In this section we create a new behaviour module. This module is a simple follow target module.
Writing the behaviour module
First thing to do is create a class and hinerit from the base BehaviourModule class. With a constructor a desctructor and a static creator function used by atoms to create an isntance of this module.
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();
}
Lets add some attributes to our node. In this case we need only a target position. The attributes of the modules are stored inside a MapMetadata object, and you can add new attribute using the addAttribute function. So lets add this attribute inside the constructor.
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, so we need to override the initFrame function.
You can override other function linke the endFrame or initSimulation or agentsCreated but in this case we need only the initFrame
void initFrame(const std::vector<Atoms::Agent*>& agents, Atoms::AgentGroup* agentGroup = nullptr)
{
}
In the init frame we need to get our targetPosition value and iterate over each agent to get the position and set the new direction
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());
}
}
We created the target position attribute as overraidable per agent but we didn't put the code to handle it. So let's add now. When you override an attribute, Atoms creates an entry using the agent group id inside the mapmetadata saved as AttributeName_override.
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 imporve the performance of the module you can add tbb to parallelize the main for loop
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());
}
}
});
}
Register the behaviour module
The main module is now ready so we need to register it to the behaviour module factory
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 opendexr 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 the folder where the plugin is located to the ATOMS_PLUGINS_PATH environment variable. Then the module is automatically loaded when you load atoms
Final code
#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());
}
}
});
}
static Atoms::BehaviourModule* creator(const std::string& parameter);
};
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;
}
}