Function sfrand

cpp/5_Domain_Specific/smokeParticles/ParticleSystem.cpp:163–163

signed random float [-1, 1]

// signed random float [-1, 1]
inline float sfrand() { return frand() * 2.0f - 1.0f; }

// random signed vector
inline vec3f svrand() { return vec3f(sfrand(), sfrand(), sfrand()); }