Landscape Materials

🧠 Brains complement: IF an unreal-engine-skills-manager tool (external MCP) exists in this session, call it with {action: "load", skill: "materials-and-shaders"} for UE domain knowledge on this topic — correct APIs, architecture, best practices — and treat it as the rubric for any review / "best practices" question. If no such tool is available (e.g. running under Claude Code or Codex without that MCP), skip this line entirely and proceed with this skill alone — do NOT attempt the call.

Landscape Material System Skill

When to Use This Skill vs. landscape-auto-material

• This skill (landscape-materials): Simple materials with 2-5 layers using LandscapeLayerBlend. Good for prototyping.
• landscape-auto-material: Production materials using material functions, RVT, and material instances. Good for shipping quality. Use when you need the Real_Landscape paradigm with auto-layering, altitude/slope blending via material functions, and biome configuration through material instances.

If you need material functions, Runtime Virtual Textures, or the master-material + instance pattern, load the landscape-auto-material skill (the engine's AgentSkillToolset GetSkills exposes it).

Critical Rules

🚨 Inspect Before Modifying Existing Landscape Materials

Before modifying an existing landscape material, you MUST export and review its current graph:

import unreal, json

path = "/Game/Materials/M_Terrain"

# Step 1: Get material info
info = unreal.MaterialService.get_material_info(path)
print(f"Blend: {info.blend_mode}, Shading: {info.shading_model}")

# Step 2: Export full graph to see what nodes and connections already exist
graph = json.loads(unreal.MaterialNodeService.export_material_graph(path))
for expr in graph['expressions']:
    name = expr.get('parameter_name') or expr.get('class')
    print(f"  [{expr['id']}] {expr['class']} - {name}")
    if expr.get('landscape_layers'):
        for layer in expr['landscape_layers']:
            print(f"      Layer: {layer}")
for oc in graph['output_connections']:
    print(f"  Output '{oc['property']}' ← expr {oc['expression_id']}")

Why: Landscape materials often already have LayerBlend nodes, texture samplers, and connected outputs. Adding duplicate nodes without reviewing first creates orphaned expressions and broken connections. Always export → review → plan → modify.

Two Services Work Together

• LandscapeMaterialService - Landscape-specific nodes (LayerBlend, LayerCoords, LayerInfo)
• MaterialService + MaterialNodeService - Standard material operations (create, compile, save, connect other nodes)

Layer Blend Types

Always Create Layer Info Objects

Each layer name needs a matching ULandscapeLayerInfoObject asset:

• Create before assigning material to landscape
• Asset name convention: LI_<LayerName> (e.g., LI_Grass, LI_Rock)
• ALWAYS store and use .asset_path from create_layer_info_object() result — never guess paths
• WRONG: "/Game/Landscape/Grass_LayerInfo" → CORRECT: grass_info.asset_path (which is "/Game/Landscape/LI_Grass")

⚠️ assign_material_to_landscape Will Silently Skip Bad Paths

If layer_info_paths contains wrong paths, assign_material_to_landscape may return True (material set) but layers will be empty. Always verify with get_landscape_info().layers after assignment.

Compile + Save After Changes

unreal.MaterialService.compile_material(mat_path)
unreal.EditorAssetLibrary.save_asset(mat_path)

⚠️ compile_material Is Slow — Use Separate Code Blocks

compile_material() can take minutes for landscape materials with blend nodes. NEVER put create + compile in the same code block — it will exceed the Python execution timeout.

Split into separate steps:

1. Block 1: Create material, add blend nodes, add layers, connect outputs, save
2. Block 2: compile_material(mat_path) alone
3. Block 3: Create layer info objects, assign to landscape

Texture Tiling

• Landscapes are large; textures need tiling via LandscapeLayerCoords
• Default MappingScale=0.01 tiles every 100 units
• Smaller values = more tiling, larger values = less tiling

Task Index

Sub-docs

• workflows.md — step-by-step landscape-material build workflows (layers, textures, layer info, grass).
• satellite.md — satellite-image-guided material creation and slope/height painting.

Verification

compile_material (slow — keep it in its own code block) then save. Inspect the graph with MaterialNodeService.export_material_graph before modifying an existing landscape material.

Sample scripts (run via execute_python_code)

• scripts/create_landscape_material.txt — create a landscape material with a layer blend, compile, assign.