module util;

#define FRAC_1_SQRT_2 0.7071067811865475244008443621048490392848359376884740365883398689

public float2 cmul(float2 x, float2 y) {
  return float2(x[0] * y[0] - x[1] * y[1], x[0] * y[1] + x[1] * y[0]);
}

public float2 mul_ni(float2 x) {
    return float2(x[1], -x[0]);
}

public float2 rot_45(float2 c) {
    return float2(c[0] - c[1], c[0] + c[1]) * FRAC_1_SQRT_2;
}

public float2 rot_90(float2 c) {
    // The standard 2D rotation matrix gives:
    //  [ cos(pi/2) -sin(pi/2)]   [ 0 -1 ]
    //  [ sin(pi/2)  cos(pi/2)] = [ 1  0 ]
    return float2(-c[1], c[0]);
}

public float2 rot_180(float2 c) {
    // The standard 2D rotation matrix gives:
    //  [ cos(pi) -sin(pi)]   [ -1  0 ]
    //  [ sin(pi)  cos(pi)] = [  0 -1 ]
    return float2(-c[0], -c[1]);
}

public float2 rot_270(float2 c) {
    // The standard 2D rotation matrix gives:
    //  [ cos(3pi/2) -sin(3pi/2)]   [  0 1 ]
    //  [ sin(3pi/2)  cos(3pi/2)] = [ -1 0 ]
    return float2(c[1], -c[0]);
}