unreal-python-scripting

Unreal Python Scripting

Version: 2.0.3 Last Updated: 2026-10-09 Target: Unreal Engine 5.8+ Dependencies: unreal Python module (built-in), UE 5.8 native MCP (HTTP, port 8000)

Preflight first (2026-09-08): before the first build step of any approved plan, run the unreal-project-preflight skill (ue_preflight.py --live --features <list> --plan-block) so plugins and project settings this skill depends on are enabled in ONE restart. Mid-task "class not found / plugin not enabled" errors go back to that Step 0, never to a runtime toggle.

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MCP Execution

All Python code runs via mcp__ue58-mcp__execute_python_code(code=...) which executes directly in the UE editor process. VibeUE toolsets are also available via mcp__ue58-mcp__call_tool(toolset_name=..., tool_name=..., arguments={...}).

Use mcp__ue58-mcp__discover_python_module(module_name="unreal") to introspect available Python API.

• An execute call times out at about 30 s ("Python execution exceeded 30000ms") while the script keeps running in the editor. Split long work into short calls, and after a timeout read the state back instead of re-running - a timeout is not a failure.

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Quick Start

Spawn Blueprint Actor

import unreal

# Load Blueprint (_C suffix required!)
bp = unreal.load_class(None, "/Game/BP_Actor.BP_Actor_C")

# Spawn
actor = unreal.EditorLevelLibrary.spawn_actor_from_class(
    bp, location=unreal.Vector(0, 0, 100)
)

# Access component
comps = actor.get_components_by_class(unreal.StaticMeshComponent)
if comps:
    comps[0].set_editor_property('mobility', unreal.ComponentMobility.MOVABLE)

Create Material Instance

import unreal

# Load master
master = unreal.load_asset("/Game/Materials/M_Master")

# Create instance
tools = unreal.AssetToolsHelpers.get_asset_tools()
instance = tools.create_asset(
    "MI_Shot001", "/Game/Materials/Instances",
    unreal.MaterialInstanceConstant,
    unreal.MaterialInstanceConstantFactoryNew()
)

# Set parent
instance.set_editor_property('parent', master)

# Override parameters
unreal.MaterialEditingLibrary.set_material_instance_texture_parameter_value(
    instance, 'BaseColor', unreal.load_asset("/Game/Textures/T_Tex")
)
unreal.MaterialEditingLibrary.set_material_instance_scalar_parameter_value(
    instance, 'Opacity', 1.0
)