WorldBase/Infinite/Toric: Fixed a crash when trying to find neighbors without a KD tree.

src/Engine/core/worldBase.h

@@ -81,9 +81,6 @@ private:
 	/// <summary>A list of agents (sorted by time) that will be added to the simulation in the future.</summary>
 	AgentQueue agentsToAdd;
 
-	/// <summary>A kd-tree of agent positions, used for nearest-neighbor queries.</summary>
-	AgentKDTree* agentKDTree;
-
 	/// <summary>A mapping from agent IDs to positions in the agents_ list.</summary>
 	/// <remarks>Because agents can be removed during the simulation, the ID of an agent is not necessarily the same 
 	/// as its position in the list. This is why we need this extra administration.
@@ -103,6 +100,9 @@ protected:
 	/// <summary>A list containing all agents that are currently in the crowd.</summary>
 	std::vector<Agent*> agents_;
 
+	/// <summary>A kd-tree of agent positions, used for nearest-neighbor queries.</summary>
+	AgentKDTree* agentKDTree;
+
 	/// <summary>The length (in seconds) of a simulation step.</summary>
 	float delta_time_;
 

src/Engine/core/worldInfinite.cpp

@@ -30,10 +30,14 @@ WorldInfinite::WorldInfinite() : WorldBase(INFINITE_WORLD)
 
 NeighborList WorldInfinite::ComputeNeighbors(const Vector2D& position, float search_radius, const Agent* queryingAgent) const
 {
-	const auto& agents = computeNeighboringAgents_Flat(position, search_radius, queryingAgent);
-	vector<PhantomAgent> phantoms;
-	for (const Agent* agent : agents)
-		phantoms.push_back(PhantomAgent(agent->getPosition(), agent->getVelocity(), agent));
+	vector<PhantomAgent> phantoms; 
+	if (agentKDTree != nullptr)
+	{
+		const auto& agents = computeNeighboringAgents_Flat(position, search_radius, queryingAgent);
+
+		for (const Agent* agent : agents)
+			phantoms.push_back(PhantomAgent(agent->getPosition(), agent->getVelocity(), agent));
+	}
 
 	return { phantoms, computeNeighboringObstacles_Flat(position, search_radius) };
 }

src/Engine/core/worldToric.cpp

@@ -32,10 +32,13 @@ WorldToric::WorldToric(float width, float height)
 void WorldToric::computeNeighbors_Displaced(const Vector2D& position, const Vector2D& displacement, float search_radius, const Agent* queryingAgent,
 	NeighborList& result) const
 {
-	// agents
-	const auto& agents = computeNeighboringAgents_Flat(position + displacement, search_radius, queryingAgent);
-	for (const Agent* agent : agents)
-		result.first.push_back(PhantomAgent(agent->getPosition() - displacement, agent->getVelocity(), agent));
+	if (agentKDTree != nullptr)
+	{
+		// agents
+		const auto& agents = computeNeighboringAgents_Flat(position + displacement, search_radius, queryingAgent);
+		for (const Agent* agent : agents)
+			result.first.push_back(PhantomAgent(agent->getPosition() - displacement, agent->getVelocity(), agent));
+	}
 
 	// obstacles
 	const auto& obstacles = computeNeighboringObstacles_Flat(position + displacement, search_radius);