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In this section we are going to create a new behaviour module. This behaviour module is a simple follow target module.

Writing the behaviour module

Create a new class and inherit from the base Atoms::BehaviourModule class. Define a a constructor, a destructor and a static creator function (needed by Atoms to create an instance of this module).

Code Block

language	cpp

class FollowTargetModule: public Atoms::BehaviourModule
{
	public:

		FollowTargetModule()
		{}

		virtual ~FollowTargetModule()
		{}

		static Atoms::BehaviourModule* creator(const std::string& parameter);
};

Atoms::BehaviourModule* FollowTargetModule::creator(const std::string& parameter)
{
	return new FollowTargetModule();
}

For this module we'll need only a target position attribute. The attributes of the module are stored inside a MapMetadata object, you can add new attributes using the addAttribute function. Attributes should always be added inside the constructor.

The third attribute of the addAttribute method defines if the attribute is overridable per agent or not. In this example we'll make it overridable.

Code Block

language	cpp

FollowTargetModule(): Atoms::BehaviourModule()
{
	AtomsCore::Vector3Metadata targetPosition(AtomsCore::Vector3(0.0,0.0,0.0));
	// The last argumet specify if this attribute can be override per agent
	addAttribute("targetPosition", &targerPosition, true);
}

Now we need to compute the new agent direction at each frame before the agent pose is computed. This will be done inside the initFrame method.

For this example we won't need to override any other method.

Code Block

language	cpp

void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
{
}

In the initFrame function get the targetPosition value, iterate over each agent to read the position and set their new direction.

Code Block

language	cpp

void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
{
	// Get the target position from the moduel attribute
	AtomsCore::MapMetadata& attributeMap = attributes();
	AtomsCore::Vector3& targetPosition = attributeMap.getTypedEntry<AtomsCore::Vector3Metadata>("targetPosition")->get();

	// iterate over each agent
	for(Atoms::Agent* agent: agents)
	{
		if (!agent)
			continue;
		//get the agent position
		AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position");
		AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction");
		if(!positionPtr || !directionPtr )
			continue;

		// compute the new direction
		directionPtr->set((targetPosition - positionPtr->get()).normalized()); 
	}
}

The target position attribute is overridable per agent, but the code to handle it isn't there yet. When you override an attribute, a new map metadata named "AttributeName_override" is created. The keys of this map metadata are the agent group ids, but they will be present only when the user specifies an override from inside his 3D application.

In order to know if an agent has an override, please check the metadata map. If it's not there, please use the global attribute.

Code Block

language	cpp

void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
{
	// Get the target position from the moduel attribute
	AtomsCore::MapMetadata& attributeMap = attributes();
	AtomsCore::Vector3& targetPosition = attributeMap.getTypedEntry<AtomsCore::Vector3Metadata>("targetPosition")->get();

	//get the override map metadata
	AtomsPtr<AtomsCore::MapMetadata> targetPositionOverride = attributeMap.getTypedEntry<AtomsCore::MapMetadata>("targetPosition_override");

	// used to store the groupId as string
	char groupIdChar[12];
	std::string groupIdStr;
	groupIdStr.reserve(12);

	// iterate over each agent
	for(Atoms::Agent* agent: agents)
	{
		if (!agent)
			continue;
		//get the agent position
		AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position");
		AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction");
		if(!positionPtr || !directionPtr )
			continue;

		// get the agent group id
		AtomsPtr<AtomsCore::IntMetadata> groupIdPtr = agent->metadata().getTypedEntry<AtomsCore::IntMetadata>("groupId");
		if (!groupIdPtr)
			continue;

		//convert the groupId to a string since the map metadata use only strings as key
		sprintf(groupIdChar, "%d", groupIdPtr->value());
		groupIdStr = groupIdChar;

		//check if the agent is inside the override map
		AtomsPtr<AtomsCore::Vector3Metadata> overrideTargetPos = targetPositionOverride->getTypedEntry<AtomsCore::Vector3Metadata>(groupIdStr);
		if (overrideTargetPos)
		{
			// compute the new direction
			directionPtr->set((overrideTargetPos->get() - positionPtr->get()).normalized()); 
		}
		else
		{
			// compute the new direction
			directionPtr->set((targetPosition - positionPtr->get()).normalized()); 
		}
	}
}

If you want improve the performance of the module you can add tbb to parallelize the main for loop.

Code Block

language	cpp

void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
{
	// Get the target position from the moduel attribute
	AtomsCore::MapMetadata& attributeMap = attributes();
	AtomsCore::Vector3& targetPosition = attributeMap.getTypedEntry<AtomsCore::Vector3Metadata>("targetPosition")->get();

	//get the override map metadata
	AtomsPtr<AtomsCore::MapMetadata> targetPositionOverride = attributeMap.getTypedEntry<AtomsCore::MapMetadata>("targetPosition_override");



	// iterate over each agent
	tbb::parallel_for(tbb::blocked_range<unsigned int>(0, agents.size()),
		[&](const tbb::blocked_range<size_t>& r)
	{
		// used to store the groupId as string
		char groupIdChar[12];
		std::string groupIdStr;
		groupIdStr.reserve(12);

		for (size_t i = r.begin(); i < r.end(); i++)
		{
			Atoms::Agent* agent = agents[i];

			if (!agent)
				continue;
			//get the agent position
			AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position");
			AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction");
			if(!positionPtr || !directionPtr )
				continue;

			// get the agent group id
			AtomsPtr<AtomsCore::IntMetadata> groupIdPtr = agent->metadata().getTypedEntry<AtomsCore::IntMetadata>("groupId");
			if (!groupIdPtr)
				continue;
	
			//convert the groupId to a string since the map metadata use only strings as key
			sprintf(groupIdChar, "%d", groupIdPtr->value());
			groupIdStr = groupIdChar;
	
			//check if the agent is inside the override map
			AtomsPtr<AtomsCore::Vector3Metadata> overrideTargetPos = targetPositionOverride->getTypedEntry<AtomsCore::Vector3Metadata>(groupIdStr);
			if (overrideTargetPos)
			{
				// compute the new direction
				directionPtr->set((overrideTargetPos->get() - positionPtr->get()).normalized()); 
			}
			else
			{
				// compute the new direction
				directionPtr->set((targetPosition - positionPtr->get()).normalized()); 
			}
		}
	});
}

Add visual debugging options

Lets implement a the draw function to visually debug the direction vector. Add a std::vector<AtomsCore::Vector3> m_drawLines to the class to store the lines data.

Inside the preDraw function you can collect the data form the agentse because it is called only if the time changes.

Then inside the draw function you can finally call the draw lines function to draw some lines.

Code Block

language	cpp

void preDraw(Atoms::DrawContext* context, const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup)
{
	// The pre draw function is called only when theon time is changed or some attribute is changedchange,
	// so 	// we canit's safe to collect the data from the agents here
	m_drawLines.resize(agents.size()*2);
	for (size_t i = 0; i < agents.size(); i++) 
	{
		Atoms::Agent* agent = agents[i];
		 
		//get the agent position 
		AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position"); 
		AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction"); 
		if(!positionPtr || !directionPtr ) continue;
		
		m_drawLines[i*2] = positionPtr->get();
		m_drawLines[i*2 + 1] = positionPtr->get() + directionPtr0>get();
	}
}

void draw(Atoms::DrawContext* context, const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup) 
{
	// the draw function is called when the dcc update the viewports
	context->lines(m_drawLines);
}

Register the behaviour module

Now the behaviour module must be added to the behaviour module factory.

Code Block

language	cpp

extern "C"
{
	ATOMSPLUGIN_EXPORT bool initializePlugin()
	{
		Atoms::BehaviourModules& moduleManager = Atoms::BehaviourModules::instance();
moduleManager.registerBehaviourModule("SimpleFollowTarget", &FollowTargetModule::creator, Atoms::BehaviourModules::kNative);
		return true;
	}

	ATOMSPLUGIN_EXPORT bool unitializePlugin()
	{
		Atoms::BehaviourModules& moduleManager = Atoms::BehaviourModules::instance();
		moduleManager.deregisterBehaviourModule("SimpleFollowTarget");
		return true;
	}
}

Compile the behaviour module

Windows:

In visual studio create a dll projects, add the atoms, tbb and openexr includes and add BUILD_ATOMSPLUGIN to the preprocessor definitions.

Linux:

Compile as a shared object adding the atoms, tbb and opendexr includes and BUILD_ATOMSPLUGIN to the preprocessor definitions.

Use the behaviour module

Add to the ATOMS_PLUGINS_PATH environment variable, the folder where the plugin is located. Then the module is automatically loaded when you load atoms.

Final code

Code Block

language	cpp

#pragma once
#include <Atoms/BehaviourModule.h>
#include <Atoms/Agent.h>
#include <Atoms/AgentGroup.h>
#include <AtomsUtils/Logger.h>
#include <Atoms/GlobalNames.h>
#include <AtomsCore/Metadata/IntMetadata.h>
#include <AtomsCore/Metadata/Vector3Metadata.h>
#include <tbb/parallel_for.h>
#include <algorithm>

class FollowTargetModule : public Atoms::BehaviourModule
{
public:

	FollowTargetModule(): Atoms::BehaviourModule()
	{
		AtomsCore::Vector3Metadata targetPosition(AtomsCore::Vector3(0.0,0.0,0.0));
		// The last argumet specify if this attribute can be override per agent
		addAttribute("targetPosition", &targerPosition, true);
	}

	~FollowTargetModule()
	{
	}

	void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
	{
		// Get the target position from the moduel attribute
		AtomsCore::MapMetadata& attributeMap = attributes();
		AtomsCore::Vector3& targetPosition = attributeMap.getTypedEntry<AtomsCore::Vector3Metadata>("targetPosition")->get();

		//get the override map metadata
		AtomsPtr<AtomsCore::MapMetadata> targetPositionOverride = attributeMap.getTypedEntry<AtomsCore::MapMetadata>("targetPosition_override");



		// iterate over each agent
		tbb::parallel_for(tbb::blocked_range<unsigned int>(0, agents.size()),
			[&](const tbb::blocked_range<size_t>& r)
		{
			// used to store the groupId as string
			char groupIdChar[12];
			std::string groupIdStr;
			groupIdStr.reserve(12);

			for (size_t i = r.begin(); i < r.end(); i++)
			{
				Atoms::Agent* agent = agents[i];

				if (!agent)
					continue;
				//get the agent position
				AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position");
				AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction");
				if(!positionPtr || !directionPtr )
					continue;

				// get the agent group id
				AtomsPtr<AtomsCore::IntMetadata> groupIdPtr = agent->metadata().getTypedEntry<AtomsCore::IntMetadata>("groupId");
				if (!groupIdPtr)
					continue;
		
				//convert the groupId to a string since the map metadata use only strings as key
				sprintf(groupIdChar, "%d", groupIdPtr->value());
				groupIdStr = groupIdChar;
		
				//check if the agent is inside the override map
				AtomsPtr<AtomsCore::Vector3Metadata> overrideTargetPos = targetPositionOverride->getTypedEntry<AtomsCore::Vector3Metadata>(groupIdStr);
				if (overrideTargetPos)
				{
					// compute the new direction
					directionPtr->set((overrideTargetPos->get() - positionPtr->get()).normalized()); 
				}
				else
				{
					// compute the new direction
					directionPtr->set((targetPosition - positionPtr->get()).normalized()); 
				}
			}
		});
	}

	void preDraw(Atoms::DrawContext* context, const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup)
	{
		 // The pre draw function is called only when the time is changed or some attribute is changed so
		// we can collect the data from the agents here
		m_drawLines.resize(agents.size()*2);
		for (size_t i = 0; i < agents.size(); i++) 
		{
			Atoms::Agent* agent = agents[i];

			//get the agent position 
			AtomsPtr<AtomsCore::Vector3Metadata> positionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("position"); 
			AtomsPtr<AtomsCore::Vector3Metadata> directionPtr = agent->metadata().getTypedEntry<AtomsCore::Vector3Metadata>("direction"); 
			if(!positionPtr || !directionPtr ) continue;

			m_drawLines[i*2] = positionPtr->get();
			m_drawLines[i*2 + 1] = positionPtr->get() + directionPtr0>get();
		}
	}

	void draw(Atoms::DrawContext* context, const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup) 
	{
		// the draw function is called when the dcc update the viewports
		context->lines(m_drawLines);
	}

	static Atoms::BehaviourModule* creator(const std::string& parameter);

private:

	std::vector<AtomsCore::Vector3> m_drawLines;
};

Atoms::BehaviourModule* FollowTargetModule::creator(const std::string& parameter)
{
	return new FollowTargetModule();
}

extern "C"
{
	ATOMSPLUGIN_EXPORT bool initializePlugin()
	{
		Atoms::BehaviourModules& moduleManager = Atoms::BehaviourModules::instance();
moduleManager.registerBehaviourModule("SimpleFollowTarget", &FollowTargetModule::creator, Atoms::BehaviourModules::kNative);
		return true;
	}

	ATOMSPLUGIN_EXPORT bool unitializePlugin()
	{
		Atoms::BehaviourModules& moduleManager = Atoms::BehaviourModules::instance();
		moduleManager.deregisterBehaviourModule("SimpleFollowTarget");
		return true;
	}
}

Versions Compared

Old Version 11

New Version 12

Key

Writing the behaviour module

Add visual debugging options

Register the behaviour module

Compile the behaviour module

Use the behaviour module