{"record":{"id":"6aaea0d1b26e9b0f","repo":"bevyengine/bevy","slug":"not-enough-data-to-build-curve-needed-at-least-e","errorCode":null,"errorMessage":"Not enough data to build curve: needed at least {expected} control points but was only given {given}","messagePattern":"Not enough data to build curve: needed at least (.+?) control points but was only given (.+?)","errorType":"exception","errorClass":"InsufficientDataError","httpStatus":null,"severity":"error","filePath":"crates/bevy_math/src/cubic_splines/mod.rs","lineNumber":906,"sourceCode":"            .map(|(&a, &b)| CubicSegment {\n                coeff: [a, b - a, P::default(), P::default()],\n            })\n            .collect_vec();\n\n        if segments.is_empty() {\n            Err(InsufficientDataError {\n                expected: 2,\n                given: self.points.len(),\n            })\n        } else {\n            Ok(CubicCurve { segments })\n        }\n    }\n}\n\n/// An error indicating that a spline construction didn't have enough control points to generate a curve.\n#[derive(Clone, Debug, Error)]\n#[error(\"Not enough data to build curve: needed at least {expected} control points but was only given {given}\")]\npub struct InsufficientDataError {\n    expected: usize,\n    given: usize,\n}\n\n/// Implement this on cubic splines that can generate a cubic curve from their spline parameters.\n#[cfg(feature = \"alloc\")]\npub trait CubicGenerator<P: VectorSpace> {\n    /// An error type indicating why construction might fail.\n    type Error;\n\n    /// Build a [`CubicCurve`] by computing the interpolation coefficients for each curve segment.\n    fn to_curve(&self) -> Result<CubicCurve<P>, Self::Error>;\n}\n\n/// Implement this on cubic splines that can generate a cyclic cubic curve from their spline parameters.\n///\n/// This makes sense only when the control data can be interpreted cyclically.","sourceCodeStart":888,"sourceCodeEnd":924,"githubUrl":"https://github.com/bevyengine/bevy/blob/396ca727080776bd313bb892423b7d94e03b81b4/crates/bevy_math/src/cubic_splines/mod.rs#L888-L924","documentation":"InsufficientDataError is the error type of CubicGenerator::to_curve / CyclicCubicGenerator::to_curve_cyclic. It reports `expected` = the minimum point count for that spline and `given` = what you supplied. Point-interpolation splines (LinearSpline, CubicBezier point interpolation, Hermite) need at least 2 points; control-point splines (CubicBezierSpline with control points, CubicBSpline) need at least 4.","triggerScenarios":"Calling to_curve() (or to_curve_cyclic()) on a spline built from fewer points than its minimum: LinearSpline::new(vec![p0]).to_curve(), CubicBezierSpline::new().add_control_points([a,b,c]).to_curve() with 3 of 4, CubicBSpline with 3 points, Hermite spline with a single point.","commonSituations":"Runtime-generated trajectories that can degenerate to one point; editor tools where the user has clicked only one point; animation keyframe lists loaded from data with a missing entry; tests with tiny fixtures.","solutions":["Check the error message: `expected` tells you the exact minimum for the spline type you used; supply at least that many points.","Branch at runtime: skip curve creation or fall back to a constant/linear path when points.len() < expected.","For data-driven splines, validate keyframe counts at asset load time and reject with a descriptive asset error instead of failing mid-system."],"exampleFix":"// before\nlet spline = LinearSpline::new(vec![start]);\nlet curve = spline.to_curve()?; // InsufficientDataError { expected: 2, given: 1 }\n\n// after\nlet spline = LinearSpline::new(points.clone());\nlet curve = if points.len() >= 2 {\n    Some(spline.to_curve()?)\n} else {\n    None // or hold position / teleport to the single point\n};","handlingStrategy":"try-catch","validationCode":"const MIN_POINTS: usize = 2; // 4 for CubicBSpline / control-point CubicBezierSpline\nif spline_points.len() >= MIN_POINTS {\n    let curve = spline.to_curve()?;\n}","typeGuard":null,"tryCatchPattern":"let curve = match spline.to_curve() {\n    Ok(curve) => curve,\n    Err(InsufficientDataError { expected, given }) => {\n        warn!(\"path needs {expected} points, got {given}; holding position\");\n        return Ok(()); // skip this frame rather than crash\n    }\n};","preventionTips":["Check the docs of each spline type for its minimum point count before building it.","Validate point counts at asset/entity spawn time, not inside per-frame systems.","Keep a fallback behavior (hold position, straight line) for degenerate point lists."],"tags":["rust","bevy","math","spline","curve","runtime"],"backgroundTag":"insufficient-data-for-interpolation","analyzedSha":"396ca727080776bd313bb892423b7d94e03b81b4","analyzedAt":"2026-08-20T16:12:39.808Z","contentChangedAt":"2026-08-20T16:12:39.808Z","schemaVersion":2},"datasetVersion":"2026-09-09T06:17:21.866Z"}