FyroxEngine/Fyrox · error

: Mesh has a triangle with a zero-length edge!

Error message

{}: Mesh has a triangle with a zero-length edge!

What it means

During glTF mesh import, Fyrox computes the minimum edge length across all triangles and logs this error when an edge has exactly zero length, i.e. a triangle has two identical vertices. Such degenerate triangles produce invalid normals and broken rendering, so the importer flags the source asset as defective.

Solutions

1. Open the model in a DCC tool and remove degenerate faces (e.g. Blender: Select All, Mesh > Clean Up > Degenerate Dissolve).
2. Run a mesh-cleanup pass in the export pipeline (merge by distance, remove zero-area faces) and re-export the glTF.
3. If the asset cannot be fixed, use a mesh processing tool (meshoptimizer, Blender's 3D-Print toolbox) to strip degenerate triangles before import.

Example fix

// before: exporting mesh with duplicated vertices
gltf_primitive indices [0,1,1] // zero-length edge

// after: dissolve degenerate triangles before export
# Blender: Edit Mode > Select All > Mesh > Clean Up > Degenerate Dissolve

// Before loading, validate mesh triangles in the glTF JSON/asset:
// ensure no primitive triangle reuses a vertex index within a triangle
// and no two triangle vertices coincide positionally.
fn has_degenerate_edges(positions: &[[f32; 3]], indices: &[u32]) -> bool {
    indices.chunks(3).any(|t| {
        let (a, b, c) = (positions[t[0] as usize], positions[t[1] as usize], positions[t[2] as usize]);
        a == b || b == c || a == c
    })
}

When it happens

Trigger: Loading a glTF/GLB file via ResourceManager (import_meshes during import_from_slice) where any triangle in a mesh primitive has two vertices at identical positions (min_edge_length() == 0.0).

Common situations: Exporting models from DCC tools (Blender, 3ds Max) with unmerged duplicate vertices, decimated meshes collapsed to zero-area triangles, or procedural geometry generators emitting duplicate vertex indices.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• : Model has triangles with repeated vertices
• : Mesh has a triangle with edge length
• Failed to import animation
• glTF material failed to import. Reason
• A node with existing name

AI-assisted analysis of FyroxEngine/Fyrox@76c91aad8e (2026-09-10). Data as JSON: /api/errors/ea3f15fcf35a24ea. Report an issue: GitHub.

Appendix: source

Thrown at fyrox-impl/src/resource/gltf/mod.rs:472

) -> Result<Vec<MeshData>> {
    let mut result: Vec<MeshData> = Vec::with_capacity(gltf.nodes().len());
    let mut stats = GeometryStatistics::default();
    for node in gltf.nodes() {
        if let Some(mesh) = node.mesh() {
            result.push(import_mesh(mesh, mats, bufs, &mut stats)?);
        }
    }
    if cfg!(feature = "mesh_analysis") {
        if stats.repeated_index_count > 0 {
            Log::err(format!(
                "{}: Model has triangles with repeated vertices: {}",
                path.to_string_lossy(),
                stats.repeated_index_count
            ));
        }
        let min_length = stats.min_edge_length();
        if min_length == 0.0 {
            Log::err(format!(
                "{}: Mesh has a triangle with a zero-length edge!",
                path.to_string_lossy()
            ));
        } else if min_length <= f32::EPSILON {
            Log::err(format!(
                "{}: Mesh has a triangle with edge length: {}",
                path.to_string_lossy(),
                min_length
            ));
        } else {
            Log::info(format!(
                "{}: Smallest triangle edge: {}",
                path.to_string_lossy(),
                min_length
            ));
        }
    }
    Ok(result)

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