mathlib.c

#include "mathlib.h"

#define RAD_2_DEG (180.0 / PI)
#define DEG_2_RAD (PI / 180.0)

double lerp(double a, double b, double t) {
  return (1.0-t)*a + t*b;
}

double sign(double a) {
  return a >= 0 ? 1.0 : -1.0;
}

Vec2 rotate(Vec2 v, double a) {
  a *= DEG_2_RAD;
  return (Vec2){
    .x = v.x*cos(a) - v.y*sin(a),
    .y = v.y*cos(a) + v.x*sin(a)
  };
}

double magnitude(Vec2 v) {
  return sqrt(v.x*v.x + v.y*v.y);
}

double sqr_magnitude(Vec2 v) {
  return v.x*v.x + v.y*v.y;
}

Vec2 normalize(Vec2 v) {
  double mag = magnitude(v);
  return (Vec2){
    .x = v.x / mag,
    .y = v.y / mag
  };
}

Vec2 invert(Vec2 v) {
  return (Vec2){
    .x = -v.x,
    .y = -v.y
  };
}