logicnodes

Logic Nodes

Creating custom nodes

Create a library

We will make a new library to store the sources of custom logic nodes and keep them portable with no modifications to engine sources.

Locate your blend file and create a new Libraries folder alongside it. Navigate to the Libraries folder and create a new mynodes folder in it to place your new node.

Python

Next, we will create the logic node definition for Blender.

To do so, we have to create a file named blender.py in Libraries/mynodes folder. Armory automatically picks this file up once the library is loaded.

Define a simple node with single in/out socket like the one in the example below.

from bpy.types import Node
from arm.logicnode.arm_nodes import *
import arm.nodes_logic

class TestNode(Node, ArmLogicTreeNode):
    '''Test node'''
    bl_idname = 'LNTestNode'
    bl_label = 'Test'
    bl_icon = 'QUESTION'

    def init(self, context):
        self.inputs.new('ArmNodeSocketAction', 'In')
        self.outputs.new('ArmNodeSocketAction', 'Out')

# Add custom nodes
add_node(TestNode, category='Action')

Restarting Blender and loading the project again, the new logic node is available for placement.

Haxe

Before the project can be run, we need to implement the actual node logic in Haxe.

Start by creating the folder structure Sources/armory/logicnode/ in the same folder of blender.py.

Next, create a TestNode.hx file inside the logicnode folder just created, and place the code from below in the file.

When the node gets executed, we let it print a 'Hello, World!' string.

package armory.logicnode;

class TestNode extends LogicNode {

    public function new(tree:LogicTree) {
        super(tree);
    }

    override function run(from:Int) {
        // Logic for this node
        trace("Hello, World!");

        // Execute next action linked to this node
        runOutput(0);
    }
}

Where to next

• Example project: https://github.com/armory3d/armory_examples/tree/master/dev_logicnode

When implementing new logic nodes, browse the sources of existing nodes as a reference:

• Python definitions of Armory nodes: https://github.com/armory3d/armory/tree/master/blender/arm/logicnode

• Haxe implementation: https://github.com/armory3d/armory/tree/master/Sources/armory/logicnode