layercache.cpp

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/***************************************************************************
 *   Copyright (C) 2005-2013 by the FIFE team                              *
 *   http://www.fifengine.net                                              *
 *   This file is part of FIFE.                                            *
 *                                                                         *
 *   FIFE 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 2.1 of the License, or (at your option) any later version.    *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this library; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA          *
 ***************************************************************************/

// Standard C++ library includes
#include <cfloat>

// 3rd party library includes

// FIFE includes
// These includes are split up in two parts, separated by one empty line
// First block: files included from the FIFE root src directory
// Second block: files included from the same folder

#include "model/metamodel/grids/cellgrid.h"
#include "model/metamodel/action.h"
#include "model/structures/layer.h"
#include "model/structures/instance.h"
#include "model/structures/location.h"
#include "util/base/exception.h"
#include "util/log/logger.h"
#include "util/math/fife_math.h"
#include "util/math/angles.h"
#include "video/renderbackend.h"
#include "video/image.h"
#include "video/animation.h"
#include "video/imagemanager.h"

#include "camera.h"
#include "layercache.h"
#include "visual.h"


namespace FIFE {
    static Logger _log(LM_CAMERA);
    
    class CacheLayerChangeListener : public LayerChangeListener {
    public:
        CacheLayerChangeListener(LayerCache* cache) {
            m_cache = cache;
        }
        virtual ~CacheLayerChangeListener() {};

        virtual void onLayerChanged(Layer* layer, std::vector<Instance*>& instances) {
            for(std::vector<Instance*>::iterator i = instances.begin();
                i != instances.end(); ++i) {
                m_cache->updateInstance(*i);
            }
        }

        virtual void onInstanceCreate(Layer* layer, Instance* instance) {
            m_cache->addInstance(instance);
        }

        virtual void onInstanceDelete(Layer* layer, Instance* instance) {
            m_cache->removeInstance(instance);
        }
    private:
        LayerCache* m_cache;
    };

    // used screenpoint z for sorting, calculated from camera
    class InstanceDistanceSortCamera {
    public:
        inline bool operator()(RenderItem* const & lhs, RenderItem* const & rhs) {
            if (Mathd::Equal(lhs->screenpoint.z, rhs->screenpoint.z)) {
                InstanceVisual* liv = lhs->instance->getVisual<InstanceVisual>();
                InstanceVisual* riv = rhs->instance->getVisual<InstanceVisual>();
                return liv->getStackPosition() < riv->getStackPosition();
            }
            return lhs->screenpoint.z < rhs->screenpoint.z;
        }
    };
    // used instance location and camera rotation for sorting
    class InstanceDistanceSortLocation {
    public:
        InstanceDistanceSortLocation(double rotation) {
            if ((rotation >= 0) && (rotation <= 60)) { // 30 deg
                xtox = 0;
                xtoy = -1;
                ytox = 1;
                ytoy = 0.5;
            } else if ((rotation >= 60) && (rotation <= 120)) { // 90 deg
                xtox = -1;
                xtoy = -1;
                ytox = 0.5;
                ytoy = -0.5;
            } else if ((rotation >= 120) && (rotation <= 180)) { // 150 deg
                xtox = 0;
                xtoy = -1;
                ytox = -1;
                ytoy = -0.5;
            } else if ((rotation >= 180) && (rotation <= 240)) { // 210 deg
                xtox = 0;
                xtoy = 1;
                ytox = -1;
                ytoy = -0.5;
            } else if ((rotation >= 240) && (rotation <= 300)) { // 270 deg
                xtox = 1;
                xtoy = 1;
                ytox = -0.5;
                ytoy = 0.5;
            } else if ((rotation >= 300) && (rotation <= 360)) { // 330 deg
                xtox = 0;
                xtoy = 1;
                ytox = 1;
                ytoy = 0.5;
            }
        }

        inline bool operator()(RenderItem* const & lhs, RenderItem* const & rhs) {
            ExactModelCoordinate lpos = lhs->instance->getLocationRef().getExactLayerCoordinates();
            ExactModelCoordinate rpos = rhs->instance->getLocationRef().getExactLayerCoordinates();
            lpos.x += lpos.y / 2;
            rpos.x += rpos.y / 2;
            InstanceVisual* liv = lhs->instance->getVisual<InstanceVisual>();
            InstanceVisual* riv = rhs->instance->getVisual<InstanceVisual>();
            int32_t lvc = ceil(xtox*lpos.x + ytox*lpos.y) + ceil(xtoy*lpos.x + ytoy*lpos.y) + liv->getStackPosition();
            int32_t rvc = ceil(xtox*rpos.x + ytox*rpos.y) + ceil(xtoy*rpos.x + ytoy*rpos.y) + riv->getStackPosition();
            if (lvc == rvc) {
                if (Mathd::Equal(lpos.z, rpos.z)) {
                    return liv->getStackPosition() < riv->getStackPosition();
                }
                return lpos.z < rpos.z;
            }
            return lvc < rvc;
        }
    private:
        double xtox;
        double xtoy;
        double ytox;
        double ytoy;
    };
    // used screenpoint z for sorting and as fallback first the instance location z and then the stack position
    class InstanceDistanceSortCameraAndLocation {
    public:
        inline bool operator()(RenderItem* const & lhs, RenderItem* const & rhs) {
            if (Mathd::Equal(lhs->screenpoint.z, rhs->screenpoint.z)) {
                const ExactModelCoordinate& lpos = lhs->instance->getLocationRef().getExactLayerCoordinatesRef();
                const ExactModelCoordinate& rpos = rhs->instance->getLocationRef().getExactLayerCoordinatesRef();
                if (Mathd::Equal(lpos.z, rpos.z)) {
                    InstanceVisual* liv = lhs->instance->getVisual<InstanceVisual>();
                    InstanceVisual* riv = rhs->instance->getVisual<InstanceVisual>();
                    return liv->getStackPosition() < riv->getStackPosition();
                }
                return lpos.z < rpos.z;
            }
            return lhs->screenpoint.z < rhs->screenpoint.z;
        }
    };

    LayerCache::LayerCache(Camera* camera) {
        m_camera = camera;
        m_layer = 0;
        m_layerObserver = 0;
        m_tree = 0;
        m_zMin = 0.0;
        m_zMax = 0.0;
        m_zoom = camera->getZoom();
        m_zoomed = !Mathd::Equal(m_zoom, 1.0);
        m_straightZoom = Mathd::Equal(fmod(m_zoom, 1.0), 0.0);
        
        if(RenderBackend::instance()->getName() == "OpenGL" && RenderBackend::instance()->isDepthBufferEnabled()) {
            m_needSorting = false;
        } else {
            m_needSorting = true;
        }
    }

    LayerCache::~LayerCache() {
        // removes all Entries
        for (std::vector<Entry*>::iterator it = m_entries.begin(); it != m_entries.end(); ++it) {
            delete *it;
        }
        // removes all RenderItems
        for (std::vector<RenderItem*>::iterator it = m_renderItems.begin(); it != m_renderItems.end(); ++it) {
            delete *it;
        }
        m_layer->removeChangeListener(m_layerObserver);
        delete m_layerObserver;
        delete m_tree;
    }

    void LayerCache::setLayer(Layer* layer) {
        if (m_layer != layer) {
            if (m_layer) {
                m_layer->removeChangeListener(m_layerObserver);
                delete m_layerObserver;
            }
            m_layer = layer;
            m_layerObserver = new CacheLayerChangeListener(this);
            layer->addChangeListener(m_layerObserver);
            reset();
        }
    }

    void LayerCache::reset() {
        // removes all Entries
        for (std::vector<Entry*>::iterator it = m_entries.begin(); it != m_entries.end(); ++it) {
            delete *it;
        }
        m_entries.clear();
        // removes all RenderItems
        for (std::vector<RenderItem*>::iterator it = m_renderItems.begin(); it != m_renderItems.end(); ++it) {
            delete *it;
        }
        m_renderItems.clear();
        m_instance_map.clear();
        m_entriesToUpdate.clear();
        m_freeEntries.clear();
        m_cacheImage.reset();

        delete m_tree;
        m_tree = new CacheTree;
        const std::vector<Instance*>& instances = m_layer->getInstances();
        for(std::vector<Instance*>::const_iterator i = instances.begin();
            i != instances.end(); ++i) {
            addInstance(*i);
        }
    }

    void LayerCache::addInstance(Instance* instance) {
        assert(m_instance_map.find(instance) == m_instance_map.end());

        RenderItem* item;
        Entry* entry;
        if (m_freeEntries.empty()) {
            // creates new RenderItem
            item = new RenderItem(instance);
            m_renderItems.push_back(item);
            m_instance_map[instance] = m_renderItems.size() - 1;
            // creates new Entry
            entry = new Entry();
            m_entries.push_back(entry);
            entry->instanceIndex = m_renderItems.size() - 1;
            entry->entryIndex = m_entries.size() - 1;
        } else {
            // uses free/unused RenderItem
            int32_t index = m_freeEntries.front();
            m_freeEntries.pop_front();
            item = m_renderItems[index];
            item->instance = instance;
            m_instance_map[instance] = index;
            // uses free/unused Entry
            entry = m_entries[index];
            entry->instanceIndex = index;
            entry->entryIndex = index;
        }

        entry->node = 0;
        entry->forceUpdate = true;
        entry->visible = true;
        entry->updateInfo = EntryFullUpdate;

        m_entriesToUpdate.insert(entry->entryIndex);
    }

    void LayerCache::removeInstance(Instance* instance) {
        assert(m_instance_map.find(instance) != m_instance_map.end());

        Entry* entry = m_entries[m_instance_map[instance]];
        assert(entry->instanceIndex == m_instance_map[instance]);
        RenderItem* item = m_renderItems[entry->instanceIndex];
        // removes entry from updates
        std::set<int32_t>::iterator it = m_entriesToUpdate.find(entry->entryIndex);
        if (it != m_entriesToUpdate.end()) {
            m_entriesToUpdate.erase(it);
        }
        // removes entry from CacheTree
        if (entry->node) {
            entry->node->data().erase(entry->entryIndex);
            entry->node = 0;
        }
        entry->instanceIndex = -1;
        entry->forceUpdate = false;
        m_instance_map.erase(instance);

        // removes instance from RenderList
        RenderList& renderList = m_camera->getRenderListRef(m_layer);
        for (RenderList::iterator it = renderList.begin(); it != renderList.end(); ++it) {
            if ((*it)->instance == instance) {
                renderList.erase(it);
                break;
            }
        }
        // resets RenderItem
        item->reset();
        // adds free entry
        m_freeEntries.push_back(entry->entryIndex);
    }

    void LayerCache::updateInstance(Instance* instance) {
        Entry* entry = m_entries[m_instance_map[instance]];
        if (entry->instanceIndex == -1) {
            return;
        }

        // convert necessary instance update flags to entry update flags
        const InstanceChangeInfo ici = instance->getChangeInfo();
        if ((ici & ICHANGE_LOC) == ICHANGE_LOC) {
            entry->updateInfo |= EntryPositionUpdate;
        }
        if ((ici & ICHANGE_ROTATION) == ICHANGE_ROTATION ||
            (ici & ICHANGE_ACTION) == ICHANGE_ACTION ||
            (ici & ICHANGE_TRANSPARENCY) == ICHANGE_TRANSPARENCY ||
            (ici & ICHANGE_VISIBLE) == ICHANGE_VISIBLE ||
            (ici & ICHANGE_VISUAL) == ICHANGE_VISUAL) {
            entry->updateInfo |= EntryVisualUpdate;
        }

        // if entry is not already inserted
        if (!entry->forceUpdate && entry->updateInfo != EntryNoneUpdate) {
            entry->forceUpdate = true;
            m_entriesToUpdate.insert(entry->entryIndex);
        }
    }

    class CacheTreeCollector {
            std::vector<int32_t>& m_indices;
            Rect m_viewport;
        public:
            CacheTreeCollector(std::vector<int32_t>& indices, const Rect& viewport)
            : m_indices(indices), m_viewport(viewport) {
            }
            bool visit(LayerCache::CacheTree::Node* node, int32_t d = -1);
    };

    bool CacheTreeCollector::visit(LayerCache::CacheTree::Node* node, int32_t d) {
        if(!m_viewport.intersects(Rect(node->x(), node->y(),node->size(),node->size()))) {
            return false;
        }
        m_indices.insert(m_indices.end(), node->data().begin(), node->data().end());
        return true;
    }

    void LayerCache::collect(const Rect& viewport, std::vector<int32_t>& index_list) {
        CacheTree::Node * node = m_tree->find_container(viewport);
        CacheTreeCollector collector(index_list, viewport);
        node->apply_visitor(collector);
        node = node->parent();
        while(node) {
            collector.visit(node);
            node = node->parent();
        }
    }

    void LayerCache::update(Camera::Transform transform, RenderList& renderlist) {
        // this is only a bit faster, but works without this block too.
        if(!m_layer->areInstancesVisible()) {
            FL_DBG(_log, "Layer instances hidden");
            std::set<int32_t>::const_iterator entry_it = m_entriesToUpdate.begin();
            for (; entry_it != m_entriesToUpdate.end(); ++entry_it) {
                Entry* entry = m_entries[*entry_it];
                entry->forceUpdate = false;
                entry->visible = false;
            }
            m_entriesToUpdate.clear();
            renderlist.clear();
            return;
        }
        // if transform is none then we have only to update the instances with an update info.
        if (transform == Camera::NoneTransform) {
            if (!m_entriesToUpdate.empty()) {
                std::set<int32_t> entryToRemove;
                updateEntries(entryToRemove, renderlist);
                //std::cout << "update entries: " << int32_t(m_entriesToUpdate.size()) << " remove entries: " << int32_t(entryToRemove.size()) <<"\n";
                if (!entryToRemove.empty()) {
                    std::set<int32_t>::iterator entry_it = entryToRemove.begin();
                    for (; entry_it != entryToRemove.end(); ++entry_it) {
                        m_entriesToUpdate.erase(*entry_it);
                    }
                }
            }
        } else {
            m_zoom = m_camera->getZoom();
            m_zoomed = !Mathd::Equal(m_zoom, 1.0);
            m_straightZoom = Mathd::Equal(fmod(m_zoom, 1.0), 0.0);
            // clear old renderlist
            renderlist.clear();
            // update all entries
            if ((transform & Camera::RotationTransform) == Camera::RotationTransform ||
                (transform & Camera::TiltTransform) == Camera::TiltTransform ||
                (transform & Camera::ZTransform) == Camera::ZTransform) {
                fullUpdate(transform);
            } else {
                fullCoordinateUpdate(transform);
            }

            // create viewport coordinates to collect entries
            Rect viewport = m_camera->getViewPort();
            Rect screenViewport = viewport;
            DoublePoint3D viewport_a = m_camera->screenToVirtualScreen(Point3D(viewport.x, viewport.y));
            DoublePoint3D viewport_b = m_camera->screenToVirtualScreen(Point3D(viewport.right(), viewport.bottom()));
            viewport.x = static_cast<int32_t>(std::min(viewport_a.x, viewport_b.x));
            viewport.y = static_cast<int32_t>(std::min(viewport_a.y, viewport_b.y));
            viewport.w = static_cast<int32_t>(std::max(viewport_a.x, viewport_b.x) - viewport.x);
            viewport.h = static_cast<int32_t>(std::max(viewport_a.y, viewport_b.y) - viewport.y);
            m_zMin = 0.0;
            m_zMax = 0.0;

            // FL_LOG(_log, LMsg("camera-update viewport") << viewport);
            std::vector<int32_t> index_list;
            collect(viewport, index_list);
            // fill renderlist
            for (uint32_t i = 0; i != index_list.size(); ++i) {
                Entry* entry = m_entries[index_list[i]];
                RenderItem* item = m_renderItems[entry->instanceIndex];
                if (!item->image || !entry->visible) {
                    continue;
                }

                if (item->dimensions.intersects(screenViewport)) {
                    renderlist.push_back(item);
                }
            }

            if (m_needSorting) {
                sortRenderList(renderlist);
            } else {
                // calculates zmin and zmax of the current viewport
                Rect r = m_camera->getMapViewPort();
                std::vector<ExactModelCoordinate> coords;
                coords.push_back(ExactModelCoordinate(r.x, r.y));
                coords.push_back(ExactModelCoordinate(r.x, r.y+r.h));
                coords.push_back(ExactModelCoordinate(r.x+r.w, r.y));
                coords.push_back(ExactModelCoordinate(r.x+r.w, r.y+r.h));
                for (uint8_t i = 0; i < 4; ++i) {
                    double z = m_camera->toVirtualScreenCoordinates(coords[i]).z;
                    m_zMin = std::min(z, m_zMin);
                    m_zMax = std::max(z, m_zMax);
                }

                sortRenderList(renderlist);
            }
        }
    }
    
    void LayerCache::fullUpdate(Camera::Transform transform) {
        bool rotationChange = (transform & Camera::RotationTransform) == Camera::RotationTransform;
        for (uint32_t i = 0; i != m_entries.size(); ++i) {
            Entry* entry = m_entries[i];
            if (entry->instanceIndex != -1) {
                if (rotationChange || entry->forceUpdate) {
                    bool force = entry->forceUpdate;
                    updateVisual(entry);
                    if (force && !entry->forceUpdate) {
                        // no action
                        entry->updateInfo = EntryNoneUpdate;
                        m_entriesToUpdate.erase(entry->entryIndex);
                    } else if (!force && entry->forceUpdate) {
                        // new action
                        entry->updateInfo |= EntryVisualUpdate;
                        m_entriesToUpdate.insert(entry->entryIndex);
                    }
                }
                updatePosition(entry);
            }
        }
    }

    void LayerCache::fullCoordinateUpdate(Camera::Transform transform) {
        bool zoomChange = (transform & Camera::ZoomTransform) == Camera::ZoomTransform;
        for (uint32_t i = 0; i != m_entries.size(); ++i) {
            Entry* entry = m_entries[i];
            if (entry->instanceIndex != -1) {
                if (entry->forceUpdate) {
                    updateVisual(entry);
                    updatePosition(entry);
                    if (!entry->forceUpdate) {
                        // no action
                        entry->updateInfo = EntryNoneUpdate;
                        m_entriesToUpdate.erase(entry->entryIndex);
                    }
                    continue;
                }
                updateScreenCoordinate(m_renderItems[entry->instanceIndex], zoomChange);
            }
        }
    }

    void LayerCache::updateEntries(std::set<int32_t>& removes, RenderList& renderlist) {
        RenderList needSorting;
        Rect viewport = m_camera->getViewPort();
        std::set<int32_t>::const_iterator entry_it = m_entriesToUpdate.begin();
        for (; entry_it != m_entriesToUpdate.end(); ++entry_it) {
            Entry* entry = m_entries[*entry_it];
            entry->forceUpdate = false;
            if (entry->instanceIndex == -1) {
                entry->updateInfo = EntryNoneUpdate;
                removes.insert(*entry_it);
                continue;
            }
            RenderItem* item = m_renderItems[entry->instanceIndex];
            bool onScreenA = entry->visible && item->image && item->dimensions.intersects(viewport);
            bool positionUpdate = (entry->updateInfo & EntryPositionUpdate) == EntryPositionUpdate;
            if ((entry->updateInfo & EntryVisualUpdate) == EntryVisualUpdate) {
                positionUpdate |= updateVisual(entry);
            }
            if (positionUpdate) {
                updatePosition(entry);
            }
            bool onScreenB = entry->visible && item->image && item->dimensions.intersects(viewport);
            if (onScreenA != onScreenB) {
                if (!onScreenA) {
                    // add to renderlist and sort
                    renderlist.push_back(item);
                    needSorting.push_back(item);
                } else {
                    // remove from renderlist
                    for (RenderList::iterator it = renderlist.begin(); it != renderlist.end(); ++it) {
                        if ((*it)->instance == item->instance) {
                            renderlist.erase(it);
                            break;
                        }
                    }
                }
            } else if (onScreenA && onScreenB && positionUpdate) {
                // sort
                needSorting.push_back(item);
            }

            if (!entry->forceUpdate) {
                entry->forceUpdate = false;
                entry->updateInfo = EntryNoneUpdate;
                removes.insert(*entry_it);
            } else {
                entry->updateInfo = EntryVisualUpdate;
            }
        }

        if (!needSorting.empty()) {
            if (m_needSorting) {
                sortRenderList(renderlist);
            } else {
                sortRenderList(needSorting);
            }
        }
    }

    bool LayerCache::updateVisual(Entry* entry) {
        RenderItem* item = m_renderItems[entry->instanceIndex];
        Instance* instance = item->instance;
        InstanceVisual* visual = instance->getVisual<InstanceVisual>();
        item->facingAngle = instance->getRotation();
        int32_t angle = static_cast<int32_t>(m_camera->getRotation()) + item->facingAngle;
        Action* action = instance->getCurrentAction();
        ImagePtr image;

        if (visual) {
            uint8_t layerTrans = m_layer->getLayerTransparency();
            uint8_t instanceTrans = visual->getTransparency();
            if (layerTrans != 0) {
                if (instanceTrans != 0) {
                    uint8_t calcTrans = layerTrans - instanceTrans;
                    if (calcTrans >= 0) {
                        instanceTrans = calcTrans;
                    } else {
                        instanceTrans = 0;
                    }
                } else {
                    instanceTrans = layerTrans;
                }
            }
            item->transparency = 255 - instanceTrans;
            // only visible if visual and layer are visible and item is not totally transparent
            entry->visible = (visual->isVisible() && item->transparency != 0) && m_layer->areInstancesVisible();
        }
        // delete old overlay
        item->deleteOverlayData();

        if (!action) {
            // Try static images then default action.
            int32_t image_id = item->getStaticImageIndexByAngle(angle, instance);
            if (image_id == -1) {
                if (!instance->getObject()->isStatic()) {
                    action = instance->getObject()->getDefaultAction();
                }
            } else {
                image = ImageManager::instance()->get(image_id);
            }
        }
        entry->forceUpdate = (action != 0);

        if (action) {
            ActionVisual* actionVisual = action->getVisual<ActionVisual>();
            bool colorOverlay = actionVisual->isColorOverlay();
            // assumed all have the same size
            if (actionVisual->isAnimationOverlay()) {
                std::map<int32_t, AnimationPtr> animations = actionVisual->getAnimationOverlay(angle);
                std::map<int32_t, AnimationPtr>::iterator it = animations.begin();
                std::vector<ImagePtr>* animOverlays = new std::vector<ImagePtr>();
                std::vector<OverlayColors*>* animationColorOverlays = colorOverlay ? new std::vector<OverlayColors*>() : 0;
                for (; it != animations.end(); ++it) {
                    uint32_t animationTime = instance->getActionRuntime() % it->second->getDuration();
                    image = it->second->getFrameByTimestamp(animationTime);
                    animOverlays->push_back(image);
                    
                    if (colorOverlay) {
                        OverlayColors* co = actionVisual->getColorOverlay(angle, it->first);
                        if (co) {
                            AnimationPtr ovAnim = co->getColorOverlayAnimation();
                            animationTime = instance->getActionRuntime() % ovAnim->getDuration();
                            co->setColorOverlayImage(ovAnim->getFrameByTimestamp(animationTime));
                        }
                        animationColorOverlays->push_back(co);
                    }
                    // works only for one animation
                    int32_t actionFrame = it->second->getActionFrame();
                    if (actionFrame != -1) {
                        int32_t newFrame = it->second->getFrameIndex(animationTime);
                        if (item->currentFrame != newFrame) {
                            if (actionFrame == newFrame) {
                                instance->callOnActionFrame(action, actionFrame);
                            // if action frame was skipped
                            } else if (newFrame > actionFrame && item->currentFrame < actionFrame) {
                                instance->callOnActionFrame(action, actionFrame);
                            }
                            item->currentFrame = newFrame;
                        }
                    }
                }
                // transfer ownership of the vectors to RenderItem
                item->setAnimationOverlay(animOverlays, animationColorOverlays);
            } else {
                AnimationPtr animation = action->getVisual<ActionVisual>()->getAnimationByAngle(angle);
                uint32_t animationTime = instance->getActionRuntime() % animation->getDuration();
                image = animation->getFrameByTimestamp(animationTime);
                // if the action have an animation with only one frame (idle animation) then
                // a forced update is not necessary.
                if (animation->getFrameCount() <= 1) {
                    entry->forceUpdate = false;
                }
                if (colorOverlay) {
                    OverlayColors* co = actionVisual->getColorOverlay(angle);
                    if (co) {
                        AnimationPtr ovAnim = co->getColorOverlayAnimation();
                        animationTime = instance->getActionRuntime() % ovAnim->getDuration();
                        co->setColorOverlayImage(ovAnim->getFrameByTimestamp(animationTime));
                        item->setColorOverlay(co);
                    }
                }
                int32_t actionFrame = animation->getActionFrame();
                if (actionFrame != -1) {
                    if (item->image != image) {
                        int32_t newFrame = animation->getFrameIndex(animationTime);
                        if (actionFrame == newFrame) {
                            instance->callOnActionFrame(action, actionFrame);
                        // if action frame was skipped
                        } else if (newFrame > actionFrame && item->currentFrame < actionFrame) {
                            instance->callOnActionFrame(action, actionFrame);
                        }
                        item->currentFrame = newFrame;
                    }
                }
            }
        }

        bool newPosition = false;
        if (image != item->image) {
            if (!item->image || !image) {
                newPosition = true;
            } else if (image->getWidth() != item->image->getWidth() ||
                        image->getHeight() != item->image->getHeight() ||
                        image->getXShift() != item->image->getXShift() ||
                        image->getYShift() != item->image->getYShift()) {
                            newPosition = true;
            }
            item->image = image;
        }
        return newPosition;
    }

    void LayerCache::updatePosition(Entry* entry) {
        RenderItem* item = m_renderItems[entry->instanceIndex];
        Instance* instance = item->instance;
        ExactModelCoordinate mapCoords = instance->getLocationRef().getMapCoordinates();
        DoublePoint3D screenPosition = m_camera->toVirtualScreenCoordinates(mapCoords);
        ImagePtr image = item->image;

        if (image) {
            int32_t w = image->getWidth();
            int32_t h = image->getHeight();
            screenPosition.x = (screenPosition.x - w / 2) + image->getXShift();
            screenPosition.y = (screenPosition.y - h / 2) + image->getYShift();
            item->bbox.w = w;
            item->bbox.h = h;
        } else {
            item->bbox.w = 0;
            item->bbox.h = 0;
        }
        item->screenpoint = screenPosition;
        item->bbox.x = static_cast<int32_t>(screenPosition.x);
        item->bbox.y = static_cast<int32_t>(screenPosition.y);

        updateScreenCoordinate(item);

        CacheTree::Node* node = m_tree->find_container(item->bbox);
        if (node) {
            if (node != entry->node) {
                if (entry->node) {
                    entry->node->data().erase(entry->entryIndex);
                }
                entry->node = node;
                node->data().insert(entry->entryIndex);
            }
        }
    }

    inline void LayerCache::updateScreenCoordinate(RenderItem* item, bool changedZoom) {
        Point3D screenPoint = m_camera->virtualScreenToScreen(item->screenpoint);
        // NOTE:
        // One would expect this to be necessary here,
        // however it works the same without, sofar
        // m_camera->calculateZValue(screenPoint);
        // item->screenpoint.z = -screenPoint.z;
        item->dimensions.x = screenPoint.x;
        item->dimensions.y = screenPoint.y;

        if (changedZoom) {
            if (m_zoomed) {
                item->dimensions.w = round(static_cast<double>(item->bbox.w) * m_zoom);
                item->dimensions.h = round(static_cast<double>(item->bbox.h) * m_zoom);
            } else {
                item->dimensions.w = item->bbox.w;
                item->dimensions.h = item->bbox.h;
            }
        }
    }

    void LayerCache::sortRenderList(RenderList& renderlist) {
        if (renderlist.empty()) {
            return;
        }
        // We want to put every z value in layer z range.
        // To do it, we simply solve
        // { y1 = a*x1 + b
        // { y2 = a*x2 + b
        // where [y1,y2]' = layer z offset min/max is required z range,
        // and [x1,x2]' is expected min,max z coords.

        // more an workaround, because z values are wrong in case of inverted top with bottom
        if (!m_needSorting && !m_layer->isStatic()) {
        //if (!m_needSorting) {
            float det = m_zMin - m_zMax;
            if (fabs(det) > FLT_EPSILON) {
                static const float globalrange = 200.0;
                static const float stackdelta = (FLT_EPSILON * 100.0);
                int32_t numlayers = m_layer->getLayerCount();
                float lmin = m_layer->getZOffset();
                float lmax = lmin + globalrange/numlayers;
                float a = (lmin - lmax) / det;
                float b = (lmax * m_zMin - lmin * m_zMax) / det;

                RenderList::iterator it = renderlist.begin();
                for ( ; it != renderlist.end(); ++it) {
                    InstanceVisual* vis = (*it)->instance->getVisual<InstanceVisual>();
                    float& z = (*it)->vertexZ;
                    z = (a * (*it)->screenpoint.z + b) + vis->getStackPosition() * stackdelta;
                }
            }
        } else {
            SortingStrategy strat = m_layer->getSortingStrategy();
            switch (strat) {
                case SORTING_CAMERA: {
                    InstanceDistanceSortCamera ids;
                    std::stable_sort(renderlist.begin(), renderlist.end(), ids);
                } break;
                case SORTING_LOCATION: {
                    InstanceDistanceSortLocation ids(m_camera->getRotation());
                    std::stable_sort(renderlist.begin(), renderlist.end(), ids);
                } break;
                case SORTING_CAMERA_AND_LOCATION: {
                    InstanceDistanceSortCameraAndLocation ids;
                    std::stable_sort(renderlist.begin(), renderlist.end(), ids);
                } break;
                default: {
                    InstanceDistanceSortCamera ids;
                    std::stable_sort(renderlist.begin(), renderlist.end(), ids);
                } break;
            }
        }
    }

    ImagePtr LayerCache::getCacheImage() {
        return m_cacheImage;
    }

    void LayerCache::setCacheImage(ImagePtr image) {
        m_cacheImage = image;
    }
}