Build failure: M_PI and M_PI_2 undeclared in tools/precalculator.c

[PinkNekoFist]

Description

I encountered a build error when running make on a Linux environment. The compilation fails because the math constants M_PI and M_PI_2 are undeclared in tools/precalculator.c.

This usually happens when compiling with strict standard flags (e.g., -std=c99 or -ansi), as these constants are POSIX extensions and not part of the strict ISO C standard.

Error Log

tools/precalculator.c: In function ‘precalculate’:
tools/precalculator.c:44:35: error: ‘M_PI_2’ undeclared (first use in this function)
   44 |         float angle = i * (float) M_PI_2 / 256.0f;
      |                                   ^~~~~~
tools/precalculator.c:56:59: error: ‘M_PI’ undeclared (first use in this function)
   56 |         float s = 256.0f * sinf(i / 1024.0f * 2 * (float) M_PI);
      |                                                           ^~~~
make: *** [Makefile:62: precalculator] Error 1

Proposed Fix

To resolve this while maintaining portability, we should define these constants if they are missing.

In tools/precalculator.c, adding the following block before the logic starts (or after the includes) resolves the issue:

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

#ifndef M_PI_2
#define M_PI_2 1.57079632679489661923
#endif

Alternatively, defining _GNU_SOURCE (for Linux) or _USE_MATH_DEFINES (for MSVC) before including <math.h> would also expose the library constants.

Environment

• OS: Linux (Ubuntu/Debian)