I was hired by @bvisness to work on the list of changes for HMM2.0. The tracking issue for all of the changes is: #147.

Changes

Here are the changes I made:

• Renaming. Types and functions have been renamed as described in the 2.0 issue: HMM 2.0 Design #147. This affects almost every file in the project.
• Angles. A consistent unit is used for angles both as inputs to functions and internally. The default is radians for both, but can be changed. To change the input unit to all HMM functions, define one of HMM_USE_DEGREE_INPUT or HMM_USE_TURN_INPUT. There are macros, HMM_AngleRad, HMM_AngleDeg, and HMM_AngleTurn that will convert an angle to the input representation, such as passing an FOV in degrees: HMM_Perspective_RH(HMM_AngleDeg(120), ... other args ...). There are also functions to convert angles in the input representation to any of the other units, HMM_ToRad, HMM_ToDeg, HMM_ToTurn.
• Configuration. Added HMM_PROVIDE_MATH_FUNCTIONS, removed individual checks for each math function being defined. Users now define this and all of the HMM_SINF and other trig functions, or accept the default crt implementations. The atanf and atan2f functions were unused and have been removed. If users override the functions, they can also use a different unit for the angles in their functions by defining both of HMM_ANGLE_USER_TO_INTERNAL and HMM_ANGLE_INTERNAL_TO_USER.
• HMM_PREFIX macro has been removed. Everything now uses an uppercase HMM_ prefix, so it should be easy to find+replace on your local copy.
• Handedness. All functions that depended on the handedness of the coordinate system have both a left and right handed version, marked by a "_LH" or "_RH" suffix respectively.
• 2x2 and 3x3 Matrices. Basic operations (Add, Sub, Mul, Div, Transpose) are implemented for each size.
• Matrix Inverses. There are determinants and general inverses for each size of matrix. For 4x4 matrices there are inverses specific to each type of matrix we have a constructor for (Orthographic, Perspective, Rotation, etc). New tests were added for the inverses.
• Overloads and _Generic. There are overloads for the new matrix sizes and the determinant and inverse functions. There is also a C11 _Generic macro for each function that was overloaded before.
• FastNorm is default. The FastNorm functions are now just the Norm functions. Precision has declined in several places from this, but is still on par with the accuracy of GLM. Per: Vector normalization could easily be faster #87
• SLerp. The Slerp implementation was not robust in cases when the quaternions were very close. It has also been changed to always take the shortest path between angles. Divide by zero when calling HMM_Slerp with two identity quaternions #135
• HMM_LinearCombineSSE is now HMM_LinearCombineV4M4. It will use the SSE code when available but fallback to a slower implementation. This reduces the amount of special cases needed for various Mat4 functions, which previously used HMM_LinearCombineSSE when available and then each had their own implementation.

Update Tool

I also created a tool that can be used to update user's code to 2.0 automatically, which you can find in a separate repository here: https://github.com/dev-dwarf/HMM2.0UpdateTool. The tool I created does the following:

• Renames types and functions to use the new naming conventions from: Make naming more consistent and concise #146
• It wraps arguments that were previously taken in degrees to convert them to radians, per: Make everything use radians #107
• Adds the "_RH" suffix to functions that depend on handedness, since now both left-handed and right handed functions are available: Make coordinate system more clear in function naming (LH, RH, NO, ZO) #75
• Removes ambiguity with matrix functions now that there are multiple sizes of matrices: mat3 #123

The tool is written in one .c file that compiles as C or C++, so any of our users should be able to compile it easily. The tool takes one or more filenames as arguments and updates their contents to 2.0. There are also .bat and .sh scripts to recursively run the tool on all the c/h/cpp/hpp files in a directory. The tool changes the files it touches so it should be used with source control. I can provide compiled executables for windows and linux, but someone else would have to handle mac.

Please take a look and let me know anything that needs changes. Sorry for the huge PR, didn't know a good way to split things up. Happy to answer any questions or make additional changes. Thanks for the opportunity!