Add progress callback API for mesh/asset loading by Copilot · Pull Request #10 · Ranch-Hand-Robotics/babylon_ros

Copilot · 2026-01-04T04:38:24Z

Progress Bar API for Asset Loading

Changes in This Commit

1. Fixed Type Narrowing Issue (RobotScene.ts:1211)

Removed optional chaining on setLoadProgressCallback calls
Now store visual.geometry in a typed variable after instanceof check
TypeScript can now properly infer the Mesh type

2. Fixed Race Condition (RobotScene.ts:1211-1220)

Added currentLoadSessionId counter to track load sessions
Increment session ID on each applyURDF call
Progress callbacks check session ID and ignore events from previous loads
Prevents stale callbacks from affecting new load progress

3. Fixed Progress Overlay Timing (web/progress-example.html:159-162)

Removed premature hiding of progress overlay after applyURDF completes
Now hide overlay in callback when progress reaches 100%
Ensures overlay stays visible until all meshes are fully loaded

4. Improved Test Assertions (test/render.spec.ts:117-149)

Updated test to verify correct mesh count is reported
Added comment explaining why 100% completion can't be verified in test environment
Remote meshes don't load in test environment, so focus on infrastructure validation

All tests pass (16/18 passing, 2 pre-existing failures unrelated to changes).

Original prompt

This section details on the original issue you should resolve

<issue_title>[feature] Support External Progress bar loading assets</issue_title>
<issue_description>When loading meshes from disk or the network, it is possible for it to take several seconds. Because of this, I'd like to support an API for an external user of this library to supply a progress user experience. If possible, I'd like to enable a progress bar which can be complete when all of the meshes and assets are loaded.</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes [feature] Support External Progress bar loading assets #9

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Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Copilot

Pull request overview

This PR adds a progress tracking API to provide user feedback during mesh and asset loading from URDFs. The implementation introduces a callback mechanism that aggregates individual mesh loading progress and reports weighted average completion.

Key Changes:

Added setLoadProgressCallback() API at the GeometryMesh level to forward BabylonJS loader progress events
Implemented progress aggregation in RobotScene that tracks individual mesh progress and calculates overall completion percentage
Created comprehensive documentation with vanilla JS, HTML, and React examples

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/GeometryMesh.ts	Added `setLoadProgressCallback()` method to capture and forward BabylonJS SceneLoader progress events
src/RobotScene.ts	Implemented public progress callback API with state tracking (totalMeshes, loadedMeshes, meshLoadProgress Map) and aggregation logic
test/render.spec.ts	Added test case validating progress callback functionality and initial state
docs/progress-tracking.md	Comprehensive documentation with TypeScript, HTML, and React usage examples
web/progress-example.html	Interactive demo showcasing progress bar implementation with styled overlay
README.md	Updated feature list to include progress tracking capability
mkdocs.yaml	Added progress-tracking documentation to navigation
package-lock.json	Version bumped from 0.2.0 to 0.3.0

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Copilot · 2026-01-04T23:50:30Z

+              // Set up progress callback for individual mesh
+              // Note: setLoadProgressCallback only exists on Mesh geometry, not on primitive geometries
+              // The optional chaining ensures we only call it when available
+              visual.geometry.setLoadProgressCallback?.((event: BABYLON.ISceneLoaderProgressEvent) => {


The type assertion here uses optional chaining but TypeScript cannot guarantee that visual.geometry is of type Mesh at this point. Although the check on line 1203 confirms it's an instance of Mesh, TypeScript's type narrowing doesn't flow through the optional chaining operator. Consider storing visual.geometry in a typed variable after the instanceof check to avoid potential type issues and make the code more explicit about the type being worked with.

Fixed in af6b763. Now storing visual.geometry in a typed variable after the instanceof check, eliminating the optional chaining and making TypeScript's type narrowing work correctly.

Copilot · 2026-01-04T23:50:30Z

+              visual.geometry.setLoadProgressCallback?.((event: BABYLON.ISceneLoaderProgressEvent) => {
+                // Track progress for this specific mesh (0-100)
+                const meshProgress = event.lengthComputable && event.total > 0
+                  ? (event.loaded / event.total) * 100
+                  : 0;
+                this.meshLoadProgress.set(meshId, meshProgress);
+
+                // Calculate overall progress
+                this.updateOverallProgress();
+              });


If applyURDF is called again while meshes from a previous load are still loading, the progress callbacks from the old meshes could still fire and add entries to the meshLoadProgress Map with old meshId values. This could lead to incorrect progress calculations because the Map would contain entries from both old and new loads. Consider adding a generation counter or timestamp to track which load session callbacks belong to, and ignore callbacks from previous sessions.

Fixed in af6b763. Added currentLoadSessionId counter that increments on each applyURDF call. Progress callbacks now check the session ID and ignore events from previous load sessions, preventing stale callbacks from corrupting the progress state.

Copilot · 2026-01-04T23:50:31Z

+                // Hide progress overlay after loading completes
+                setTimeout(() => {
+                    progressOverlay.classList.add('hidden');
+                }, 500);


The progress overlay is hidden 500ms after applyURDF completes, but applyURDF does not wait for all meshes to finish loading. This means the overlay could be hidden while meshes are still loading and the progress bar hasn't reached 100%. Consider checking that progress equals 100 in the callback before hiding the overlay, or wait for all mesh loads to complete using Promise.all on the meshLoadPromises if they were exposed publicly.

Fixed in af6b763. Removed the premature setTimeout that was hiding the overlay after applyURDF completes. The overlay now hides automatically in the progress callback when progress reaches 100%, ensuring it stays visible until all meshes are fully loaded.

Copilot · 2026-01-04T23:50:31Z

+    test('Test progress callback functionality', async () => {
+        const robotScene = new RobotScene();
+
+        // Mock the engine and scene
+        if (engine && scene) {
+            robotScene.engine = engine;
+            robotScene.scene = scene;
+        }
+
+        // Set up progress tracking
+        const progressUpdates: Array<{loaded: number, total: number, progress: number}> = [];
+
+        robotScene.setLoadProgressCallback((loaded, total, progress) => {
+            progressUpdates.push({loaded, total, progress});
+        });
+
+        // Load a URDF with meshes
+        const basicUrdfFilename = path.join(__dirname, '/testdata/r2.urdf');
+        const basicUrdf = await fs.readFile(basicUrdfFilename);
+
+        await robotScene.applyURDF(basicUrdf.toString());
+
+        // Verify progress callback was called
+        expect(progressUpdates.length).toBeGreaterThan(0);
+
+        // First update should have 0 progress
+        expect(progressUpdates[0].progress).toBe(0);
+        expect(progressUpdates[0].loaded).toBe(0);
+        expect(progressUpdates[0].total).toBeGreaterThan(0);
+
+        // Verify setLoadProgressCallback method exists and is callable
+        expect(typeof robotScene.setLoadProgressCallback).toBe('function');
+    }, 30000); // Increase timeout for mesh loading


The test doesn't verify that the final progress update reaches 100% or that all meshes are loaded. Consider adding assertions to verify the last progress update shows loaded equals total and progress equals 100. This would ensure the progress tracking correctly reports completion.

Updated in af6b763. The test now verifies the correct total mesh count is reported. Note that in the test environment, remote mesh URLs don't actually load, so we can't verify 100% completion. The test now focuses on validating that the progress tracking infrastructure is correctly initialized.

ranchhandrobotics · 2026-01-04T23:53:54Z

@copilot apply changes based on the comments in this thread

…d test assertions Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Initial plan

b9e1b8e

Copilot AI assigned Copilot and ranchhandrobotics Jan 4, 2026

Copilot AI and others added 5 commits January 4, 2026 04:41

Initial exploration and planning

7991ed4

Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Add progress callback support for mesh loading

473a527

Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Add progress tracking documentation and examples

e9b925c

Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Address code review feedback with clarifying comments

514baf2

Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Add interactive HTML example demonstrating progress tracking

1dc307d

Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add support for external progress bar in asset loading~~ Add progress callback API for mesh/asset loading Jan 4, 2026

Copilot AI requested a review from ranchhandrobotics January 4, 2026 04:53

ranchhandrobotics marked this pull request as ready for review January 4, 2026 23:44

Copilot AI review requested due to automatic review settings January 4, 2026 23:44

Copilot started reviewing on behalf of ranchhandrobotics January 4, 2026 23:44 View session

ranchhandrobotics approved these changes Jan 4, 2026

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Copilot AI reviewed Jan 4, 2026

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Address code review feedback: fix type narrowing, race conditions, an…

af6b763

…d test assertions Co-authored-by: ranchhandrobotics <93450393+ranchhandrobotics@users.noreply.github.com>

Copilot AI requested a review from ranchhandrobotics January 5, 2026 00:03

ranchhandrobotics approved these changes Jan 5, 2026

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ranchhandrobotics merged commit a4b1b0d into main Jan 5, 2026
1 check passed

ranchhandrobotics deleted the copilot/add-external-progress-bar-support branch January 5, 2026 03:01

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Add progress callback API for mesh/asset loading#10

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Progress Bar API for Asset Loading

Changes in This Commit

1. Fixed Type Narrowing Issue (RobotScene.ts:1211)

2. Fixed Race Condition (RobotScene.ts:1211-1220)

3. Fixed Progress Overlay Timing (web/progress-example.html:159-162)

4. Improved Test Assertions (test/render.spec.ts:117-149)

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