allwpilib

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David Vo 44dcf9a3ca [wpilibc] Fix HSV to RGB conversion off-by-one error (#8722 )

`Color::FromHSV` didn't match the Java `Color.fromHSV` in some saturated
edge cases, introducing an off-by-one error when the HSV color should
correspond complete saturation of one or two of the primary colors.

Example:

- Java: `Color.fromHSV(0, 255, 255) -> (255, 0, 0)`
- C++: `Color::FromHSV(0, 255, 255) -> (255, 1, 1)`

This also means the following methods are also transitively affected:

- `AddressableLED::LEDData::SetHSV`
- `LEDPattern::Rainbow`

This off-by-one error is introduced by a rounding error from the chroma
calculation, which was dividing by 256 rather than the appropriate
maximum value of 255 like in Java:


7ca35e5678/wpilibj/src/main/java/edu/wpi/first/wpilibj/util/Color.java (L176-L177)

Also port appropriate tests from Java to C++ to catch this bug.

I found this bug when I tried to port `AddressableLEDBuffer` to RobotPy.
Codex found the root cause :)

2026-04-08 08:18:12 -07:00