BabylonJS/Babylon.js · error · Error

Expected OFFSET, but got:

Error message

Expected OFFSET, but got:

What it means

Each BVH node's first line inside its brace must start with the keyword OFFSET. When the parser reads a line that is not OFFSET (it echoes the offending token into the message), it throws, because the required channel-offset declaration is missing or out of order.

Source

Thrown at packages/dev/loaders/src/BVH/bvhLoader.ts:271

    } else {
        node.name = tokens[1];
        node.type = tokens[0].toUpperCase();
    }

    // opening bracket
    if (lines.shift()?.trim() != "{") {
        throw new Error("Expected opening { after type & name");
    }

    // parse OFFSET
    const tokensSplit = lines.shift()?.trim().split(/\s+/);
    if (!tokensSplit) {
        throw new Error("Unexpected end of file: missing OFFSET");
    }
    tokens = tokensSplit;

    if (tokens[0].toUpperCase() != "OFFSET") {
        throw new Error("Expected OFFSET, but got: " + tokens[0]);
    }
    if (tokens.length != 4) {
        throw new Error("OFFSET: Invalid number of values");
    }

    const offset = new Vector3(parseFloat(tokens[1]), parseFloat(tokens[2]), parseFloat(tokens[3]));

    if (isNaN(offset.x) || isNaN(offset.y) || isNaN(offset.z)) {
        throw new Error("OFFSET: Invalid values");
    }

    node.offset = offset;

    // parse CHANNELS definitions
    if (node.type != "ENDSITE") {
        tokens = lines.shift()?.trim().split(/\s+/);
        if (!tokens) {
            throw new Error("Unexpected end of file: missing CHANNELS");

View on GitHub (pinned to 0592b347b8)

Solutions

  1. Open the .bvh and confirm each node body starts with "OFFSET x y z" before any CHANNELS line — move misplaced lines into position.
  2. Re-export the BVH from the source DCC/mocap tool instead of hand-editing.
  3. Check the reported offending token in the message to locate the bad line quickly.
  4. If a script transforms your BVH, fix its line ordering or validate output against the BVH spec.

Example fix

// before (malformed)
ROOT Hips
{
  CHANNELS 6 Xposition Yposition Zposition Zrotation Xrotation Yrotation
  OFFSET 0.0 0.0 0.0
// after (valid)
ROOT Hips
{
  OFFSET 0.0 0.0 0.0
  CHANNELS 6 Xposition Yposition Zposition Zrotation Xrotation Yrotation
Defensive patterns

Strategy: validation

Validate before calling

function assertOffsetFirstInsideNodes(text: string): void {
  const lines = text.split(/\r?\n/).map((l) => l.trim());
  let expectOffset = false;
  lines.forEach((line, i) => {
    const t = line.toUpperCase();
    if (/^(ROOT|JOINT)\s/.test(t) || t === "END SITE") { expectOffset = true; return; }
    if (expectOffset) {
      if (line !== "{") throw new Error(`Line ${i + 1}: expected {`);
      expectOffset = false;
      // next non-brace line must be OFFSET
      const next = lines[i + 1];
      if (next && !next.toUpperCase().startsWith("OFFSET")) {
        throw new Error(`Line ${i + 2}: expected OFFSET, got "${next.split(/\s+/)[0]}"`);
      }
    }
  });
}

Try / catch

try {
  const skeleton = ReadBvh(text, scene, null, options);
} catch (e) {
  if (e instanceof Error && e.message.startsWith("Expected OFFSET")) {
    console.error("BVH node body is out of order: OFFSET must come first inside each node.");
  } else { throw e; }
}

Prevention

When it happens

Trigger: A node body where CHANNELS, JOINT, "}", or any other token appears before OFFSET; swapped lines such as "CHANNELS 6 Xrotation ..." placed before OFFSET; a name line accidentally pasted inside the node body.

Common situations: Hand-edited BVH files with reordered lines; exports from custom/buggy tooling that writes CHANNELS before OFFSET; line-alignment drift when files are processed by scripts that re-sort or dedent lines.

Related errors

AI-assisted analysis of BabylonJS/Babylon.js@0592b347b8 (2026-08-30). Data as JSON: /api/errors/b409cda5ade8b2ad. Report an issue: GitHub.