How to trigger drawing bounding boxes for all static mesh components with a key press

Development Programming & Scripting Blueprint
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1

Hi,

I have created a blueprint called BP_ObjectDetection which draws a bounding box on a static mesh component. This blueprint allows a user to select a static mesh from the editor once as blueprint actor instance has been placed in a level.

If I define event graph with the Begin EventPlay node, and connect it to my Draw BBox function, all three object bounding boxes appear when I press the play button.

ue5-cv-od-001-main-editor-updated-level-with-multiple-actors-and-bounding-boxes
ue5-cv-od-001-main-editor-updated-level-with-multiple-actors-and-bounding-boxes1286×726 55 KB

However, if I disconnect the Begin EventPlay node and connect a Keyboard Event B to the Draw BBox function as shown below and run the game, a bounding box is displayed for only one actor.

ue5-cv-od-056-bp-od-event-graph-draw-bbox-on-keyboard-event-b
ue5-cv-od-056-bp-od-event-graph-draw-bbox-on-keyboard-event-b560×474 34.9 KB

ue5-cv-od-100-main-editor-bp-od-displaying-bounding-box-for-only-one-actor
ue5-cv-od-100-main-editor-bp-od-displaying-bounding-box-for-only-one-actor1373×874 60.3 KB

Q01: What should I do to display a bounding box for all static mesh component actors in the scene that are created using my BP_ObjectDetection blueprint ?

Thanks!

2

Hey @elvis.dowson!

Could you show us the code for your BP_ObjectDetection?

I’m thinking it has something to do with your variable reference being singular and BeginPlay running on every creation AT creation…

Have you tried “Detect,create,detect,create,detect”?

3

Hi,

I have attached screenshots of the graphs for the three functions. I’m using UE5.5.4

Function: Get Vector Permutations ()

ue5-cv-od-037-bp-od-function-get-vector-permutations-10-bp-graph
ue5-cv-od-037-bp-od-function-get-vector-permutations-10-bp-graph2072×842 330 KB

Function: Get Bounding Box ()

ue5-cv-od-047-bp-od-function-get-bounding-box-10-bp-graph
ue5-cv-od-047-bp-od-function-get-bounding-box-10-bp-graph2858×959 337 KB

Function: Draw BBox()

ue5-cv-od-051-bp-od-function-draw-bbox-04-bp-graph
ue5-cv-od-051-bp-od-function-draw-bbox-04-bp-graph1866×861 201 KB

BP_ObjectDetection Event Graph:

ue5-cv-od-052-bp-od-event-graph-setup-nodes
ue5-cv-od-052-bp-od-event-graph-setup-nodes536×292 29.4 KB

Thanks!

4

Hey, great start!

But where are Get Bounding Box and Get Vector Permuations being called?

Also, how are you setting the “Static Mesh” variable?

Also I noticed you using the () at the end like in C++,
In BP, I like to use F_GetVectorPermutations and Event_BlahblahEvent for distinguishing. :slight_smile:

5

Hi,

Only the Draw BBox function is being used right now.

The static mesh variable is assigned to SM_Chair by default.

ue5-cv-od-018-bp-od-set-static-mesh-variable-properties
ue5-cv-od-018-bp-od-set-static-mesh-variable-properties334×502 19.7 KB

Here is a screenshot of the construction script for BP_ObjectDetection

ue5-cv-od-024-bp-od-construction-script-static-mesh-component-connected-to-set-static-mesh
ue5-cv-od-024-bp-od-construction-script-static-mesh-component-connected-to-set-static-mesh1678×1191 131 KB

Once I drag a BP_ObjectDetection actor to a level using the main editor, I change the default SM_Chair to another static mesh using the main editor.

6

Okay, I’m starting to see here.

There are multiple BP_ObjectDetection’s in this scene: Two that are chairs and one that is a table, correct?

So what you need to do here is have a dispatcher, if you want to hit all of them!

Check that out, look specifically at the dispatcher section.
You’ll need the input (“B”) to be taken in somewhere OTHER than these actors (because only one actor can accept the input) then trigger an event dispatcher, and the BP_ObjectDetection’s need to have a delegate that is listening for that dispatch. Then off THAT run your lines. :slight_smile:

Hope that helps!