FlyView: display Catmull-Rom curve for spline waypoints

[leonfliesthings-dev]

Summary

QGC draws straight lines between NAV_SPLINE_WAYPOINT (cmd 82) mission items, even though ArduPilot flies smooth Hermite/Catmull-Rom curves through them. This makes it difficult for operators to visualize the actual flight path when using spline waypoints.

This PR adds a cyan Catmull-Rom interpolation overlay on the fly map that shows the approximate spline curve between consecutive spline waypoints.

How it works

• A MapPolyline in FlyViewMap.qml polls the mission controller's visualItems every 3 seconds
• When spline waypoints (cmd 82) are detected, it computes Catmull-Rom interpolation between consecutive waypoints
• The curve is drawn as a cyan overlay on the map (3px wide, 85% opacity)
• Only renders when spline waypoints are present — no effect on regular waypoint missions
• Minimal performance impact: computation only runs when the mission item count changes

Screenshots

The cyan line shows the approximate spline curve ArduPilot will fly, overlaid on the straight-line mission path display.

Testing

• Loaded mission with NAV_SPLINE_WAYPOINT items in SITL
• Cyan curve appears on the fly map showing smooth paths between waypoints
• No curve shown for missions using only NAV_WAYPOINT (cmd 16)
• No performance impact observed

[github-actions]

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A maintainer will review this soon. Please ensure:

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• Code follows coding standards
• Changes tested on relevant platforms

We appreciate your contribution to QGroundControl!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 26.47%. Comparing base (f29efd3) to head (0946f8b).
⚠️ Report is 32 commits behind head on master.

❌ Your project check has failed because the head coverage (26.47%) is below the target coverage (30.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14433      +/-   ##
==========================================
+ Coverage   25.47%   26.47%   +1.00%     
==========================================
  Files         769      767       -2     
  Lines       65912    66285     +373     
  Branches    30495    30667     +172     
==========================================
+ Hits        16788    17546     +758     
+ Misses      37285    36280    -1005     
- Partials    11839    12459     +620     

Flag	Coverage Δ
unittests	26.47% <ø> (+1.00%)	⬆️

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see 133 files with indirect coverage changes

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[github-actions]

Build Results

Platform Status

Platform	Status	Details
Linux	Passed	View
Windows	Passed	View
MacOS	Passed	View
Android	Passed	View

All builds passed.

Pre-commit

Check	Status	Details
pre-commit	Failed (non-blocking)	View

Pre-commit hooks: 2 passed, 42 failed, 7 skipped.

Test Results

linux-coverage: 88 passed, 0 skipped
Total: 88 passed, 0 skipped

Code Coverage

Coverage	Baseline	Change
60.4%	60.4%	+0.0%

Artifact Sizes

Artifact	Size	Δ from master
QGroundControl	216.77 MB	-4.61 MB (decrease)
QGroundControl-aarch64	176.66 MB	-0.01 MB (decrease)
QGroundControl-installer-AMD64	134.68 MB	-0.00 MB (decrease)
QGroundControl-installer-AMD64-ARM64	77.48 MB	-0.01 MB (decrease)
QGroundControl-installer-ARM64	106.03 MB	+0.00 MB (increase)
QGroundControl-linux	186.86 MB	-147.82 MB (decrease)
QGroundControl-mac	186.86 MB	No change
QGroundControl-windows	186.87 MB	No change
QGroundControl-x86_64	172.32 MB	+0.01 MB (increase)
Total size decreased by 152.44 MB

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_{Updated: 2026-05-24 08:59:15 UTC • Triggered by: Linux}