Function expandPrefab

src/world/prefab.ts:103–163

(
  registry: PrefabRegistry,
  prefabId: string,
  parentMatrix: Mat4,
  parentTint: Vec4Lit | null,
  parentTags: ReadonlyArray<string>,
  out: PrefabLeaf[],
  errors: string[],
  visited: Set<string>,
  pathPrefix: string,
)

// @param visited        Set of ancestor prefab ids, used for cycle detection.
// @param pathPrefix     Debug path for error messages, e.g. "world_root".
export function expandPrefab(
  registry: PrefabRegistry,
  prefabId: string,
  parentMatrix: Mat4,
  parentTint: Vec4Lit | null,
  parentTags: ReadonlyArray<string>,
  out: PrefabLeaf[],
  errors: string[],
  visited: Set<string>,
  pathPrefix: string,
): void {
  if (visited.has(prefabId)) {
    errors.push(
      'prefab cycle detected: ' + pathPrefix + ' -> ' + prefabId +
        ' (already in chain)',
    );
    return;
  }

  const prefab = registry.getPrefab(prefabId);
  if (!prefab) {
    errors.push('prefab not found: "' + prefabId + '" (referenced by ' + pathPrefix + ')');
    return;
  }

  visited.add(prefabId);

  for (let i = 0; i < prefab.children.length; i++) {
    const child = prefab.children[i];
    const childMatrix = mat4Multiply(parentMatrix, trsToMat4(child.transform));
    const childTint = child.tint !== null ? child.tint : parentTint;
    const childTags = mergeTags(parentTags, child.tags);
    const childPath = pathPrefix + '.' + child.id;

    if (child.modelRef !== null && child.modelRef.length > 0) {
      out.push({
        modelRef: child.modelRef,
        worldMatrix: childMatrix,
        tint: childTint,
        tags: childTags,
        sourcePath: childPath,
      });
    } else if (child.prefabRef !== null && child.prefabRef.length > 0) {
      expandPrefab(
        registry,
        child.prefabRef,
        childMatrix,
        childTint,
        childTags,
        out,
        errors,
        visited,
        childPath,
      );
    } else {
      errors.push('prefab child ' + childPath + ' has neither modelRef nor prefabRef');
    }
  }