stride3d/stride · error · ArgumentException

Need at least 1 MeshDrawData.

Error message

Need at least 1 MeshDrawData.

What it means

MeshDraw.MergeDrawData combines multiple MeshDraw instances into one, which is meaningless for an empty list, so it throws ArgumentException ('meshDrawDatas') when Count == 0. At least one MeshDrawData is required for the merge to produce output.

Solutions

1. Check meshDrawDatas.Count > 0 before calling MergeDrawData
2. Skip the merge/GroupDrawData path for empty groups
3. Fix upstream filtering that produced an empty mesh list

Example fix

// before
var merged = MeshDraw.MergeDrawData(meshDraws, can32BitIndex);
// after
if (meshDraws.Count == 0) return null;
var merged = MeshDraw.MergeDrawData(meshDraws, can32BitIndex);

if (meshDrawDatas == null || meshDrawDatas.Count == 0) return null;
var merged = MeshDraw.MergeDrawData(meshDrawDatas, can32BitIndex);

static bool Mergeable(IList<MeshDraw> list) => list != null && list.Count > 0;

try { var merged = MeshDraw.MergeDrawData(meshDrawDatas, can32BitIndex); } catch (ArgumentException) { /* empty input list */ }

When it happens

Trigger: Passing an empty IList<MeshDraw> to MergeDrawData, typically via GroupDrawData with a group that produced no meshes.

Common situations: Mesh grouping/culling pipelines where a material or draw group ends up with zero entries due to filtering, then is merged unconditionally.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• Can only merge simple MeshDrawData.
• The queue is empty
• cannot be empty.
• RenderView is null. Please make sure you have your camera…
• Unsupported depth format

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/663bbb18c352ca6c. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Rendering/Extensions/MergeExtensions.cs:24

using System.Runtime.InteropServices;
using Stride.Core;
using Stride.Graphics;
using Stride.Graphics.Data;
using Stride.Rendering;

namespace Stride.Extensions
{
    public static class MergeExtensions
    {
        /// <summary>
        /// Transform a vertex buffer positions, normals, tangents and bitangents using the given matrix.
        /// </summary>
        /// <param name="meshDrawDatas">The mesh draw datas.</param>
        /// <param name="can32BitIndex">A flag stating if 32 bit index buffers.</param>
        public static unsafe MeshDraw MergeDrawData(IList<MeshDraw> meshDrawDatas, bool can32BitIndex)
        {
            if (meshDrawDatas.Count == 0)
                throw new ArgumentException("Need at least 1 MeshDrawData.", "meshDrawDatas");

            if (meshDrawDatas.Count == 1)
                return meshDrawDatas[0];

            // Check that vertex buffer declarations are matching
            var firstMeshDrawData = meshDrawDatas[0];
            if (!firstMeshDrawData.IsSimple())
                throw new InvalidOperationException("Can only merge simple MeshDrawData.");

            var firstVertexBuffer = firstMeshDrawData.VertexBuffers[0];
            var hasIndexBuffer = IsIndexed(meshDrawDatas);
            int totalVertexCount = 0;
            int totalIndexCount = 0;

            //TODO: extend to non-simple vertex declarations, fill with default values it missing declarations etc. ?

            for (int i = 0; i < meshDrawDatas.Count; i++)
            {

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