ArduBoy Mock-Steering (Seek) Algorithm

Steering.cpp

struct FPoint {
  float x; /**< The X coordinate of the point */
  float y; /**< The Y coordinate of the point */
};

FPoint steer(const FPoint& target, const FPoint& pos, const FPoint& curForward) {
  // Direction to target
  FPoint dir;
  dir.x = target.x - pos.x;
  dir.y = target.y - pos.y;
  // Normalize direction
  float mag;
  mag = sqrt(sq(dir.x) + sq(dir.y));
  dir.x = dir.x/mag;
  dir.y = dir.y/mag;
  // Steer
  return turnDirection(dir, curForward);
}

FPoint turnDirection(const FPoint& dir, const FPoint& curForward) {
  float mag;
  FPoint fwdSum; 
  // Faking it, we find the vector between curForward & dir
  fwdSum.x = dir.x + curForward.x;
  fwdSum.y = dir.y + curForward.y;
  // Normalize
  mag = sqrt(sq(fwdSum.x) + sq(fwdSum.y));
  FPoint steerVel;
  steerVel.x = fwdSum.x/mag;
  steerVel.y = fwdSum.y/mag;
  return steerVel;
}

void Example() {
  //AI Update
  // Villain AI
  if(g_villSize >= 1.0f && arduboy.everyXFrames(VILLAIN_UPDATE_DELAY)) {
    FPoint steering = steer(g_objects[PLAYER_INDX].position, g_objects[VILLAIN_INDX].position, g_objects[VILLAIN_INDX].forward);
    g_objects[VILLAIN_INDX].forward = steering;
  }
}