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Add a box size

Boxes are not scaled, they are modelled. Each size is a real mesh with real cardboard thickness, its own flaps and its own collision hull, described by one Data Asset.

Three ship with the template: DA_Box_Small, DA_Box_Medium, DA_Box_Large.

The recipe

  1. Model the box at its real size, with body, front flap and back flap as separate pieces, and export it.
  2. Import the meshes into Meshes/Props/Boxes/.
  3. Create a DA_Box_<Size> in Blueprints/DataAssets/Boxes/Childs/.
  4. Fill it in with the measurements from the model.
  5. Duplicate BP_DeliveryBox_Medium into Environments/Boxes/Childs/, rename it, and set its Size to your new asset. That is all the child does.
  6. Add your DA_Box_* to BoxSizes on BP_DeliveryManager, in the game state's Details panel, so deliveries can pick it.

The fields

Field What it does
BodyMesh The carton
FlapMesh The back flap
FlapLabelMesh The front flap, the one that carries the docket
FlapHingeYCm Where the flaps hinge, across the box
FlapHingeZCm Where the flaps hinge, up the box
InteriorMinCm The inside corner, in the box's local space
InteriorSizeCm The usable interior volume

InteriorSizeCm is the one that decides how many units a box holds, against the product's footprint, stack height and StackMax.

Measure the inside of the mesh, not the outside. A box measured on its outer face holds units that stick through the cardboard.

The docket

The white docket and the product icon sit on the front flap, positioned as components on the child Blueprint rather than as fields on the Data Asset, because where the label goes depends on how the mesh was modelled.

If the icon comes out on the wrong side after an import, it is the FBX export flipping Y. X and Z survive the trip, Y comes out mirrored.

Two traps

InitialUnits cannot exceed the real capacity. Set it higher and the extra units are dropped with no warning. If a delivery of one case comes up short, UnitsPerCase on the product is too high or the largest box is too small.

A box already placed in a level does not gain components you add afterwards. Delete the placed actor and place a fresh one. Same for new variables on a parent class: they come out empty on children that were already compiled.

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