円弧のNSBezierPath

- (void) appendBezierPathWithArcWithCenter:radius:startAngle:endAngle:でいいじゃんとか言わない．

    double CX= __CENTER_X_; 
    double CY= __CENTER_X_; 
    double r= __RADIUS__
    double b= __RATIO__0_TO_1_;

    NSBezierPath *path= [NSBezierPath bezierPath];    
    double a= 4.0/3.0 * (sqrt(2)-1) * r;
    double c= 0.0;
    [path moveToPoint:NSMakePoint(+r, 0)];
    if (b>0.25) {
     [path curveToPoint:NSMakePoint(0, +r) 
       controlPoint1:NSMakePoint(+r, +a) 
       controlPoint2:NSMakePoint(+a, +r)];
     b-= 0.25;
     c+= 90.0;
    }
    if (b>0.25) {
     [path curveToPoint:NSMakePoint(-r, 0) 
       controlPoint1:NSMakePoint(-a, +r) 
       controlPoint2:NSMakePoint(-r, +a)];
     b-= 0.25;
     c+= 90.0;
    }
    if (b>0.25) {
     [path curveToPoint:NSMakePoint(0, -r) 
       controlPoint1:NSMakePoint(-r, -a) 
       controlPoint2:NSMakePoint(-a, -r)];
     b-= 0.25;
     c+= 90.0;
    }
    if(b==0.25) {
     [path curveToPoint:NSMakePoint(+r, 0)
       controlPoint1:NSMakePoint(+a, -r) 
       controlPoint2:NSMakePoint(+r, -a)];    
     //b-= 0.25;
     //c+= 90.0;
    }
    else if (b<0.25) {
     NSAffineTransform *affine= [NSAffineTransform transform];
     [affine rotateByDegrees:c];
     double t= b/0.25;
     double it= (1.-t);
     [path curveToPoint:[affine transformPoint:NSMakePoint(+cos(t*M_PI_2)*r, +sin(t*M_PI_2)*r)] 
       controlPoint1:[affine transformPoint:NSMakePoint(+r, +a*t)] 
       controlPoint2:[affine transformPoint:NSMakePoint(+(it*it*r+2*it*t*r+t*t*a), +(it*it*0+2*it*t*a+t*t*r))]
      ];
    }
    NSAffineTransform *affine= [NSAffineTransform transform];
    [affine translateXBy:CX yBy:CY];
    //[affine rotateByDegrees:45];
    [path transformUsingAffineTransform:affine];

開始点を変更したい場合は最後の平行移動前(書く時は後ろ)にて回転させればよい．(コメント部)
描画ならCGContextAddArcか．

参考: s.h's page - [graphic] ベジエ曲線