253 lines
11 KiB
Python
253 lines
11 KiB
Python
"""Shared by generate_procedural_terrain.py and generate_terrain_from_heightmap.py.
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Everything here is agnostic to where the height values come from - it only
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needs a "field" object with:
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field.height(x, y) -> float
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field.normal(x, y) -> unreal.Vector (unit length)
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so noise-driven and heightmap-driven terrains can reuse the exact same mesh
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building, ground-snapping, and scatter/placement logic.
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"""
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import math, random, unreal
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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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def finite_difference_normal(height_fn, x, y, step=200.0):
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"""Surface normal from four height samples around (x, y). `step` should be
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large enough to average over small-scale bumps - otherwise high-frequency
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noise/heightmap detail produces exaggerated per-instance tilt."""
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h_l = height_fn(x - step, y)
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h_r = height_fn(x + step, y)
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h_d = height_fn(x, y - step)
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h_u = height_fn(x, y + step)
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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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is_masked = getattr(field, "is_masked", None)
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if is_masked is not None:
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masked_vertex_ids = {vid for vid, p in enumerate(positions) if is_masked(p.x, p.y)}
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if masked_vertex_ids:
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mesh, triangle_list, _has_tri_gaps = unreal.GeometryScript_MeshQueries.get_all_triangle_indices(mesh, False)
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triangles = unreal.GeometryScript_List.convert_triangle_list_to_array(triangle_list)
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triangles_to_delete = [
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tid for tid, tri in enumerate(triangles)
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if tri.x in masked_vertex_ids or tri.y in masked_vertex_ids or tri.z in masked_vertex_ids
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]
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if triangles_to_delete:
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index_list = unreal.GeometryScript_List.convert_array_to_index_list(triangles_to_delete)
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mesh, num_deleted = unreal.GeometryScript_MeshEdits.delete_triangles_from_mesh(mesh, index_list)
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print(f" cut {num_deleted} triangle(s) out of masked/transparent regions")
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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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asset_path = f"{dest_path}/{asset_name}"
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if unreal.EditorAssetLibrary.does_asset_exist(asset_path):
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unreal.EditorAssetLibrary.delete_asset(asset_path)
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create_options = unreal.GeometryScriptCreateNewStaticMeshAssetOptions()
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static_mesh, _outcome = unreal.GeometryScript_NewAssetUtils.create_new_static_mesh_asset_from_mesh(
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mesh, asset_path, create_options,
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)
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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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def spawn_terrain_actor(static_mesh, origin, base_folder, label):
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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(base_folder)
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terrain_actor.set_actor_label(label)
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return terrain_actor
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# ---------------------------------------------------------------------------
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# Ground-snapping / alignment ------------------------------------------------
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# ---------------------------------------------------------------------------
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_mesh_bounds_cache = {}
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def mesh_local_bounds(mesh):
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path = mesh.get_path_name()
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if path not in _mesh_bounds_cache:
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box = mesh.get_bounding_box()
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_mesh_bounds_cache[path] = (box.min, box.max)
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return _mesh_bounds_cache[path]
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def ground_offset_for(mesh, quat, scale_vec):
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"""World-space Z distance from the actor's pivot down to the lowest point of
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its (scaled, rotated) mesh, so the base can be planted exactly on the ground
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no matter where the source asset's pivot was authored, or how it's tilted."""
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box_min, box_max = mesh_local_bounds(mesh)
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min_z = None
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for x in (box_min.x, box_max.x):
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for y in (box_min.y, box_max.y):
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for z in (box_min.z, box_max.z):
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corner = unreal.Vector(x * scale_vec.x, y * scale_vec.y, z * scale_vec.z)
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world_z = quat.rotate_vector(corner).z
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if min_z is None or world_z < min_z:
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min_z = world_z
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return -min_z
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def align_and_yaw_quat(normal, yaw_degrees, align_to_normal):
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"""Random yaw about the object's own up axis, then (optionally) tilt that
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up axis to match the terrain normal - in that order, since tilting first
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would rotate the yaw axis out from under the random spin."""
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yaw_quat = unreal.Rotator(roll=0.0, pitch=0.0, yaw=yaw_degrees).quaternion()
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if not align_to_normal:
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return yaw_quat
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align_quat = unreal.Vector(0.0, 0.0, 1.0).find_quat_between_normals(normal)
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return align_quat * yaw_quat
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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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is_masked = getattr(field, "is_masked", None)
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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 is_masked is not None and is_masked(x, y):
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continue
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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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scale = rng.uniform(layer_cfg["min_scale"], layer_cfg["max_scale"])
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scale_vec = unreal.Vector(scale, scale, scale)
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yaw = rng.uniform(0.0, 360.0)
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quat = align_and_yaw_quat(normal, yaw, layer_cfg.get("align_to_normal", False))
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rotation = quat.rotator()
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ground_offset = ground_offset_for(mesh, quat, scale_vec)
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location = unreal.Vector(origin.x + x, origin.y + y, origin.z + z + ground_offset)
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actor = actor_subsystem.spawn_actor_from_object(mesh, location, rotation)
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actor.set_actor_scale3d(scale_vec)
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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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def place_explicit(entries, field, origin, base_folder):
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"""Places an exact, hand-authored (or externally-generated) list of instances.
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Unlike scatter_layer's density/slope rules, this reproduces a literal
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manifest byte-for-byte: the same JSON always yields the same named
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landmarks at the same coordinates - useful for hero props, quest markers,
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or a layout exported from an external design tool, none of which a
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rule-driven scatter (ours or a graph-based tool like PCG) is meant to pin down.
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"""
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is_masked = getattr(field, "is_masked", None)
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placed = 0
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for entry in entries:
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mesh = unreal.load_asset(entry["mesh"])
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if mesh is None:
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print(f" [explicit] missing mesh asset: {entry['mesh']}")
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continue
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x, y, z_offset = entry.get("location", [0.0, 0.0, 0.0])
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if is_masked is not None and is_masked(x, y):
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print(f" [explicit] {entry.get('name', '?')} falls in a masked/transparent region, skipping")
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continue
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scale = entry.get("scale", 1.0)
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if isinstance(scale, list):
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scale_vec = unreal.Vector(*scale)
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else:
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scale_vec = unreal.Vector(scale, scale, scale)
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roll, pitch, yaw = entry.get("rotation", [0.0, 0.0, 0.0])
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rotation = unreal.Rotator(roll=roll, pitch=pitch, yaw=yaw)
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quat = rotation.quaternion()
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z = z_offset
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if entry.get("snap_to_terrain", True):
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z += field.height(x, y) + ground_offset_for(mesh, quat, scale_vec)
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location = unreal.Vector(origin.x + x, origin.y + y, origin.z + z)
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actor = actor_subsystem.spawn_actor_from_object(mesh, location, rotation)
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actor.set_actor_scale3d(scale_vec)
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actor.set_folder_path(f"{base_folder}/Explicit")
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actor.set_actor_label(entry.get("name", f"Explicit_{placed:04d}"))
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placed += 1
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print(f" [explicit] placed {placed}/{len(entries)}")
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return placed
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