Incorrect NavigationPolygon.add_outline() calculation

[spikeyarmaku]

Godot version

v4.1.1.stable.official [bd6af8e]

System information

Godot v4.1.1.stable - Windows 10.0.19045 - Vulkan (Mobile) - dedicated Radeon RX Vega (Advanced Micro Devices, Inc.; 31.0.12027.9001) - AMD Ryzen 5 3600 6-Core Processor (12 Threads)

Issue description

NavigationPolygon.add_outline() produces incorrect result with specific values. However, if I nudge the first point by a tiny amount (the uncommented line in the gif), it works correctly.

Steps to reproduce

• Open the supplied project
• Select Debug -> Visible Navigation
• Either comment or uncomment the first line in _ready()
• Run the project

If the first line in _ready() is commented out (which nudges the first point on the X axis), the issue crops up. If it is uncommented, the issue goes away. Nudging any other point doesn't have an effect on the result.

Minimal reproduction project

polygon2d bug.zip

[smix8]

Closing as a duplicate of #70823.