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cmath3d

3d math library for C. Vectors, 3x3 matrices, quaternions. 32-bit floats.

motivation

This library is intended for embedded projects where C++ is not used. In the author's opinion, C++'s feature set enables dramatically more readable 3d math code. However, many embedded projects stick with C by necessity or preference. The goal of this project is to create the best possible programmer experience within the constraints of C syntax. If cmath3d is missing something you need, feature requests are encouraged.

design choices

Unlike many other C libraries of this type, cmath3d passes arguments and returns results by value instead of by pointer and pointer-to-output. This choice has several motivations:

• avoids the need to name non-meaningful intermediate results for the sake of taking their address
• enables nested expressions
• reduces bugs by allowing more variables to be declared const
• gives the optimizing compiler complete knowledge about function semantics, theoretically enabling better optimizations (see Chandler Carruth's talk)

Although Carruth's talk implies that using these functions with inline, header-only definitions -- thus hiding no code from the compiler in external object files -- will enable as good or better optimizations than a pass-by-pointer version, in practice this library seems to consume more stack memory than it should. I am currently researching ways to fix this problem, since I believe a SSA compiler with the ability to destructure structs should produce optimal code from this library.

note for users

If you use cmath3d in your project, I would very much appreciate it if you leave a comment in #2.