Unity Terrain

Unity Terrain Skills

Guardrails

Operating Mode (v1.9 three-tier):

• Approval (default): query skills (terrain_get_info, terrain_get_height) run directly. Create/modify skills (terrain_create, terrain_set_height, terrain_set_heights_batch, terrain_add_hill, terrain_generate_perlin, terrain_smooth, terrain_flatten, terrain_paint_texture) are FullAuto — on MODE_RESTRICTED, run the grant protocol; /permission/grant executes the skill server-side and returns the result.
• Auto / Bypass: SemiAuto and FullAuto run directly.
• This module contains no Delete / PlayMode / Reload / RiskLevel="high" skills — nothing auto-classifies as forbidden. To remove a terrain delete the asset via asset_delete (subject to its own forbidden rules).

> Note: All sculpt/paint operations require an existing Terrain in the scene, or use terrain_create to generate one.

DO NOT (common hallucinations):

• terrain_set_texture does not exist → use terrain_paint_texture with layer index and brush parameters
• terrain_add_tree / terrain_add_grass do not exist → these require Unity Terrain tools or custom scripts
• terrain_set_size does not exist → terrain dimensions are set at creation via terrain_create
• terrain_import_heightmap / terrain_set_heights do not exist → use terrain_set_heights_batch with a 2D heights array ([z][x] values 0-1)

Routing:

• For terrain material → use material module on terrain's material
• For objects on terrain → use gameobject module to create/place objects

Skills Overview

| Skill | Description |

|-------|-------------|

| terrain_create | Create new Terrain with TerrainData |

| terrain_get_info | Get terrain size, resolution, layers |

| terrain_get_height | Get height at world position |

| terrain_set_height | Set height at normalized coords |

| terrain_set_heights_batch | Batch set heights in region |

| terrain_add_hill | ⭐ Add smooth hill with radius and falloff |

| terrain_generate_perlin | ⭐ Generate natural terrain using Perlin noise |

| terrain_smooth | ⭐ Smooth terrain to reduce sharp edges |

| terrain_flatten | ⭐ Flatten terrain to target height |

| terrain_paint_texture | Paint texture layer at position |

Skills

terrain_create

Create a new Terrain GameObject with TerrainData asset.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| name | string | No | "Terrain" | Terrain name |

| width | int | No | 500 | Terrain width (X) |

| length | int | No | 500 | Terrain length (Z) |

| height | int | No | 100 | Max terrain height (Y) |

| heightmapResolution | int | No | 513 | Heightmap resolution (power of 2 + 1) |

| x, y, z | float | No | 0 | Position |

Returns: {success, name, instanceId, terrainDataPath, size, position}

terrain_get_info

Get terrain information.

| Parameter | Type | Required | Description |

|-----------|------|----------|-------------|

| name | string | No* | Terrain name |

| instanceId | int | No* | Instance ID |

*If neither provided, uses first terrain in scene

Returns: {success, name, instanceId, position, size, heightmapResolution, alphamapResolution, detailResolution, terrainLayerCount, layers}

terrain_get_height

Get terrain height at world position.

| Parameter | Type | Required | Description |

|-----------|------|----------|-------------|

| worldX | float | Yes | World X coordinate |

| worldZ | float | Yes | World Z coordinate |

| name | string | No | Terrain name |

Returns: {success, worldX, worldZ, height, worldY}

terrain_set_height

Set height at normalized coordinates.

| Parameter | Type | Required | Description |

|-----------|------|----------|-------------|

| normalizedX | float | Yes | X position (0-1) |

| normalizedZ | float | Yes | Z position (0-1) |

| height | float | Yes | Height value (0-1) |

| name | string | No | Terrain name |

| instanceId | int | No | Terrain instance ID |

Returns: {success, normalizedX, normalizedZ, height, pixelX, pixelZ}

terrain_set_heights_batch

⚠️ BATCH SKILL: Set heights in rectangular region.

| Parameter | Type | Required | Description |

|-----------|------|----------|-------------|

| startX | int | Yes | Start X pixel index |

| startZ | int | Yes | Start Z pixel index |

| heights | float[][] | Yes | 2D array [z][x] with values 0-1 |

| name | string | No | Terrain name |

| instanceId | int | No | Terrain instance ID |

Returns: {success, startX, startZ, modifiedWidth, modifiedLength, totalPointsModified}

# Example: Create a 10x10 hill
heights = [[0.5 - abs(x-5)/10 - abs(z-5)/10 for x in range(10)] for z in range(10)]
call_skill("terrain_set_heights_batch", startX=50, startZ=50, heights=heights)

terrain_add_hill

⭐ RECOMMENDED: Add a smooth, natural-looking hill to the terrain.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| normalizedX | float | Yes | - | X position (0-1) |

| normalizedZ | float | Yes | - | Z position (0-1) |

| radius | float | No | 0.2 | Hill radius (0-1, relative to terrain size) |

| height | float | No | 0.5 | Hill height (0-1) |

| smoothness | float | No | 1.0 | Smoothness factor (higher = smoother) |

| name | string | No | null | Terrain name |

| instanceId | int | No | 0 | Terrain instance ID |

Returns: {success, centerX, centerZ, radius, height, affectedArea}

# Add a large smooth hill at center
call_skill("terrain_add_hill",
    normalizedX=0.5, normalizedZ=0.5,
    radius=0.3, height=0.6, smoothness=2.0)

# Add multiple hills for varied terrain
for i in range(5):
    call_skill("terrain_add_hill",
        normalizedX=random.uniform(0.2, 0.8),
        normalizedZ=random.uniform(0.2, 0.8),
        radius=random.uniform(0.1, 0.25),
        height=random.uniform(0.3, 0.7))

terrain_generate_perlin

⭐ RECOMMENDED: Generate natural-looking terrain using Perlin noise algorithm.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| scale | float | No | 20.0 | Noise scale (lower = larger features) |

| heightMultiplier | float | No | 0.3 | Height intensity (0-1) |

| octaves | int | No | 4 | Detail layers (more = more detail) |

| persistence | float | No | 0.5 | Amplitude decrease per octave |

| lacunarity | float | No | 2.0 | Frequency increase per octave |

| seed | int | No | 0 | Random seed (0 = random) |

| name | string | No | null | Terrain name |

Returns: {success, resolution, scale, heightMultiplier, octaves, persistence, lacunarity, seed}

# Generate rolling hills
call_skill("terrain_generate_perlin",
    scale=25.0, heightMultiplier=0.4, octaves=4)

# Generate mountainous terrain
call_skill("terrain_generate_perlin",
    scale=15.0, heightMultiplier=0.6, octaves=6, persistence=0.6)

# Generate with specific seed for reproducibility
call_skill("terrain_generate_perlin",
    scale=20.0, heightMultiplier=0.5, seed=12345)

terrain_smooth

⭐ Smooth terrain heights to reduce sharp edges and create natural transitions.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| normalizedX | float | Yes | - | X position (0-1) |

| normalizedZ | float | Yes | - | Z position (0-1) |

| radius | float | No | 0.1 | Smoothing radius (0-1) |

| iterations | int | No | 1 | Number of smoothing passes |

| name | string | No | null | Terrain name |

| instanceId | int | No | 0 | Terrain instance ID |

Returns: {success, centerX, centerZ, radius, iterations, affectedArea}

# Smooth a specific area
call_skill("terrain_smooth",
    normalizedX=0.5, normalizedZ=0.5,
    radius=0.2, iterations=3)

terrain_flatten

⭐ Flatten terrain to a specific height in a region.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| normalizedX | float | Yes | - | X position (0-1) |

| normalizedZ | float | Yes | - | Z position (0-1) |

| targetHeight | float | No | 0.5 | Target height (0-1) |

| radius | float | No | 0.1 | Flatten radius (0-1) |

| strength | float | No | 1.0 | Flatten strength (0-1) |

| name | string | No | null | Terrain name |

| instanceId | int | No | 0 | Terrain instance ID |

Returns: {success, centerX, centerZ, targetHeight, radius, strength}

# Create a flat plateau
call_skill("terrain_flatten",
    normalizedX=0.5, normalizedZ=0.5,
    targetHeight=0.6, radius=0.15, strength=1.0)

terrain_paint_texture

Paint terrain texture layer. Requires terrain layers already configured.

| Parameter | Type | Required | Default | Description |

|-----------|------|----------|---------|-------------|

| normalizedX | float | Yes | - | X position (0-1) |

| normalizedZ | float | Yes | - | Z position (0-1) |

| layerIndex | int | Yes | - | Terrain layer index (0-based; use terrain_get_info to query available layers) |

| strength | float | No | 1.0 | Paint strength |

| brushSize | int | No | 10 | Brush size in pixels |

| name | string | No | null | Terrain name |

| instanceId | int | No | 0 | Terrain instance ID |

Returns: {success, layerIndex, layerName, centerX, centerZ, brushSize, strength}

Example Usage

import unity_skills

# === Method 1: Quick terrain with Perlin noise (RECOMMENDED) ===
# Create terrain
result = unity_skills.call_skill("terrain_create",
    name="MyTerrain", width=200, length=200, height=50)

# Generate natural terrain with Perlin noise
unity_skills.call_skill("terrain_generate_perlin",
    scale=20.0,           # Larger scale = bigger features
    heightMultiplier=0.4, # Height intensity
    octaves=5,            # More octaves = more detail
    persistence=0.5,
    lacunarity=2.0)

# === Method 2: Add individual smooth hills ===
# Create flat terrain
result = unity_skills.call_skill("terrain_create",
    name="HillyTerrain", width=200, length=200, height=50)

# Add multiple smooth hills
import random
for i in range(8):
    unity_skills.call_skill("terrain_add_hill",
        normalizedX=random.uniform(0.2, 0.8),
        normalizedZ=random.uniform(0.2, 0.8),
        radius=random.uniform(0.15, 0.3),
        height=random.uniform(0.3, 0.6),
        smoothness=1.5)  # Higher = smoother

# Smooth the entire terrain for natural transitions
unity_skills.call_skill("terrain_smooth",
    normalizedX=0.5, normalizedZ=0.5,
    radius=0.5, iterations=2)

# === Method 3: Create specific features ===
# Create a mountain
unity_skills.call_skill("terrain_add_hill",
    normalizedX=0.5, normalizedZ=0.5,
    radius=0.25, height=0.8, smoothness=2.0)

# Create a flat plateau on top
unity_skills.call_skill("terrain_flatten",
    normalizedX=0.5, normalizedZ=0.5,
    targetHeight=0.8, radius=0.1, strength=1.0)

# === Method 4: Manual height control (advanced) ===
import math
heights = []
for z in range(64):
    row = []
    for x in range(64):
        # Distance from center
        dx = (x - 32) / 32
        dz = (z - 32) / 32
        dist = math.sqrt(dx*dx + dz*dz)
        # Smooth hill with cosine falloff
        h = max(0, 0.5 * math.cos(dist * math.pi / 2)) if dist < 1 else 0
        row.append(h)
    heights.append(row)

unity_skills.call_skill("terrain_set_heights_batch",
    startX=100, startZ=100, heights=heights)

# Query height at world position
info = unity_skills.call_skill("terrain_get_height", worldX=100, worldZ=100)
print(f"Height at position: {info['height']}")

Workflow Integration

All terrain operations support workflow undo/redo:

# Start workflow session
unity_skills.call_skill("workflow_session_start", tag="Create Terrain")

# Create and modify terrain
unity_skills.call_skill("terrain_create", name="TestTerrain")
unity_skills.call_skill("terrain_generate_perlin", scale=20, heightMultiplier=0.5)
unity_skills.call_skill("terrain_add_hill", normalizedX=0.3, normalizedZ=0.3, radius=0.2)

# End session
unity_skills.call_skill("workflow_session_end")

# Later: Undo entire terrain creation
sessions = unity_skills.call_skill("workflow_session_list")
unity_skills.call_skill("workflow_session_undo", sessionId=sessions['sessions'][0]['sessionId'])

Exact Signatures

Exact names, parameters, defaults, and returns are defined by GET /skills/schema or unity_skills.get_skill_schema(), not by this file.