Writing an Atoms graph node (AtomsUnreal)

You can create custom dependency graph nodes, which carry out custom operations based on their incoming data. Each node type you write can be added to the agent dependency graph.

This is an example of a node that returns the intersection between a ray and an height field.

#include <AtomsGraph/Globals.h>
#include <Atoms/Globals.h>
#include <AtomsGraph/Ports.h>
#include <AtomsGraph/NodeFactory.h>
#include <Atoms/HeightFields.h>
#include <Atoms/HeightField.h>

class HeighFieldIntersectorNode :
	public AtomsGraph::Node
{
public:

	NODE_STANDARD_MEMBERS

	HeighFieldIntersectorNode();

	virtual ~HeighFieldIntersectorNode();

	virtual bool compute();

private:

	AtomsGraph::StringPort *m_heightFieldNamePort;

	AtomsGraph::VectorPort *m_rayOriginPort;

	AtomsGraph::VectorPort *m_rayDirectionPort;

	AtomsGraph::VectorPort *m_outPositionPort;

	AtomsGraph::VectorPort *m_outNormalPort;
};

#include "HeighFieldIntersectorNode.h"
#include <Atoms/MeshHeightField.h>

#define HEIGHTFIELDINTERSECTOR_NODE_ID 999999 // this must be unique

NODE_STANDARD_MEMBERS_IMPL(HeighFieldIntersectorNode)
unsigned int HeighFieldIntersectorNode::staticTypeId() { return HEIGHTFIELDINTERSECTOR_NODE_ID; }
std::string HeighFieldIntersectorNode::staticTypeStr() { return std::string("HeighFieldIntersectorNode"); }

HeighFieldIntersectorNode::HeighFieldIntersectorNode()
{
	m_heightFieldNamePort = new AtomsGraph::StringPort("heightField");
	m_rayOriginPort = new AtomsGraph::VectorPort("rayOrigin");
	m_rayDirectionPort = new AtomsGraph::VectorPort("rayDirection");
	m_outPositionPort = new AtomsGraph::VectorPort("outPosition");
	m_outNormalPort = new AtomsGraph::VectorPort("outNormal");

	// add input and output ports
	addInputPort(m_heightFieldNamePort);
	addInputPort(m_rayOriginPort);
	addInputPort(m_rayDirectionPort);
	addOutputPort(m_outPositionPort);
	addOutputPort(m_outNormalPort);
}

HeighFieldIntersectorNode::~HeighFieldIntersectorNode()
{
	// the parent destructor automatically deletes all the ports so we don't need to delete them here
}

bool HeighFieldIntersectorNode::compute()
{
	Atoms::HeightFields& fields = Atoms::HeightFields::instance();

	// get the height field name from the input port
	const std::string& heightFieldName = m_heightFieldNamePort->getRef();

	// check if the height field exist
	auto heightField = fields.heightField(heightFieldName);

	Atoms::MeshHeightField* meshHf = nullptr;
	if (heightField && heightField->typeId() == Atoms::MeshHeightField::staticTypeId())
	{
		meshHf = static_cast<Atoms::MeshHeightField*>(heightField.get());
	}

	if (!meshHf)
		return false;


	// compute the intersection
	Atoms::HeightField::HitResult hitResult;
	if (meshHf->intersect(m_rayOriginPort->getRef(), m_rayDirectionPort->getRef(), hitResult, false))
	{
		
		AtomsCore::Vector3 projectedPos = m_rayOriginPort->getRef() + double(hitResult.t) * m_rayDirectionPort->getRef();

		// compute the normal from the barycentric coords of the intersection
		std::vector<AtomsCore::Vector3f> &normals = meshHf->mesh().normals();
		AtomsCore::Vector3 hfNormal = hitResult.uv.x * normals[hitResult.faceId * 3] + hitResult.uv.y * normals[hitResult.faceId * 3 + 1] + (1.0f - hitResult.uv.x - hitResult.uv.y) * normals[hitResult.faceId * 3 + 2];
		hfNormal.normalize();

		// set the output ports
		m_outPositionPort->set(projectedPos);
		m_outNormalPort->set(hfNormal);
	}

	return true;
}

Register the new node to the factory

#include "HeighFieldIntersectorNode.h"

void FAtomsUnrealTestGameModule::StartupModule()
{
	AtomsGraph::NodeFactory& manager = AtomsGraph::NodeFactory::instance();
	manager.registerNode(HeighFieldIntersectorNode::staticTypeStr(), &HeighFieldIntersectorNode::creator);
}

void FAtomsUnrealTestGameModule::ShutdownModule()
{
	AtomsGraph::NodeFactory& manager = AtomsGraph::NodeFactory::instance();
	manager.deregisterNode(HeighFieldIntersectorNode::staticTypeStr());
}