docs: build_flags.md

README.md

@@ -65,6 +65,7 @@ so other languages you should use the libraries written specifily for thoses lan
 
 - Why Unlicense? Mostly source codes were re-written from The-Forge's VectorMath library, so I don't own the code. (I found the code with the same design with this library, but older: https://github.com/zauonlok/renderer/blob/master/renderer/core/maths.h)
 - Where the functions docs, and tutorials? WIP.
+- Advance usages, configs, build flags docs? Find out in [build_flags](docs/build_flags.md).
 - More examples on some popular renderers (bgfx, The-Forge)? Learning.
 - I want to use it with Raylib? replace struct definition of VectorX with typedef and it will work, Matrix must be do more work.
 - More about performance? Not the fastest, but enough to use with small project.

docs/build_flags.md

@@ -0,0 +1,14 @@
+# Build flags and config details
+- `VECTORMATH_ENABLE_CLANG_EXT`:
+    - Compiler options: `-DVECTORMATH_ENABLE_CLANG_EXT`
+    - Use clang vector extensions, only work with clang compiler.
+    - Clang vector extensions support swizzle syntaxes.
+
+- `VECTORMATH_SIMD_ENABLE`:
+    - Compiler options: `-DVECTORMATH_SIMD_ENABLE`
+    - Prefer to use SIMD if available, autoconfig to use SSE or NEON based on target platform.
+
+- `VECTORMATH_USE_EXACT_PRECISION`:
+    - Compiler options: `-DVECTORMATH_USE_EXACT_PRECISION`
+    - Prefer good precision over fast math (currently use idSoftware FastInvSqrt)
+    - Planning to do some fast trigonometric with simd instructions