Collision Configuration¶

ModularBuildingSystem uses collision channels for:

Building placement checks
Building queries
Structural support detection

It is recommended to create dedicated channels for the plugin to avoid interfering with project channels such as Visibility and WorldStatic.

1. Create Collision Channels¶

Open:

Edit → Project Settings → Engine → Collision

Object Channels¶

Name	Default Response	Purpose
`MBS_Building`	`Block`	Identifies buildings generated by the plugin.
`MBS_WorldSupport`	`Block`	Identifies terrain and permanent world support objects.

Trace Channels¶

Name	Default Response	Purpose
`MBS_Placement`	`Ignore`	Detects objects that block building placement.
`MBS_Support`	`Ignore`	Detects support relationships between buildings and between buildings and the world.

These names are recommendations only and can be changed to suit the project.

2. Create the Ghost Profile¶

Create the following Collision Profile:

MBS_Ghost

Recommended configuration:

Property	Recommended Value
`Collision Enabled`	`Query Only`
`Object Type`	`WorldDynamic`
Default Response	`Ignore`
`MBS_Building`	`Overlap`
`MBS_WorldSupport`	`Overlap`
`MBS_Placement`	`Overlap`
`MBS_Support`	`Overlap`

MBS_Ghost is used only for building previews. Final buildings should use the project's own Collision Profiles.

3. Configure Building Components¶

Building components generated by the plugin should use:

Object Type = MBS_Building

Recommended responses:

Channel	Recommended Response
`MBS_Placement`	`Block`
`MBS_Support`	`Block`
`Visibility`	`Block`
`Pawn`	Configure according to project requirements

The primary building collision components used by both HISM and Actor modes should use MBS_Building.

Decorative or effect components in an Actor that do not participate in building logic can ignore:

MBS_Placement
MBS_Support

4. Configure World Support¶

Objects that provide permanent support should use:

Object Type = MBS_WorldSupport

Configure the following responses:

Channel	Recommended Response
`MBS_Placement`	`Block`
`MBS_Support`	`Block`

Common world support objects include:

Landscape
Ground Static Meshes
Fixed platforms
Permanent level structures
Load-bearing rocks

Player-built foundations, walls, and roofs are still regular buildings. They should use MBS_Building, not MBS_WorldSupport.

5. Configure Plugin Settings¶

Open:

Edit → Project Settings → Building System

Configure:

Plugin Setting	Recommended Value
`Default Ghost Collision Profile`	`MBS_Ghost`
`Placement Obstacle Trace Channel`	`MBS_Placement`
`Building Object Channel`	`MBS_Building`
`World Support Object Channel`	`MBS_WorldSupport`
`Support Query Trace Channel`	`MBS_Support`

An individual Building Data Asset can override the default Ghost Collision Profile.

6. Channel Response Rules¶

Objects that should block building placement must use:

MBS_Placement = Block

Objects that should participate in structural support detection must use:

MBS_Support = Block

Objects that should not affect placement or support should use:

MBS_Placement = Ignore
MBS_Support = Ignore

For example, grass, particle effects, and purely decorative components can usually ignore both channels.

Note

Structural support is determined through collision relationships and does not depend on Socket snapping.

Sockets are used only to align building previews. A building placed without snapping can still participate in support detection as long as its collision relationships are valid.

For World Support Tags, exclusion Tags, and collapse settings, see Structural Support and Collapse.

Troubleshooting¶

Issue	What to Check
The Ghost passes through existing buildings	Check whether the building blocks `MBS_Placement`.
The Ghost is always invalid	Check whether unrelated objects are blocking `MBS_Placement`.
Buildings cannot be selected or queried	Check whether the building component uses `MBS_Building`.
Buildings cannot receive world support	Check whether the ground uses `MBS_WorldSupport` and blocks `MBS_Support`.
Support cannot propagate between buildings	Check whether both buildings block `MBS_Support`.
Decorative objects incorrectly participate in support	Check whether the decorative components ignore `MBS_Support`.
Some Actor components incorrectly participate in detection	Check each Primitive Component separately.

Configuration Checklist¶

After completing the configuration, confirm that:

The Ghost uses MBS_Ghost.
Building components use MBS_Building.
Permanent support objects use MBS_WorldSupport.
Placement obstacles block MBS_Placement.
Buildings and support objects block MBS_Support.
Decorative and effect components ignore unnecessary queries.
The plugin settings match the project's collision channels.