knubbel.ino

#include <math.h>

int offsetX = 514, offsetY = 504;
float minX = -270, maxX = 264;
float minY = -271, maxY = 278;

void setup() {
  Serial.begin(9600);
}

float calcAngle(float _x, float _y) {
  float x = _x / maxX, y = _y / maxY;
  float c = sqrt(pow(x, 2) + pow(y, 2));
  return (acos(x / c) + (y < 0 ? PI : 0))/(2*PI) * 360.0;
}

void loop() {
  int x = analogRead(A0) - offsetX;
  int y = analogRead(A1) - offsetY;
  Serial.println(calcAngle((float)x, (float)y), DEC);
  delay(100);
}