rbx-reader-rts/src/utils.ts

A modern TypeScript library for parsing Roblox binary files (.rbxm, .rbxl) in Node.js and the browser. Provides utilities to extract Animation and Sound asset IDs and is easily extensible.

import Instance, { InstanceRoot } from './Instance';

/**
 * Update all AnimationId properties in the given instance tree according to
 * the provided mapping.  Each key in the mapping corresponds to an old
 * animation ID (as a string or number), and its value is the new ID.  Any
 * instance that has an AnimationId property matching one of the keys will
 * have its AnimationId replaced with `rbxassetid://<newId>`.
 *
 * @param root The root instance tree to traverse.
 * @param mapping A map of old IDs to new IDs (string or number).
 */
export function updateAnimationIds(root: InstanceRoot, mapping: Record<string, string | number>): void {
  function traverse(inst: Instance) {
    // Check if this instance has a property that looks like an animation ID.
    for (const prop in inst.Properties) {
      const lower = prop.toLowerCase();
      if (lower.includes('animationid')) {
        const desc = inst.Properties[prop];
        const value = desc?.value;
        if (typeof value === 'string') {
          // Extract numeric part
          const match = value.match(/\d{3,}/);
          if (match) {
            const oldId = match[0];
            const newId = mapping[oldId];
            if (newId !== undefined) {
              // Update property value via descriptor
              inst.Properties[prop].value = `rbxassetid://${newId}`;
            }
          }
        }
      }
    }
    // Special case: Animation class with direct AnimationId property
    if (inst.ClassName.toLowerCase() === 'animation') {
      const val: any = (inst as any).AnimationId;
      if (typeof val === 'string') {
        const match = val.match(/\d{3,}/);
        if (match) {
          const oldId = match[0];
          const newId = mapping[oldId];
          if (newId !== undefined) {
            (inst as any).AnimationId = `rbxassetid://${newId}`;
          }
        }
      }
    }
    // Traverse children
    inst.Children.forEach(child => traverse(child));
  }
  root.getChildren().forEach(child => traverse(child));
}