Change Transforms.headingPitchRollToFixedFrame to use new HeadingPitchRoll

[pjcozzi]

https://github.com/AnalyticalGraphicsInc/cesium/blob/master/Source/Core/Transforms.js#L475-L481

Deprecation policy is here: https://github.com/AnalyticalGraphicsInc/cesium/tree/master/Documentation/Contributors/CodingGuide#deprecation-and-breaking-changes

@twpayne low-hanging fruit for the bug bash if you are interested.

CC #4047

[twpayne]

I'm looking at this now.

[twpayne]

AFAICT we already have aircraftHeadingPitchRollToFixedFrame which implements headingPitchRollToFixedFrame but taking a HeadingPitchRoll object instead of separate heading, pitch, and roll values.

Which of the following options would you prefer?

• Mark headingPitchRollToFixedFrame as @deprecated and replace all calls to it in the Cesium codebase with calls to aircraftHeadingPitchRollToFixedFrame as per the deprecation policy.
• Modify headingPitchRollToFixedFrame to take either a HeadingPitchRoll object or separate values (will require some arguments munging). This maintains a cleaner API but there will be a performance hit.
• Remove the original headingPitchRollToFixedFrame, rename aircraftHeadingPitchRollToFixedFrame to headingPitchRollToFixedFrame, and use HeadingPitchRoll objects throughout the codebae. This is arguably the cleanest but violates the deprecation policy.
• Something else?

[pjcozzi]

Mark headingPitchRollToFixedFrame as @deprecated and replace all calls to it in the Cesium codebase with calls to aircraftHeadingPitchRollToFixedFrame as per the deprecation policy.

The semantics of "aircraft" are a bit awkward to use internally; I would rather deprecate both of these (if the aircraft version has already shipped) and replace with a new more generically named function.

[twpayne]

As naming things is one of the two hard things in computer science, any suggestions for the new more generically named function?

• headingPitchRollToFixedFrame (the existing function name) seems to me to be the most apt, but this will require the arguments munging above to maintain backward compatibility.
• hprToFixedFrame includes a rarely-used abbreviation and so violates the naming guidelines in the coding guide.
• 🤔 ?

Note that the "aircraft" functions were made public in 4aa7eee, which was only merged into master yesterday (#4047), and so they have not yet shipped in a release.

[pjcozzi]

headingPitchRollToFixedFrame (the existing function name) seems to me to be the most apt, but this will require the arguments munging above to maintain backward compatibility

We haven't done this before, but perhaps we could just "deprecate the arguments" instead of the function. Since this is not a widely used function, I think we should give this a shot and then deprecate over 3 releases since this approach is new to us.