A small 3D rigid body physics engine.

Copy picophysics.h into your project. In exactly one .c file:

#define PICOPHYSICS_IMPLEMENTATION
#include "picophysics.h"

Everywhere else, just include it. Then:

PPVec3 g = {.xyz = {0, -9.8f, 0}}, p = {.xyz = {0, 5, 0}};
pp_physics_set_gravity(&g);
PPBody *ball = pp_physics_create_sphere(0.5f, &p, 1.0f, 0);

pp_physics_step(1.0f / 60.0f, 8, 4);   // once per frame

Pools are small by default (32 bodies, 128 triangles). Raise them by defining PICOPHYSICS_MAX_OBJECTS, PICOPHYSICS_MAX_TRIANGLES and friends before the implementation include. The API is documented in the header.

Define PICOPHYSICS_USE_SH4ZAM

git submodule update --init      # pulls SH4ZAM into extern/, for tests_sh4zam
mkdir build && cd build
cmake ..
make
./tests/tests
./tests/tests_sh4zam             # same tests, maths through SH4ZAM

NOTE: For KOS users, use kos-cmake instead of cmake. Both suites then come out as Dreamcast ELFs, and make run-tests / make run-tests-sh4zam

On a PC tests_sh4zam uses SH4ZAM's software back-end, so SH4ZAM quirks show up as a failing test rather than as boxes falling through the floor on hardware. It cannot reproduce the SH4's own arithmetic (reduced-precision 1/sqrt, table-driven sin/cos), so run the Dreamcast build too.

MIT or public domain, your choice. See the end of picophysics.h.