"""The Blender backend: real meshes, materials, text and the GLB export. Runs only inside Blender. Every object is named and lives in the collection of the `context()` that made it, so the saved .blend stays editable part by part. The GLB is the opposite: `export_glb` duplicates every mesh into a scratch collection, joins the copies per material (one draw call each) and exports only those — the named parts are untouched, which is why the .blend is saved BEFORE the export.""" from __future__ import annotations import math import os import bmesh import bpy from mathutils import Vector from bmlevel.core import blender_yaw, flat_to_points, to_blender class BpyScene: available = True def __init__(self) -> None: self.materials: dict[str, bpy.types.Material] = {} self._collection_stack: list[bpy.types.Collection] = [] self.reset() # ---- scene lifecycle -------------------------------------------------- def reset(self) -> None: bpy.ops.wm.read_factory_settings(use_empty=True) self.materials.clear() self._collection_stack.clear() bpy.context.preferences.filepaths.save_version = 0 @property def collection(self) -> bpy.types.Collection: return self._collection_stack[-1] if self._collection_stack else bpy.context.scene.collection def begin_collection(self, name: str) -> None: col = bpy.data.collections.new(name) self.collection.children.link(col) self._collection_stack.append(col) def end_collection(self) -> None: self._collection_stack.pop() # ---- materials -------------------------------------------------------- def material(self, name, rgb, metal, roughness, glow, alpha) -> None: m = bpy.data.materials.new(name) m.use_nodes = True m.use_backface_culling = alpha >= 1 p = m.node_tree.nodes['Principled BSDF'] p.inputs['Base Color'].default_value = (*rgb, 1) p.inputs['Metallic'].default_value = metal p.inputs['Roughness'].default_value = roughness p.inputs['Alpha'].default_value = alpha if glow: p.inputs['Emission Color'].default_value = (*rgb, 1) p.inputs['Emission Strength'].default_value = glow if alpha < 1: m.surface_render_method = 'BLENDED' m.diffuse_color = (*rgb, alpha) self.materials[name] = m def _mat(self, name: str) -> bpy.types.Material: if name not in self.materials: raise KeyError(f'material {name!r} was never declared — call mat({name!r}, (r, g, b)) first') return self.materials[name] # ---- meshes ----------------------------------------------------------- def _add_mesh(self, name: str, verts, faces, material: str) -> bpy.types.Object: mesh = bpy.data.meshes.new(name) mesh.from_pydata(verts, [], faces) mesh.update() obj = bpy.data.objects.new(name, mesh) self.collection.objects.link(obj) obj.data.materials.append(self._mat(material)) return obj def box(self, name, world_pos, size, world_yaw, material, bevel) -> None: w, h, d = (float(s) for s in size) hx, hy, hz = w / 2, d / 2, h / 2 # Blender x = game x, Blender y = -game z (depth), Blender z = game y verts = [(-hx, -hy, -hz), (hx, -hy, -hz), (hx, hy, -hz), (-hx, hy, -hz), (-hx, -hy, hz), (hx, -hy, hz), (hx, hy, hz), (-hx, hy, hz)] faces = [(0, 3, 2, 1), (4, 5, 6, 7), (0, 1, 5, 4), (1, 2, 6, 5), (2, 3, 7, 6), (3, 0, 4, 7)] obj = self._add_mesh(name, verts, faces, material) obj.location = to_blender(world_pos) obj.rotation_euler = (0.0, 0.0, blender_yaw(world_yaw)) if bevel: bm = bmesh.new() bm.from_mesh(obj.data) bmesh.ops.bevel(bm, geom=list(bm.edges), offset=min(bevel, min(w, h, d) / 2.5), segments=2, affect='EDGES', clamp_overlap=True) bm.to_mesh(obj.data) bm.free() obj.data.update() def prism(self, name, world_vertices, material) -> None: pts = flat_to_points(world_vertices) n = len(pts) // 2 verts = [to_blender(p) for p in pts] faces = [tuple(reversed(range(n))), tuple(range(n, 2 * n))] + [(i, (i + 1) % n, (i + 1) % n + n, i + n) for i in range(n)] self._add_mesh(name, verts, faces, material) def hull(self, name, world_vertices, material) -> None: bm = bmesh.new() for p in flat_to_points(world_vertices): bm.verts.new(to_blender(p)) bm.verts.ensure_lookup_table() res = bmesh.ops.convex_hull(bm, input=list(bm.verts)) bmesh.ops.delete(bm, geom=[g for g in res['geom_interior'] if isinstance(g, bmesh.types.BMVert)], context='VERTS') mesh = bpy.data.meshes.new(name) bm.to_mesh(mesh) bm.free() mesh.update() obj = bpy.data.objects.new(name, mesh) self.collection.objects.link(obj) obj.data.materials.append(self._mat(material)) def text(self, name, string, world_pos, world_yaw, size, material, extrude, both_faces) -> None: faces = [world_yaw, world_yaw + math.pi] if both_faces else [world_yaw] for i, yaw in enumerate(faces): curve = bpy.data.curves.new(f'{name}-{i}', type='FONT') # Blender's bundled Bfont — no font file needed curve.body = string curve.size = size curve.extrude = extrude curve.align_x = 'CENTER' obj = bpy.data.objects.new(name if i == 0 else f'{name} (reverse)', curve) self.collection.objects.link(obj) obj.location = to_blender(world_pos) # A FONT lies in Blender XY facing +Z; stand it up so it faces game +Z at yaw 0, then yaw it. obj.rotation_euler = (math.pi / 2, 0.0, blender_yaw(yaw) + math.pi) obj.data.materials.append(self._mat(material)) bpy.context.view_layer.objects.active = obj obj.select_set(True) bpy.ops.object.convert(target='MESH') obj.select_set(False) # ---- output ----------------------------------------------------------- def save_blend(self, path: str) -> None: os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True) bpy.ops.wm.save_as_mainfile(filepath=os.path.abspath(path)) def export_glb(self, path: str) -> int: """Join duplicates per material and export those alone; the named parts stay as they are.""" scratch = bpy.data.collections.new('__export__') bpy.context.scene.collection.children.link(scratch) by_material: dict[str, list[bpy.types.Object]] = {} for obj in list(bpy.data.objects): if obj.type != 'MESH' or obj.users_collection[0] is scratch: continue copy = obj.copy() copy.data = obj.data.copy() scratch.objects.link(copy) key = obj.data.materials[0].name if obj.data.materials else '__none__' by_material.setdefault(key, []).append(copy) bpy.ops.object.select_all(action='DESELECT') joined: list[bpy.types.Object] = [] for key, objs in by_material.items(): for o in objs: o.select_set(True) bpy.context.view_layer.objects.active = objs[0] if len(objs) > 1: bpy.ops.object.join() active = bpy.context.view_layer.objects.active active.name = f'Level_{key}' joined.append(active) bpy.ops.object.select_all(action='DESELECT') for o in joined: o.select_set(True) os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True) bpy.ops.export_scene.gltf( filepath=os.path.abspath(path), export_format='GLB', use_selection=True, export_apply=True, export_yup=True, export_lights=False, export_cameras=False, export_materials='EXPORT', ) for o in joined: bpy.data.objects.remove(o, do_unlink=True) bpy.data.collections.remove(scratch) return os.path.getsize(path)