generate-constraints.cpp

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#include <algorithm>
#include <set>
#include <cassert>
#include <cstdlib>
#include <memory>
#include <vector>
#include <vpsc/generate-constraints.h>
#include <vpsc/constraint.h>
 
using std::set;
using std::vector;
 
std::ostream& operator <<(std::ostream &os, const Rectangle &r) {
        os << "{"<<r.minX<<","<<r.maxX<<","<<r.minY<<","<<r.maxY<<"},";
        return os;
}
Rectangle::Rectangle(double x, double X, double y, double Y) 
: minX(x),maxX(X),minY(y),maxY(Y) {
                assert(x<=X);
                assert(y<=Y);
}
 
namespace {
struct Node;
struct CmpNodePos { bool operator()(const Node* u, const Node* v) const; };
 
typedef set<Node*,CmpNodePos> NodeSet;
 
struct Node {
        Variable *v;
        const Rectangle &r;
        double pos;
        Node *firstAbove, *firstBelow;
        NodeSet leftNeighbours, rightNeighbours;
        Node(Variable *v, const Rectangle &r, double p) : v(v),r(r),pos(p) {
                firstAbove=firstBelow=nullptr;
                assert(r.width()<1e40);
        }
        void addLeftNeighbour(Node *u) {
                leftNeighbours.insert(u);
        }
        void addRightNeighbour(Node *u) {
                rightNeighbours.insert(u);
        }
        void setNeighbours(const NodeSet &left, const NodeSet &right) {
                leftNeighbours=left;
                rightNeighbours=right;
                for(Node *n : left) {
                        n->addRightNeighbour(this);
                }
                for(Node *n : right) {
                        n->addLeftNeighbour(this);
                }
        }
};
bool CmpNodePos::operator() (const Node* u, const Node* v) const {
        if (u->pos < v->pos) {
                return true;
        }
        if (v->pos < u->pos) {
                return false;
        }
        return u < v;
}
}
 
static NodeSet getLeftNeighbours(NodeSet &scanline,Node *v) {
        NodeSet leftv;
        NodeSet::iterator i=scanline.find(v);
        while(i!=scanline.begin()) {
                Node *u=*(--i);
                if(u->r.overlapX(v->r)<=0) {
                        leftv.insert(u);
                        return leftv;
                }
                if(u->r.overlapX(v->r)<=u->r.overlapY(v->r)) {
                        leftv.insert(u);
                }
        }
        return leftv;
}
static NodeSet getRightNeighbours(NodeSet &scanline,Node *v) {
        NodeSet rightv;
        NodeSet::iterator i=scanline.find(v);
        for(i++;i!=scanline.end(); i++) {
                Node *u=*(i);
                if(u->r.overlapX(v->r)<=0) {
                        rightv.insert(u);
                        return rightv;
                }
                if(u->r.overlapX(v->r)<=u->r.overlapY(v->r)) {
                        rightv.insert(u);
                }
        }
        return rightv;
}
 
typedef enum {Open, Close} EventType;
struct Event {
        EventType type;
        std::shared_ptr<Node> v;
        double pos;
        Event(EventType t, const std::shared_ptr<Node> &v, double p)
          : type(t),v(v),pos(p) {};
};
 
static bool compare_events(const Event &ea, const Event &eb) {
        if(&ea.v->r==&eb.v->r) {
                // when comparing opening and closing from the same rect
                // open must come first
                if(ea.type == Open && eb.type != Open) return true;
                return false;
        } else if(ea.pos > eb.pos) {
                return false;
        } else if(ea.pos < eb.pos) {
                return true;
        }
        return false;
}
 
int generateXConstraints(const vector<Rectangle> &rs, Variable** vars,
          Constraint** &cs, const bool useNeighbourLists) {
 
        vector<Event> events;
        events.reserve(2 * rs.size());
        for(size_t i=0;i<rs.size();i++) {
                vars[i]->desiredPosition=rs[i].getCentreX();
                auto v = std::make_shared<Node>(vars[i],rs[i],rs[i].getCentreX());
                events.emplace_back(Open,v,rs[i].getMinY());
                events.emplace_back(Close,v,rs[i].getMaxY());
        }
        std::sort(events.begin(), events.end(), compare_events);
 
        NodeSet scanline;
        vector<Constraint*> constraints;
        for(Event &e : events) {
                Node *v = e.v.get();
                if(e.type==Open) {
                        scanline.insert(v);
                        if(useNeighbourLists) {
                                v->setNeighbours(
                                        getLeftNeighbours(scanline,v),
                                        getRightNeighbours(scanline,v)
                                );
                        } else {
                                NodeSet::iterator it=scanline.find(v);
                                if(it!=scanline.begin()) {
                                        Node *u=*--it;
                                        v->firstAbove=u;
                                        u->firstBelow=v;
                                }
                                it=scanline.find(v);
                                if(++it!=scanline.end()) {
                                        Node *u=*it;
                                        v->firstBelow=u;
                                        u->firstAbove=v;
                                }
                        }
                } else {
                        // Close event
                        if(useNeighbourLists) {
                                for(Node *u : v->leftNeighbours) {
                                        double sep = (v->r.width()+u->r.width())/2.0;
                                        constraints.push_back(new Constraint(u->v,v->v,sep));
                                        u->rightNeighbours.erase(v);
                                }
                                
                                for(Node *u : v->rightNeighbours) {
                                        double sep = (v->r.width()+u->r.width())/2.0;
                                        constraints.push_back(new Constraint(v->v,u->v,sep));
                                        u->leftNeighbours.erase(v);
                                }
                        } else {
                                Node *l=v->firstAbove, *r=v->firstBelow;
                                if(l!=nullptr) {
                                        double sep = (v->r.width()+l->r.width())/2.0;
                                        constraints.push_back(new Constraint(l->v,v->v,sep));
                                        l->firstBelow=v->firstBelow;
                                }
                                if(r!=nullptr) {
                                        double sep = (v->r.width()+r->r.width())/2.0;
                                        constraints.push_back(new Constraint(v->v,r->v,sep));
                                        r->firstAbove=v->firstAbove;
                                }
                        }
                        scanline.erase(v);
                }
        }
        int m =constraints.size();
        cs=new Constraint*[m];
        for(int i=0;i<m;i++) cs[i]=constraints[i];
        return m;
}
 
int generateYConstraints(const vector<Rectangle> &rs, Variable** vars,
          Constraint** &cs) {
 
        vector<Event> events;
        events.reserve(2 * rs.size());
        for(size_t i=0;i<rs.size();i++) {
                vars[i]->desiredPosition=rs[i].getCentreY();
                auto v = std::make_shared<Node>(vars[i],rs[i],rs[i].getCentreY());
                events.emplace_back(Open,v,rs[i].getMinX());
                events.emplace_back(Close,v,rs[i].getMaxX());
        }
        std::sort(events.begin(), events.end(), compare_events);
        NodeSet scanline;
        vector<Constraint*> constraints;
        for(Event &e : events) {
                Node *v = e.v.get();
                if(e.type==Open) {
                        scanline.insert(v);
                        NodeSet::iterator i=scanline.find(v);
                        if(i!=scanline.begin()) {
                                Node *u=*--i;
                                v->firstAbove=u;
                                u->firstBelow=v;
                        }
                        i=scanline.find(v);
                        if(++i!=scanline.end())  {
                                Node *u=*i;
                                v->firstBelow=u;
                                u->firstAbove=v;
                        }
                } else {
                        // Close event
                        Node *l=v->firstAbove, *r=v->firstBelow;
                        if(l!=nullptr) {
                                double sep = (v->r.height()+l->r.height())/2.0;
                                constraints.push_back(new Constraint(l->v,v->v,sep));
                                l->firstBelow=v->firstBelow;
                        }
                        if(r!=nullptr) {
                                double sep = (v->r.height()+r->r.height())/2.0;
                                constraints.push_back(new Constraint(v->v,r->v,sep));
                                r->firstAbove=v->firstAbove;
                        }
                        scanline.erase(v);
                }
        }
        int m =constraints.size();
        cs=new Constraint*[m];
        for(int i=0;i<m;i++) cs[i]=constraints[i];
        return m;
}