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Placeable Markers

In this section, we'll spawn items like NPCs, power ups etc in our dungeon.

For this, we'll do the following:

  • Use the Spawn Item node in the flow graph. This will add items in the layout graph
  • Create Placeable Marker assets in the content browser and drop a few of them in the snap modules so that the builder can spawn them at those places when necessary
  • Use the Theme engine to spawn the markers

Spawn Items in Flow Graph

Open up the flow graph and assign the module database in the editor settings like before

Create a new Spawn Items node and link it up as shown below:

Inspect the properties of the Spawn Items node. Add two paths in the Paths array and assign the ids of the main path (main) and the alternate path (alt)

We'd like to eventually spawn something in the modules using the theme file. We'll provide a marker name here, so we can create a corresponding marker node in the theme file and add our NPC blueprint there

Set the Marker Name parameter to Grunt

Leave the rest of the properties unchanged and hit Build

The nodes now in the green path (main) and orange path (alt) have red enemy items that were created using the Spawn Item node

Add a description to this node

Placeable Markers

A placeable marker is an asset you create in the content browser. You can then drag and drop these assets anywhere on the scene. You can then use the theme file to spawn objects at that location.

A placeable marker asset can contain more than one marker name. For example, a placeable marker asset named PM_Enemies may contain a list of marker names like (Grunt, FireTroll, IceTroll, Goblin). In your snap module, you'd place these markers in appropriate locations (say 10 different locations within the room).

If the dungeon builder needs to spawn a Grunt marker 4 times inside the room, it will first find all the existing and compatible marker assets placed in the room. In this case PM_Enemies would be compatible since it contains a Grunt marker. Since we have 10 of these in the room module, it will randomly pick 4 from them and use the theme file to spawn the grunt blueprint

Create Asset

Right click on the Content Browser and choose Dungeon Architect > Placeable Marker

Rename the asset to PM_Enemies

Double click the asset to open up the editor. Add a Grunt marker (since we specified this earlier in the Spawn Items node). Add a few more markers for future use like IceTroll, FireTroll, Goblin

Save the asset and close this editor

Add to Snap Modules

Open up the previously created room module

We've added a bit of geometry to the room. The snap system gives complete freedom to the artist to design the room as they see fit. In that same spirit, the artist should also have control on where the markers spawn. This is where placeable markers come in

Drag drop the placeable marker asset that you've created before, on to the scene

When you drag drop a marker asset in the scene, it will create a placeable marker actor. Select the actor that you just dropped

It will show some debug info, like the maker asset name, and the marker names it contains

Rotate the actor as needed. The red arrow shows the orientation of the marker. When the theme engine spawns an actor here, it will do so with this rotation

Add a few more markers. Add at least 4 markers, since we are adding a maximum of 4 enemy items per node in the flow graph using Spawn Item, but adding more is always better. We'll add a few on top of the bridge, on the ramp, and some more on the ground

Do this for all the modules you've created so far that would need this marker in it

Open up the Lift module and add a few more placeable markers there

Rebuild Module Database Cache

If you add / remove a placeable marker from a snap module, you'll need to rebuild the module database cache

Open up the Module database we've created in the previous section and click Build Module Cache button. Save and close the module database editor


This is an important step. Remember to rebuild the cache when needed

Update Theme File

We'll use a theme file to actually spawn our enemy blueprint.

Open Theme Editor

Open up the existing theme file we created in the previous section.

Change Builder Type

Click somewhere on an empty space in the graph to show the theme properties in the Details tab.

Scroll down to the Advanced section and set the Builder Class to SnapGridFlowBuilder

This will update all the marker nodes for that builder.


This will remove unused marker nodes and add the necessary marker nodes used by this builder. Since the Snap Grid Flow builder doesn't have any built-in marker nodes, it will not create any new nodes

Create Marker

In the previous section, we assign the marker name of Grunt in the Spawn Items node. In the theme file, we'll create a new marker node and name it Grunt

Right click on the graph and choose Add Marker Node

Select the marker node and change the Marker name to Grunt in the properties

Add Enemy actor

Add your NPC character blueprint here. For this tutorial, we'll add a cube and adjust the size and scale

Resize the theme editor a bit and drag drop the proto cube on to the theme editor

This will create a new mesh node. Add it to the Grunt marker node

Select the cube mesh node and set the scale to (1, 1, 2)

Add a Material Override entry

Assign a red material to it

Save and close the Theme Editor

Build Dungeon

Open the map where we previously configured our dungeon and build it.

You'll see that enemies start to spawn at the locations where you've placed the markers

You can use this system to spawn anything (treasure chests, weapon racks, power ups or any gameplay blueprint)