stride3d/stride · error · InvalidOperationException

Can't generate lightprobes if less than 4 of them exists.

Error message

Can't generate lightprobes if less than 4 of them exists.

What it means

LightProbeGenerator.GenerateRuntimeData requires at least 4 light probes because it builds a tetrahedralization (Bowyer-Watson) of probe positions, and a tetrahedron needs 4 non-coplanar points. With fewer probes, no valid tetrahedral mesh can be generated, so it throws InvalidOperationException.

Solutions

1. Add at least 4 light probes (ideally more, non-coplanar) to the volume/scene before generating runtime data.
2. Guard the generation call: only run probe baking/generation when probe count >= 4.
3. If the scene is too small for 4 probes, disable light probes or use ambient light instead of probe-based GI.
4. Fix volume/selection logic that filters probes down below the threshold unintentionally.

Example fix

// before
LightProbeGenerator.GenerateRuntimeData(probes); // throws if probes.Count < 4
// after
if (probes.Count >= 4)
    LightProbeGenerator.GenerateRuntimeData(probes);

bool canGenerateProbes(List<LightProbeComponent> probes) => probes != null && probes.Count >= 4;

try { LightProbeGenerator.GenerateRuntimeData(probes); } catch (InvalidOperationException ex) { log.Error($"Probe bake skipped: {ex.Message}"); }

When it happens

Trigger: Calling GenerateRuntimeData (directly or via light probe processing at scene build/cooking time) with a List<LightProbeComponent> containing 0-3 probes.

Common situations: A scene where only a few light probe entities were placed; probes accidentally deleted or filtered out by a volume query; automated tooling generating probes sparsely on small test scenes.

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

• A negative number of mip maps is not allowed.
• Base path must be non-empty (use null for passthrough).
• BorderColor must be float4(r, g, b, a)
• Build manifest [ ] doesn't exist
• Cannot add an asset with an empty Id

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/c0ae4af93a367926. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Engine/Rendering/LightProbes/LightProbeGenerator.cs:120

                    // Copy coefficients
                    if (lightProbe?.Coefficients != null)
                    {
                        var lightProbeCoefStart = lightProbeIndex * LambertHamonicOrder * LambertHamonicOrder;
                        for (var index = 0; index < LambertHamonicOrder * LambertHamonicOrder; index++)
                        {
                            destColors[lightProbeCoefStart + index] = index < lightProbe.Coefficients.Count ? lightProbe.Coefficients[index] : new Color3();
                        }
                    }
                }
            }
        }

        public static unsafe LightProbeRuntimeData GenerateRuntimeData(List<LightProbeComponent> lightProbes)
        {
            // TODO: Better check: coplanar, etc... (maybe the check inside BowyerWatsonTetrahedralization might be enough -- tetrahedron won't be in positive order)
            if (lightProbes.Count < 4)
                throw new InvalidOperationException("Can't generate lightprobes if less than 4 of them exists.");

            var lightProbePositions = new List<Vector3>();
            var lightProbeCoefficients = new Color3[lightProbes.Count * LambertHamonicOrder * LambertHamonicOrder];
            var destColors = lightProbeCoefficients.AsSpan();
            #if false
            ref var destColorsOrigin = ref destColors.GetPinnableReference();
            #endif

            for (var lightProbeIndex = 0; lightProbeIndex < lightProbes.Count; lightProbeIndex++)
            {
                var lightProbe = lightProbes[lightProbeIndex];

                // Copy light position
                lightProbePositions.Add(lightProbe.Entity.Transform.WorldMatrix.TranslationVector);

                // Copy coefficients
                if (lightProbe.Coefficients != null)
                {

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