demands.cpp

00001 
00003 #include "../stdafx.h"
00004 #include "../station_base.h"
00005 #include "../settings_type.h"
00006 #include "../newgrf_cargo.h"
00007 #include "../cargotype.h"
00008 #include "../core/math_func.hpp"
00009 #include "demands.h"
00010 #include <list>
00011 
00012 typedef std::list<NodeID> NodeList;
00013 
00022 void SymmetricScaler::SetDemands(LinkGraphComponent *graph, NodeID from_id, NodeID to_id, uint demand_forw)
00023 {
00024   if (graph->GetNode(from_id).demand > 0) {
00025     uint demand_back = demand_forw * this->mod_size / 100;
00026     uint undelivered = graph->GetNode(to_id).undelivered_supply;
00027     if (demand_back > undelivered) {
00028       demand_back = undelivered;
00029       demand_forw = max(1U, demand_back * 100 / this->mod_size);
00030     }
00031     this->Scaler::SetDemands(graph, to_id, from_id, demand_back);
00032   }
00033 
00034   this->Scaler::SetDemands(graph, from_id, to_id, demand_forw);
00035 }
00036 
00045 FORCEINLINE void Scaler::SetDemands(LinkGraphComponent *graph, NodeID from_id, NodeID to_id, uint demand_forw)
00046 {
00047   Edge &forward = graph->GetEdge(from_id, to_id);
00048   forward.demand += demand_forw;
00049   forward.unsatisfied_demand += demand_forw;
00050   graph->GetNode(from_id).undelivered_supply -= demand_forw;
00051 }
00052 
00057 template<class Tscaler>
00058 void DemandCalculator::CalcDemand(LinkGraphComponent *graph, Tscaler scaler)
00059 {
00060   NodeList supplies;
00061   NodeList demands;
00062   uint num_supplies = 0;
00063   uint num_demands = 0;
00064 
00065   for (NodeID node = 0; node < graph->GetSize(); node++) {
00066     Node &n = graph->GetNode(node);
00067     scaler.AddNode(n);
00068     if (n.supply > 0) {
00069       supplies.push_back(node);
00070       num_supplies++;
00071     }
00072     if (n.demand > 0) {
00073       demands.push_back(node);
00074       num_demands++;
00075     }
00076   }
00077 
00078   if (num_supplies == 0 || num_demands == 0) return;
00079 
00080   /* mean acceptance attributed to each node. If the distribution is
00081    * symmetric this is relative to remote supply, otherwise it is
00082    * relative to remote demand.
00083    */
00084   scaler.SetDemandPerNode(num_demands);
00085   uint chance = 0;
00086 
00087   while (!supplies.empty() && !demands.empty()) {
00088     NodeID node1 = supplies.front();
00089     supplies.pop_front();
00090 
00091     Node &from = graph->GetNode(node1);
00092 
00093     for (uint i = 0; i < num_demands; ++i) {
00094       assert(!demands.empty());
00095       NodeID node2 = demands.front();
00096       demands.pop_front();
00097       if (node1 == node2) {
00098         if (demands.empty() && supplies.empty()) {
00099           /* only one node with supply and demand left */
00100           return;
00101         } else {
00102           demands.push_back(node2);
00103           continue;
00104         }
00105       }
00106       Node &to = graph->GetNode(node2);
00107 
00108       int32 supply = scaler.EffectiveSupply(from, to);
00109       assert(supply > 0);
00110 
00111       /* scale the distance by mod_dist around max_distance */
00112       int32 distance = this->max_distance - (this->max_distance -
00113           (int32)graph->GetEdge(node1, node2).distance) * this->mod_dist / 100;
00114 
00115       /* scale the accuracy by distance around accuracy / 2 */
00116       int32 divisor = this->accuracy * (this->mod_dist - 50) / 100 +
00117           this->accuracy * distance / this->max_distance + 1;
00118 
00119       assert(divisor > 0);
00120 
00121       uint demand_forw = 0;
00122       if (divisor <= supply) {
00123         /* at first only distribute demand if
00124          * effective supply / accuracy divisor >= 1
00125          * Others are too small or too far away to be considered.
00126          */
00127         demand_forw = supply / divisor;
00128       } else if (++chance > this->accuracy * num_demands * num_supplies) {
00129         /* After some trying, if there is still supply left, distribute
00130          * demand also to other nodes.
00131          */
00132         demand_forw = 1;
00133       }
00134 
00135       demand_forw = min(demand_forw, from.undelivered_supply);
00136 
00137       scaler.SetDemands(graph, node1, node2, demand_forw);
00138 
00139       if (scaler.DemandLeft(to)) {
00140         demands.push_back(node2);
00141       } else {
00142         num_demands--;
00143       }
00144 
00145       if (from.undelivered_supply == 0) break;
00146 
00147     }
00148     if (from.undelivered_supply != 0) {
00149       supplies.push_back(node1);
00150     } else {
00151       num_supplies--;
00152     }
00153   }
00154 }
00155 
00160 DemandCalculator::DemandCalculator(LinkGraphComponent *graph) :
00161   max_distance(MapSizeX() + MapSizeY() + 1)
00162 {
00163   CargoID cargo = graph->GetCargo();
00164   const LinkGraphSettings &settings = graph->GetSettings();
00165 
00166   this->accuracy = settings.accuracy;
00167   this->mod_dist = settings.demand_distance;
00168   if (this->mod_dist > 100) {
00169     /* increase effect of mod_dist > 100 */
00170     int over100 = this->mod_dist - 100;
00171     this->mod_dist = 100 + over100 * over100;
00172   }
00173 
00174   switch (settings.GetDistributionType(cargo)) {
00175     case DT_SYMMETRIC:
00176       this->CalcDemand<SymmetricScaler>(graph, SymmetricScaler(settings.demand_size));
00177       break;
00178     case DT_ASYMMETRIC:
00179       this->CalcDemand<AsymmetricScaler>(graph, AsymmetricScaler());
00180       break;
00181     default:
00182       NOT_REACHED();
00183   }
00184 }

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