr << "peel_part" << _partitionNumber;
    if( pass == -1 )
        ostr << "_a";
    else
        ostr << "_b" << std::setw( 2 ) << pass;
    if( depth )
        ostr << "_z";
    ostr << ".png";
    return( ostr.str() );
}

void
DepthPeelBin::PerContextInfo::cleanup( const osg::State& state )
{
    TRACEDUMP("  PerContextInfo::cleanup");

    glDeleteTextures( 3, _depthTex );
    _depthTex[ 0 ] = _depthTex[ 1 ] = _depthTex[ 2 ] = 0;

    glDeleteTextures( 1, &_colorTex );
    _colorTex = 0;

    osg::FBOExtensions* fboExt( osg::FBOExtensions::instance( state.getContextID(), true ) );
    osgwTools::glBindFramebuffer( fboExt, GL_FRAMEBUFFER_EXT, 0 );
    osgwTools::glDeleteFramebuffers( fboExt, 1, &_fbo );
    _fbo = 0;

    _glDeleteQueries( 1, &_queryID );
    _queryID = 0;

    _init = false;
}

void Font::Glyph::draw(osg::State& state) const
{
    GLuint& globj = _globjList[state.getContextID()];

    // call the globj if already set otherwise compile and execute.
    if( globj != 0 )
    {
        glCallList( globj );
    }
    else 
    {
        globj = glGenLists( 1 );
        glNewList( globj, GL_COMPILE_AND_EXECUTE );

        glPixelStorei(GL_UNPACK_ALIGNMENT,getPacking());
        glDrawPixels(s(), t(),
                     (GLenum)getPixelFormat(),
                     (GLenum)getDataType(),
                     data() );

        glEndList();
    }
}

void GlyphTexture::apply(osg::State& state) const
{
    // get the contextID (user defined ID of 0 upwards) for the 
    // current OpenGL context.
    const unsigned int contextID = state.getContextID();

    if (contextID>=_glyphsToSubload.size())
    {
        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);

        // graphics context is beyond the number of glyphsToSubloads, so
        // we must now copy the glyph list across, this is a potential
        // threading issue though is multiple applies are happening the
        // same time on this object - to avoid this condition number of
        // graphics contexts should be set before create text.
        for(unsigned int i=_glyphsToSubload.size();i<=contextID;++i)
        {
            GlyphPtrList& glyphPtrs = _glyphsToSubload[i];
            for(GlyphRefList::const_iterator itr=_glyphs.begin();
                itr!=_glyphs.end();
                ++itr)
            {
                glyphPtrs.push_back(itr->get());
            }
        }
    }


    const Extensions* extensions = getExtensions(contextID,true);
    bool generateMipMapSupported = extensions->isGenerateMipMapSupported();

    // get the texture object for the current contextID.
    TextureObject* textureObject = getTextureObject(contextID);
    
    bool newTextureObject = (textureObject == 0);

    if (newTextureObject)
    {
        GLint maxTextureSize = 256;
        glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);
        if (maxTextureSize < getTextureWidth() || maxTextureSize < getTextureHeight())
        {
            OSG_WARN<<"Warning: osgText::Font texture size of ("<<getTextureWidth()<<", "<<getTextureHeight()<<") too large, unable to create font texture."<<std::endl;
            OSG_WARN<<"         Maximum supported by hardward by native OpenGL implementation is ("<<maxTextureSize<<","<<maxTextureSize<<")."<<std::endl;
            OSG_WARN<<"         Please set OSG_MAX_TEXTURE_SIZE lenvironment variable to "<<maxTextureSize<<" and re-run application."<<std::endl;
            return;
        }
        
        // being bound for the first time, need to allocate the texture

        _textureObjectBuffer[contextID] = textureObject = osg::Texture::generateTextureObject(
                this, contextID,GL_TEXTURE_2D,1,GL_ALPHA,getTextureWidth(), getTextureHeight(),1,0);

        textureObject->bind();


        applyTexParameters(GL_TEXTURE_2D,state);

        
        // need to look at generate mip map extension if mip mapping required.
        switch(_min_filter)
        {
        case NEAREST_MIPMAP_NEAREST:
        case NEAREST_MIPMAP_LINEAR:
        case LINEAR_MIPMAP_NEAREST:
        case LINEAR_MIPMAP_LINEAR:
            if (generateMipMapSupported)
            {
                glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,GL_TRUE);
            }
            else glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, LINEAR);
            break;
        default:
            // not mip mapping so no problems.
            break;
        }
        
        unsigned int imageDataSize = getTextureHeight()*getTextureWidth();
        unsigned char* imageData = new unsigned char[imageDataSize];
        for(unsigned int i=0; i<imageDataSize; ++i)
        {
            imageData[i] = 0;
        }
        

        // allocate the texture memory.
        glTexImage2D( GL_TEXTURE_2D, 0, GL_ALPHA,
                getTextureWidth(), getTextureHeight(), 0,
                GL_ALPHA,
                GL_UNSIGNED_BYTE,
                imageData );
                
        delete [] imageData;
    
    }
    else
    {
        // reuse texture by binding.
        textureObject->bind();
        
//.........这里部分代码省略.........

void VertexArrayState::setArray(ArrayDispatch* vad, osg::State& state, const osg::Array* new_array)
{
    if (new_array)
    {
        if (!vad->active)
        {
            vad->active = true;
            _activeDispatchers.push_back(vad);
        }

        if (vad->array==0)
        {
            GLBufferObject* vbo = isVertexBufferObjectSupported() ? new_array->getOrCreateGLBufferObject(state.getContextID()) : 0;
            if (vbo)
            {
                bindVertexBufferObject(vbo);
                vad->enable_and_dispatch(state, new_array, vbo);
            }
            else
            {
                unbindVertexBufferObject();
                vad->enable_and_dispatch(state, new_array);
            }
        }
        else if (new_array!=vad->array || new_array->getModifiedCount()!=vad->modifiedCount)
        {
            GLBufferObject* vbo = isVertexBufferObjectSupported() ? new_array->getOrCreateGLBufferObject(state.getContextID()) : 0;
            if (vbo)
            {
                bindVertexBufferObject(vbo);
                vad->dispatch(state, new_array, vbo);
            }
            else
            {
                unbindVertexBufferObject();
                vad->dispatch(state, new_array);
            }
        }

        vad->array = new_array;
        vad->modifiedCount = new_array->getModifiedCount();

    }
    else if (vad->array)
    {
        disable(vad, state);
    }
}

void Shader::compileShader( osg::State& state ) const
{
    PerContextShader* pcs = getPCS( state.getContextID() );
    if( pcs ) pcs->compileShader( state );
}

void 
SparseTexture2DArray::apply( osg::State& state ) const
{
    // get the contextID (user defined ID of 0 upwards) for the 
    // current OpenGL context.
    const unsigned int contextID = state.getContextID();

    Texture::TextureObjectManager* tom = Texture::getTextureObjectManager(contextID).get();
    //ElapsedTime elapsedTime(&(tom->getApplyTime()));
    tom->getNumberApplied()++;

    const Extensions* extensions = getExtensions(contextID,true);

    // if not supported, then return
    if (!extensions->isTexture2DArraySupported() || !extensions->isTexture3DSupported())
    {
        OSG_WARN<<"Warning: Texture2DArray::apply(..) failed, 2D texture arrays are not support by OpenGL driver."<<std::endl;
        return;
    }

    // get the texture object for the current contextID.
    TextureObject* textureObject = getTextureObject(contextID);

    if (textureObject && _textureDepth>0)
    {
        const osg::Image* image = firstValidImage();
        if (image && getModifiedCount(0, contextID) != image->getModifiedCount())
        {
            // compute the internal texture format, this set the _internalFormat to an appropriate value.
            computeInternalFormat();

            GLsizei new_width, new_height, new_numMipmapLevels;

            // compute the dimensions of the texture.
            computeRequiredTextureDimensions(state, *image, new_width, new_height, new_numMipmapLevels);

            if (!textureObject->match(GL_TEXTURE_2D_ARRAY_EXT, new_numMipmapLevels, _internalFormat, new_width, new_height, 1, _borderWidth))
            {
                Texture::releaseTextureObject(contextID, _textureObjectBuffer[contextID].get());
                _textureObjectBuffer[contextID] = 0;
                textureObject = 0;
            }
        }
    }

    // if we already have an texture object, then 
    if (textureObject)
    {
        // bind texture object
        textureObject->bind();

        // if texture parameters changed, then reset them
        if (getTextureParameterDirty(state.getContextID())) applyTexParameters(GL_TEXTURE_2D_ARRAY_EXT,state);

        // if subload is specified, then use it to subload the images to GPU memory
        //if (_subloadCallback.valid())
        //{
        //    _subloadCallback->subload(*this,state);
        //}
        //else
        {
            // for each image of the texture array do
            for (GLsizei n=0; n < _textureDepth; n++)
            {
                osg::Image* image = _images[n].get();

                // if image content is modified, then upload it to the GPU memory
                // GW: this means we have to "dirty" an image before setting it!
                if (image && getModifiedCount(n,contextID) != image->getModifiedCount())
                {
                    applyTexImage2DArray_subload(state, image, _textureWidth, _textureHeight, n, _internalFormat, _numMipmapLevels);
                    getModifiedCount(n,contextID) = image->getModifiedCount();
                }
            }
        }
    }

    // nothing before, but we have valid images, so do manual upload and create texture object manually
    else if ( firstValidImage() != 0L ) // if (imagesValid())
    {
        // compute the internal texture format, this set the _internalFormat to an appropriate value.
        computeInternalFormat();

        // compute the dimensions of the texture.
        osg::Image* firstImage = firstValidImage();
        computeRequiredTextureDimensions(state, *firstImage, _textureWidth, _textureHeight, _numMipmapLevels);

        // create texture object
        textureObject = generateTextureObject(
            this, contextID,GL_TEXTURE_2D_ARRAY_EXT,_numMipmapLevels,_internalFormat,_textureWidth,_textureHeight,_textureDepth,0);

        // bind texture
        textureObject->bind();
        applyTexParameters(GL_TEXTURE_2D_ARRAY_EXT, state);

        _textureObjectBuffer[contextID] = textureObject;

        // First we need to allocate the texture memory
        int sourceFormat = _sourceFormat ? _sourceFormat : _internalFormat;

//.........这里部分代码省略.........

void
MPGeometry::renderPrimitiveSets(osg::State& state,
                                bool        usingVBOs) const
{
    // check the map frame to see if it's up to date
    if ( _frame.needsSync() )
    {
        // this lock protects a MapFrame sync when we have multiple DRAW threads.
        Threading::ScopedMutexLock exclusive( _frameSyncMutex );

        if ( _frame.needsSync() && _frame.sync() ) // always double check
        {
            // This should only happen is the layer ordering changes;
            // If layers are added or removed, the Tile gets rebuilt and
            // the point is moot.
            std::vector<Layer> reordered;
            const ImageLayerVector& layers = _frame.imageLayers();
            reordered.reserve( layers.size() );
            for( ImageLayerVector::const_iterator i = layers.begin(); i != layers.end(); ++i )
            {
                std::vector<Layer>::iterator j = std::find( _layers.begin(), _layers.end(), i->get()->getUID() );
                if ( j != _layers.end() )
                    reordered.push_back( *j );
            }
            _layers.swap( reordered );
        }
    }

    unsigned layersDrawn = 0;


    // access the GL extensions interface for the current GC:
    osg::ref_ptr<osg::GL2Extensions> ext = osg::GL2Extensions::Get( state.getContextID(), true );
    const osg::Program::PerContextProgram* pcp = state.getLastAppliedProgramObject();

    // cannot store these in the object since there could be multiple GCs (and multiple
    // PerContextPrograms) at large
    GLint tileKeyLocation;
    GLint opacityLocation;
    GLint uidLocation;
    GLint orderLocation;
    GLint texMatParentLocation;

    // The PCP can change (especially in a VirtualProgram environment). So we do need to
    // requery the uni locations each time unfortunately. TODO: explore optimizations.
    if ( pcp )
    {
        tileKeyLocation      = pcp->getUniformLocation( _tileKeyUniformNameID );
        opacityLocation      = pcp->getUniformLocation( _opacityUniformNameID );
        uidLocation          = pcp->getUniformLocation( _uidUniformNameID );
        orderLocation        = pcp->getUniformLocation( _orderUniformNameID );
        texMatParentLocation = pcp->getUniformLocation( _texMatParentUniformNameID );
    }
    
    // apply the tilekey uniform once.
    ext->glUniform4fv( tileKeyLocation, 1, _tileKeyValue.ptr() );

    // activate the tile coordinate set - same for all layers
    state.setTexCoordPointer( _imageUnit+1, _tileCoords.get() );

    if ( _layers.size() > 0 )
    {
        float prev_opacity        = -1.0f;
        float prev_alphaThreshold = -1.0f;

        // first bind any shared layers
        // TODO: optimize by pre-storing shared indexes
        for(unsigned i=0; i<_layers.size(); ++i)
        {
            const Layer& layer = _layers[i];

            // a "shared" layer binds to a secondary texture unit so that other layers
            // can see it and use it.
            if ( layer._imageLayer->isShared() )
            {
                int sharedUnit = layer._imageLayer->shareImageUnit().get();
                {
                    state.setActiveTextureUnit( sharedUnit );
                    state.setTexCoordPointer( sharedUnit, layer._texCoords.get() );
                    // bind the texture for this layer to the active share unit.
                    layer._tex->apply( state );

                    // no texture LOD blending for shared layers for now. maybe later.
                }
            }
        }

        // track the active image unit.
        int activeImageUnit = -1;

        // interate over all the image layers
        //glDepthMask(GL_TRUE);
        for(unsigned i=0; i<_layers.size(); ++i)
        {
          //  if ( i > 0 )
            //    glDepthMask(GL_FALSE);

            const Layer& layer = _layers[i];

            if ( layer._imageLayer->getVisible() )
//.........这里部分代码省略.........

void
VirtualProgram::apply( osg::State& state ) const
{
    if (_shaderMap.empty() && !_inheritSet)
    {
        // If there's no data in the VP, and never has been, unload any existing program.
        // NOTE: OSG's State processor creates a "global default attribute" for each type.
        // Sine we have no way of knowing whether the user created the VP or OSG created it
        // as the default fallback, we use the "_inheritSet" flag to differeniate. This
        // prevents any shader leakage from a VP-enabled node.
        const unsigned int contextID = state.getContextID();
        const osg::GL2Extensions* extensions = osg::GL2Extensions::Get(contextID,true);
        if( ! extensions->isGlslSupported() ) return;

        extensions->glUseProgram( 0 );
        state.setLastAppliedProgramObject(0);
        return;
    }

    // first, find and collect all the VirtualProgram attributes:
    ShaderMap         accumShaderMap;
    AttribBindingList accumAttribBindings;
    AttribAliasMap    accumAttribAliases;
    
    // Build the active shader map up to this point:
    if ( _inherit )
    {
        accumulateShaders(state, _mask, accumShaderMap, accumAttribBindings, accumAttribAliases);
    }

    // next add the local shader components to the map, respecting the override values:
    {
        Threading::ScopedReadLock readonly(_dataModelMutex);

        for( ShaderMap::const_iterator i = _shaderMap.begin(); i != _shaderMap.end(); ++i )
        {
            if ( i->second.accept(state) )
            {
                addToAccumulatedMap( accumShaderMap, i->first, i->second );
            }
        }

        const AttribBindingList& abl = this->getAttribBindingList();
        accumAttribBindings.insert( abl.begin(), abl.end() );

#ifdef USE_ATTRIB_ALIASES
        const AttribAliasMap& aliases = this->getAttribAliases();
        accumAttribAliases.insert( aliases.begin(), aliases.end() );
#endif
    }


    // next, assemble a list of the shaders in the map so we can use it as our
    // program cache key.
    // (Note: at present, the "cache key" does not include any information on the vertex
    // attribute bindings. Technically it should, but in practice this might not be an
    // issue; it is unlikely one would have two identical shader programs with different
    // bindings.)
    ShaderVector vec;
    vec.reserve( accumShaderMap.size() );
    for( ShaderMap::iterator i = accumShaderMap.begin(); i != accumShaderMap.end(); ++i )
    {
        ShaderEntry& entry = i->second;
        if ( i->second.accept(state) )
        {
            vec.push_back( entry._shader.get() );
        }
    }

    // see if there's already a program associated with this list:
    osg::ref_ptr<osg::Program> program;

    // look up the program:
    {
        Threading::ScopedReadLock shared( _programCacheMutex );

        ProgramMap::const_iterator p = _programCache.find( vec );
        if ( p != _programCache.end() )
        {
            program = p->second.get();
        }
    }

    // if not found, lock and build it:
    if ( !program.valid() )
    {
        // build a new set of accumulated functions, to support the creation of main()
        ShaderComp::FunctionLocationMap accumFunctions;
        accumulateFunctions( state, accumFunctions );

        // now double-check the program cache, and failing that, build the
        // new shader Program.
        {
            Threading::ScopedWriteLock exclusive( _programCacheMutex );

            // double-check: look again ito negate race conditions
            ProgramMap::const_iterator p = _programCache.find( vec );
            if ( p != _programCache.end() )
            {
                program = p->second.get();
//.........这里部分代码省略.........

void
VirtualProgram::apply( osg::State& state ) const
{
    if (_shaderMap.empty() && !_inheritSet)
    {
        // If there's no data in the VP, and never has been, unload any existing program.
        // NOTE: OSG's State processor creates a "global default attribute" for each type.
        // Sine we have no way of knowing whether the user created the VP or OSG created it
        // as the default fallback, we use the "_inheritSet" flag to differeniate. This
        // prevents any shader leakage from a VP-enabled node.
        const unsigned int contextID = state.getContextID();
        const osg::GL2Extensions* extensions = osg::GL2Extensions::Get(contextID,true);
        if( ! extensions->isGlslSupported() ) return;

        extensions->glUseProgram( 0 );
        state.setLastAppliedProgramObject(0);
        return;
    }

    // first, find and collect all the VirtualProgram attributes:
    ShaderMap         accumShaderMap;
    AttribBindingList accumAttribBindings;
    AttribAliasMap    accumAttribAliases;
    
    if ( _inherit )
    {
        const StateHack::AttributeVec* av = StateHack::GetAttributeVec( state, this );
        if ( av && av->size() > 0 )
        {
            // find the deepest VP that doesn't inherit:
            unsigned start = 0;
            for( start = (int)av->size()-1; start > 0; --start )
            {
                const VirtualProgram* vp = dynamic_cast<const VirtualProgram*>( (*av)[start].first );
                if ( vp && (vp->_mask & _mask) && vp->_inherit == false )
                    break;
            }
            
            // collect shaders from there to here:
            for( unsigned i=start; i<av->size(); ++i )
            {
                const VirtualProgram* vp = dynamic_cast<const VirtualProgram*>( (*av)[i].first );
                if ( vp && (vp->_mask && _mask) )
                {
                    ShaderMap vpShaderMap;
                    vp->getShaderMap( vpShaderMap );

                    for( ShaderMap::const_iterator i = vpShaderMap.begin(); i != vpShaderMap.end(); ++i )
                    {
                        addToAccumulatedMap( accumShaderMap, i->first, i->second );
                    }

                    const AttribBindingList& abl = vp->getAttribBindingList();
                    accumAttribBindings.insert( abl.begin(), abl.end() );

#ifdef USE_ATTRIB_ALIASES
                    const AttribAliasMap& aliases = vp->getAttribAliases();
                    accumAttribAliases.insert( aliases.begin(), aliases.end() );
#endif
                }
            }
        }
    }

    // next add the local shader components to the map, respecting the override values:
    {
        Threading::ScopedReadLock readonly(_dataModelMutex);

        for( ShaderMap::const_iterator i = _shaderMap.begin(); i != _shaderMap.end(); ++i )
        {
            addToAccumulatedMap( accumShaderMap, i->first, i->second );
        }

        const AttribBindingList& abl = this->getAttribBindingList();
        accumAttribBindings.insert( abl.begin(), abl.end() );

#ifdef USE_ATTRIB_ALIASES
        const AttribAliasMap& aliases = this->getAttribAliases();
        accumAttribAliases.insert( aliases.begin(), aliases.end() );
#endif
    }


    if ( true ) //even with nothing in the map, we still want mains! -gw  //accumShaderMap.size() )
    {
        // next, assemble a list of the shaders in the map so we can use it as our
        // program cache key.
        // (Note: at present, the "cache key" does not include any information on the vertex
        // attribute bindings. Technically it should, but in practice this might not be an
        // issue; it is unlikely one would have two identical shader programs with different
        // bindings.)
        ShaderVector vec;
        vec.reserve( accumShaderMap.size() );
        for( ShaderMap::iterator i = accumShaderMap.begin(); i != accumShaderMap.end(); ++i )
        {
            ShaderEntry& entry = i->second;
            vec.push_back( entry.first.get() );
        }
        
        // see if there's already a program associated with this list:
//.........这里部分代码省略.........

void
MPGeometry::renderPrimitiveSets(osg::State& state,
                                bool        usingVBOs) const
{
    // check the map frame to see if it's up to date
    if ( _frame.needsSync() )
    {
        // this lock protects a MapFrame sync when we have multiple DRAW threads.
        Threading::ScopedMutexLock exclusive( _frameSyncMutex );

        if ( _frame.needsSync() && _frame.sync() ) // always double check
        {
            // This should only happen is the layer ordering changes;
            // If layers are added or removed, the Tile gets rebuilt and
            // the point is moot.
            std::vector<Layer> reordered;
            const ImageLayerVector& layers = _frame.imageLayers();
            reordered.reserve( layers.size() );
            for( ImageLayerVector::const_iterator i = layers.begin(); i != layers.end(); ++i )
            {
                std::vector<Layer>::iterator j = std::find( _layers.begin(), _layers.end(), i->get()->getUID() );
                if ( j != _layers.end() )
                    reordered.push_back( *j );
            }
            _layers.swap( reordered );
        }
    }

    unsigned layersDrawn = 0;


    osg::ref_ptr<osg::GL2Extensions> ext = osg::GL2Extensions::Get( state.getContextID(), true );
    const osg::Program::PerContextProgram* pcp = state.getLastAppliedProgramObject();

    GLint opacityLocation;
    GLint uidLocation;
    GLint orderLocation;
    GLint texMatParentLocation;

    // yes, it's possible that the PCP is not set up yet.
    // TODO: can we optimize this so we don't need to get uni locations every time?
    if ( pcp )
    {
        opacityLocation      = pcp->getUniformLocation( _opacityUniform->getNameID() );
        uidLocation          = pcp->getUniformLocation( _layerUIDUniform->getNameID() );
        orderLocation        = pcp->getUniformLocation( _layerOrderUniform->getNameID() );
        texMatParentLocation = pcp->getUniformLocation( _texMatParentUniform->getNameID() );
    }

    // activate the tile coordinate set - same for all layers
    state.setTexCoordPointer( _imageUnit+1, _tileCoords.get() );

    if ( _layers.size() > 0 )
    {
        float prev_opacity        = -1.0f;
        float prev_alphaThreshold = -1.0f;

        // first bind any shared layers
        // TODO: optimize by pre-storing shared indexes
        for(unsigned i=0; i<_layers.size(); ++i)
        {
            const Layer& layer = _layers[i];

            // a "shared" layer binds to a secondary texture unit so that other layers
            // can see it and use it.
            if ( layer._imageLayer->isShared() )
            {
                int sharedUnit = layer._imageLayer->shareImageUnit().get();
                {
                    state.setActiveTextureUnit( sharedUnit );
                    state.setTexCoordPointer( sharedUnit, layer._texCoords.get() );
                    // bind the texture for this layer to the active share unit.
                    layer._tex->apply( state );

                    // no texture LOD blending for shared layers for now. maybe later.
                }
            }
        }

        // track the active image unit.
        int activeImageUnit = -1;

        // interate over all the image layers
        for(unsigned i=0; i<_layers.size(); ++i)
        {
            const Layer& layer = _layers[i];

            if ( layer._imageLayer->getVisible() )
            {
                // activate the visible unit if necessary:
                if ( activeImageUnit != _imageUnit )
                {
                    state.setActiveTextureUnit( _imageUnit );
                    activeImageUnit = _imageUnit;
                }

                // bind the texture for this layer:
                layer._tex->apply( state );

                // if we're using a parent texture for blending, activate that now
//.........这里部分代码省略.........

void
MPGeometry::renderPrimitiveSets(osg::State& state,
                                bool        renderColor,
                                bool        usingVBOs) const
{
    // check the map frame to see if it's up to date
    if ( _frame.needsSync() )
    {
        // this lock protects a MapFrame sync when we have multiple DRAW threads.
        Threading::ScopedMutexLock exclusive( _frameSyncMutex );

        if ( _frame.needsSync() && _frame.sync() ) // always double check
        {
            // This should only happen is the layer ordering changes;
            // If layers are added or removed, the Tile gets rebuilt and
            // the point is moot.
            std::vector<Layer> reordered;
            const ImageLayerVector& layers = _frame.imageLayers();
            reordered.reserve( layers.size() );
            for( ImageLayerVector::const_iterator i = layers.begin(); i != layers.end(); ++i )
            {
                std::vector<Layer>::iterator j = std::find( _layers.begin(), _layers.end(), i->get()->getUID() );
                if ( j != _layers.end() )
                    reordered.push_back( *j );
            }
            _layers.swap( reordered );
        }
    }

    unsigned layersDrawn = 0;

    // access the GL extensions interface for the current GC:
    const osg::Program::PerContextProgram* pcp = 0L;

#if OSG_MIN_VERSION_REQUIRED(3,3,3)
	osg::ref_ptr<osg::GLExtensions> ext;
#else
    osg::ref_ptr<osg::GL2Extensions> ext;
#endif
    unsigned contextID;

    if (_supportsGLSL)
    {
        contextID = state.getContextID();
#if OSG_MIN_VERSION_REQUIRED(3,3,3)
		ext = osg::GLExtensions::Get(contextID, true);
#else
		ext = osg::GL2Extensions::Get( contextID, true );
#endif
        pcp = state.getLastAppliedProgramObject();
    }

    // cannot store these in the object since there could be multiple GCs (and multiple
    // PerContextPrograms) at large
    GLint tileKeyLocation       = -1;
    GLint birthTimeLocation     = -1;
    GLint opacityLocation       = -1;
    GLint uidLocation           = -1;
    GLint orderLocation         = -1;
    GLint texMatParentLocation  = -1;
    GLint minRangeLocation      = -1;
    GLint maxRangeLocation      = -1;

    // The PCP can change (especially in a VirtualProgram environment). So we do need to
    // requery the uni locations each time unfortunately. TODO: explore optimizations.
    if ( pcp )
    {
        tileKeyLocation      = pcp->getUniformLocation( _tileKeyUniformNameID );
        birthTimeLocation    = pcp->getUniformLocation( _birthTimeUniformNameID );
        opacityLocation      = pcp->getUniformLocation( _opacityUniformNameID );
        uidLocation          = pcp->getUniformLocation( _uidUniformNameID );
        orderLocation        = pcp->getUniformLocation( _orderUniformNameID );
        texMatParentLocation = pcp->getUniformLocation( _texMatParentUniformNameID );
        minRangeLocation = pcp->getUniformLocation( _minRangeUniformNameID );
        maxRangeLocation = pcp->getUniformLocation( _maxRangeUniformNameID );
    }
    
    // apply the tilekey uniform once.
    if ( tileKeyLocation >= 0 )
    {
        ext->glUniform4fv( tileKeyLocation, 1, _tileKeyValue.ptr() );
    }

    // set the "birth time" - i.e. the time this tile last entered the scene in the current GC.
    if ( birthTimeLocation >= 0 )
    {
        PerContextData& pcd = _pcd[contextID];
        if ( pcd.birthTime < 0.0f )
        {
            const osg::FrameStamp* stamp = state.getFrameStamp();
            if ( stamp )
            {
                pcd.birthTime = stamp->getReferenceTime();
            }
        }
        ext->glUniform1f( birthTimeLocation, pcd.birthTime );
    }

    // activate the tile coordinate set - same for all layers
    if ( renderColor )
//.........这里部分代码省略.........