227 lines
9.0 KiB
Python
227 lines
9.0 KiB
Python
"""Run inside Unreal (Python console / Execute Python Script).
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Reads terrain_config.json (next to this script) and:
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1. builds a heightfield mesh with GeometryScript (fractal value noise),
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bakes it to a StaticMesh, and drops it into the level;
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2. scatters tree/rock StaticMeshActors across it per "scatter_layers",
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using the same noise field so foliage height always matches the
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ground beneath it (no raycasting needed).
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Run import_environment_assets.py first so the mesh paths referenced in
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terrain_config.json actually exist.
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"""
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import os, json, math, random, unreal
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CONFIG_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "terrain_config.json")
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asset_tools = unreal.AssetToolsHelpers.get_asset_tools()
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actor_subsystem = unreal.get_editor_subsystem(unreal.EditorActorSubsystem)
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# ---------------------------------------------------------------------------
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# Fractal value noise (pure Python, no engine dependency) -------------------
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# ---------------------------------------------------------------------------
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class ValueNoise2D:
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"""Seeded, smooth, tileable-enough value noise for terrain-style height fields."""
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def __init__(self, seed):
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rng = random.Random(seed)
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table = list(range(256))
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rng.shuffle(table)
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self._perm = table + table # avoid overflow when indexing i+1
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@staticmethod
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def _fade(t):
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return t * t * t * (t * (t * 6 - 15) + 10)
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@staticmethod
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def _lerp(a, b, t):
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return a + t * (b - a)
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def _gradient(self, ix, iy):
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h = self._perm[(self._perm[ix & 255] + iy) & 255]
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angle = (h / 255.0) * 2.0 * math.pi
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return math.cos(angle), math.sin(angle)
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def sample(self, x, y):
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x0, y0 = math.floor(x), math.floor(y)
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x1, y1 = x0 + 1, y0 + 1
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sx, sy = x - x0, y - y0
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def dot_grid(ix, iy, px, py):
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gx, gy = self._gradient(ix, iy)
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return gx * (px - ix) + gy * (py - iy)
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n00 = dot_grid(x0, y0, x, y)
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n10 = dot_grid(x1, y0, x, y)
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n01 = dot_grid(x0, y1, x, y)
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n11 = dot_grid(x1, y1, x, y)
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u, v = self._fade(sx), self._fade(sy)
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return self._lerp(self._lerp(n00, n10, u), self._lerp(n01, n11, u), v)
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class FractalHeightField:
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def __init__(self, noise_cfg, height_scale):
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self.height_scale = height_scale
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self.frequency = noise_cfg["frequency"]
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self.octaves = noise_cfg["octaves"]
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self.lacunarity = noise_cfg["lacunarity"]
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self.gain = noise_cfg["gain"]
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self.noise = ValueNoise2D(noise_cfg["seed"])
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def height(self, x, y):
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amplitude, frequency, total, max_amp = 1.0, self.frequency, 0.0, 0.0
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for _ in range(self.octaves):
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total += amplitude * self.noise.sample(x * frequency, y * frequency)
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max_amp += amplitude
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amplitude *= self.gain
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frequency *= self.lacunarity
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return (total / max_amp) * self.height_scale
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def normal(self, x, y, step=25.0):
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h_l = self.height(x - step, y)
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h_r = self.height(x + step, y)
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h_d = self.height(x, y - step)
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h_u = self.height(x, y + step)
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# tangents along X and Y, cross product gives the surface normal.
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tangent_x = unreal.Vector(2 * step, 0.0, h_r - h_l)
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tangent_y = unreal.Vector(0.0, 2 * step, h_u - h_d)
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nx = tangent_x.y * tangent_y.z - tangent_x.z * tangent_y.y
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ny = tangent_x.z * tangent_y.x - tangent_x.x * tangent_y.z
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nz = tangent_x.x * tangent_y.y - tangent_x.y * tangent_y.x
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length = math.sqrt(nx * nx + ny * ny + nz * nz) or 1.0
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return unreal.Vector(nx / length, ny / length, nz / length)
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# ---------------------------------------------------------------------------
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# Terrain mesh ----------------------------------------------------------------
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# ---------------------------------------------------------------------------
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def build_terrain_mesh(cfg, field):
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steps = max(2, cfg["resolution"])
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mesh = unreal.DynamicMesh()
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primitive_options = unreal.GeometryScriptPrimitiveOptions()
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mesh = unreal.GeometryScript_Primitives.append_rectangle_xy(
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mesh, primitive_options, unreal.Transform(),
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dimension_x=cfg["size_x"], dimension_y=cfg["size_y"],
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steps_width=steps, steps_height=steps,
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)
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mesh, position_list, _has_gaps = unreal.GeometryScript_MeshQueries.get_all_vertex_positions(mesh, False)
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positions = unreal.GeometryScript_List.convert_vector_list_to_array(position_list)
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min_x = min_y = float("inf")
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max_x = max_y = float("-inf")
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displaced = []
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for p in positions:
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z = field.height(p.x, p.y)
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displaced.append(unreal.Vector(p.x, p.y, z))
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min_x, max_x = min(min_x, p.x), max(max_x, p.x)
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min_y, max_y = min(min_y, p.y), max(max_y, p.y)
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new_list = unreal.GeometryScript_List.convert_array_to_vector_list(displaced)
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mesh = unreal.GeometryScript_MeshEdits.set_all_mesh_vertex_positions(mesh, new_list)
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mesh = unreal.GeometryScript_Normals.set_per_vertex_normals(mesh)
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dest_path = cfg["dest_path"]
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asset_name = cfg["asset_name"]
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if unreal.EditorAssetLibrary.does_asset_exist(f"{dest_path}/{asset_name}"):
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unreal.EditorAssetLibrary.delete_asset(f"{dest_path}/{asset_name}")
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static_mesh = asset_tools.create_asset(asset_name, dest_path, unreal.StaticMesh, unreal.StaticMeshFactoryNew())
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copy_options = unreal.GeometryScriptCopyMeshToAssetOptions()
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target_lod = unreal.GeometryScriptMeshWriteLOD()
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unreal.GeometryScript_AssetUtils.copy_mesh_to_static_mesh(mesh, static_mesh, copy_options, target_lod)
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unreal.EditorAssetLibrary.save_asset(static_mesh.get_path_name())
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bounds = (min_x, max_x, min_y, max_y)
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return static_mesh, bounds
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# ---------------------------------------------------------------------------
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# Foliage scatter --------------------------------------------------------------
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# ---------------------------------------------------------------------------
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def scatter_layer(layer_cfg, field, bounds, origin, base_folder):
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min_x, max_x, min_y, max_y = bounds
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rng = random.Random(layer_cfg.get("seed", 0))
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meshes = [unreal.load_asset(path) for path in layer_cfg["meshes"]]
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meshes = [m for m in meshes if m is not None]
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if not meshes:
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print(f" [{layer_cfg['name']}] no valid meshes found, skipping")
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return 0
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max_slope_cos = math.cos(math.radians(layer_cfg.get("max_slope_degrees", 90.0)))
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min_spacing = layer_cfg.get("min_spacing", 0.0)
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min_spacing_sqr = min_spacing * min_spacing
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placed_points = []
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spawned = 0
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max_attempts = layer_cfg["count"] * 25
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attempts = 0
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while spawned < layer_cfg["count"] and attempts < max_attempts:
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attempts += 1
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x = rng.uniform(min_x, max_x)
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y = rng.uniform(min_y, max_y)
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if min_spacing_sqr > 0.0 and any((x - px) ** 2 + (y - py) ** 2 < min_spacing_sqr for px, py in placed_points):
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continue
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z = field.height(x, y)
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if not (layer_cfg["min_height"] <= z <= layer_cfg["max_height"]):
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continue
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normal = field.normal(x, y)
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if normal.z < max_slope_cos:
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continue
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placed_points.append((x, y))
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mesh = rng.choice(meshes)
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location = unreal.Vector(origin.x + x, origin.y + y, origin.z + z)
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yaw = rng.uniform(0.0, 360.0)
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if layer_cfg.get("align_to_normal", False):
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# Approximate tilt from the surface normal; good enough for gentle slopes.
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pitch = -math.degrees(math.atan2(normal.x, normal.z))
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roll = math.degrees(math.atan2(normal.y, normal.z))
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rotation = unreal.Rotator(roll=roll, pitch=pitch, yaw=yaw)
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else:
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rotation = unreal.Rotator(roll=0.0, pitch=0.0, yaw=yaw)
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actor = actor_subsystem.spawn_actor_from_object(mesh, location, rotation)
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scale = rng.uniform(layer_cfg["min_scale"], layer_cfg["max_scale"])
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actor.set_actor_scale3d(unreal.Vector(scale, scale, scale))
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actor.set_folder_path(f"{base_folder}/{layer_cfg['name']}")
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actor.set_actor_label(f"{layer_cfg['name']}_{spawned:04d}")
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spawned += 1
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print(f" [{layer_cfg['name']}] placed {spawned}/{layer_cfg['count']} ({attempts} attempts)")
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return spawned
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# ---------------------------------------------------------------------------
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def main():
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with open(CONFIG_PATH, "r") as f:
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config = json.load(f)
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terrain_cfg = config["terrain"]
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field = FractalHeightField(terrain_cfg["noise"], terrain_cfg["height_scale"])
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print("Building terrain mesh...")
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static_mesh, bounds = build_terrain_mesh(terrain_cfg, field)
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loc = terrain_cfg["location"]
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origin = unreal.Vector(loc[0], loc[1], loc[2])
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terrain_actor = actor_subsystem.spawn_actor_from_object(static_mesh, origin, unreal.Rotator(0, 0, 0))
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terrain_actor.set_folder_path("ProceduralTerrain")
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terrain_actor.set_actor_label("ProceduralTerrain")
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print("Scattering foliage layers...")
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for layer_cfg in config.get("scatter_layers", []):
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scatter_layer(layer_cfg, field, bounds, origin, "ProceduralTerrain")
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print("Done.")
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main()
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