[Bug] ImportFile progress callback never called — progress bar stays at 0%

[JeanPhilippeKernel]

Type

• Bug

Overview

Both AssimpImporter::ImportFile() and GltfImporter::ImportFile() accept an ImportProgressCallback on_progress parameter but neither implementation calls it during processing. The importer panel's progress bar remains at 0% for the entire import duration and jumps directly to 100% on completion.

Context

AssetImporterUIComponent wires OnImportProgress as the on_progress callback, which updates m_progress (read each frame by RenderImporting()). Because the callback is never invoked, the user sees no feedback during potentially long imports (large FBX, multi-material GLB).

Relevant files:

• ZEngine/ZEngine/Importers/AssimpImporter.cpp — ImportFile() and AssimpProgressHandler::Update()
• ZEngine/ZEngine/Importers/GltfImporter.cpp — ImportFile()
• Tetragrama/Components/AssetImporterUIComponent.cpp — OnImportProgress()

AssimpImporter already has an AssimpProgressHandler class that overrides Assimp::ProgressHandler::Update(float percentage). The handler holds a pointer to the importer but does not forward the percentage to the stored on_progress callback.

What needs to be done

AssimpImporter

1. Store the on_progress callback and context pointer on AssimpProgressHandler (or on AssimpImporter as transient fields, cleared after each ImportFile call).
2. In AssimpProgressHandler::Update(float percentage), call on_progress(context, percentage) if the callback is set.

GltfImporter

1. Identify logical progress milestones in ImportFile() (e.g. after loading, after mesh extraction, after material extraction, after texture extraction, after serialization) and call on_progress(context, fraction) at each.

Testing

• Import a large FBX (> 50 MB) and verify the progress bar advances smoothly during the import.
• Import a GLB and verify the progress bar shows at least 2–3 intermediate updates before completing.

Acceptance criteria

• AssimpImporter calls on_progress via AssimpProgressHandler::Update() during assimp processing
• GltfImporter calls on_progress at each major processing stage
• Progress value is in the range [0.0, 1.0]
• Progress bar in the importer panel visibly advances during a real import
• Builds without warnings in Debug and Release
• All relevant unit tests pass
• No regression in existing functionality

Estimated effort

2–3 hours