egametang/ET · error · Exception

0 vertex index

Error message

0 vertex index

What it means

Thrown by ObjImporter.GetIndex when a face vertex reference resolves to index 0. OBJ indices are 1-based positive or negative (relative to end); 0 is explicitly invalid. This happens when a face references '0' or a component ('0/0/0') that decodes to zero.

Source

Thrown at Packages/cn.etetet.recast/Scripts/Core/Share/Recast/ObjImporter.cs:134

        private static int ReadFaceVertex(string face, ObjImporterContext context)
        {
            string[] v = face.Split("/");
            return GetIndex(int.Parse(v[0]), context.vertexPositions.Count);
        }

        private static int GetIndex(int posi, int size)
        {
            if (posi > 0)
            {
                posi--;
            }
            else if (posi < 0)
            {
                posi = size + posi;
            }
            else
            {
                throw new Exception("0 vertex index");
            }

            return posi;
        }
    }
}

View on GitHub (pinned to 5cab01f7a8)

Solutions

1. Locate the 'f' line referencing 0 and correct it to a valid 1-based (or valid negative) index.
2. Re-export from the source tool with correct OBJ 1-based indexing.
3. Pre-scan face tokens and reject any that equal 0 before importing.

Example fix

// before
f 0 1 2

// after
f 1 2 3

foreach (var line in lines)
    if (line.StartsWith("f "))
        foreach (var tok in line.Substring(2).Split(' ', StringSplitOptions.RemoveEmptyEntries))
        {
            int slash = tok.IndexOf('/');
            int pos = int.Parse(slash < 0 ? tok : tok.Substring(0, slash));
            if (pos == 0) throw new InvalidDataException($"Zero OBJ index in: {line}");
        }

static bool HasNoZeroIndex(string faceToken)
{ var p = faceToken.Split('/')[0]; return int.TryParse(p, out int i) && i != 0; }

try { ObjImporter.Load(chunk); }
catch (Exception e) when (e.Message.Contains("0 vertex index"))
{ /* correct the offending face reference */ }

When it happens

Trigger: An 'f' line containing a literal 0 vertex reference (e.g., 'f 0 1 2'); a face vertex like '0/1/1' whose position index is 0.

Common situations: Exporters that zero-index instead of 1-indexing; hand-authored faces with a typo'd 0; corrupted face data.

Related errors

• Invalid vector, expected 3 coordinates, found {v.Length - 1}
• Invalid number of face vertices: 3 coordinates expected, fou
• {e.Message}
• 如果项非string类型，则必需设置解析器
• condition number parse error: {text}

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/cf3893226855da6d. Report an issue: GitHub.