碎部点方位角 ${\alpha }_{AB}+\theta$

碎部点坐标增量dx、dy

$0\le {\alpha }_{AB}+\theta \le 90$ or $0\le {\alpha }_{AB}+\theta -360\le 90$

$dx=SP\ast \left|\cos \left({\alpha }_{AB}+\theta \right)\right|$

$dy=SP\ast \left|\sin \left({\alpha }_{AB}+\theta \right)\right|$

$90<{\alpha }_{AB}+\theta \le 180$ or $90<{\alpha }_{AB}+\theta -360\le 180$

$dx=-1\ast SP\ast \left|\cos \left({\alpha }_{AB}+\theta \right)\right|$

$dy=SP\ast \left|\sin \left({\alpha }_{AB}+\theta \right)\right|$

$180<{\alpha }_{AB}+\theta \le 270$ or $180<{\alpha }_{AB}+\theta -360\le 270$

$dx=-1\ast SP\ast \left|\cos \left({\alpha }_{AB}+\theta \right)\right|$

$dy=-1\ast SP\ast \left|\sin \left({\alpha }_{AB}+\theta \right)\right|$

$270<{\alpha }_{AB}+\theta \le 360$ or $270<{\alpha }_{AB}+\theta -360\le 360$

$dx=SP\ast \left|\cos \left({\alpha }_{AB}+\theta \right)\right|$

$dy=-1\ast SP\ast \left|\sin \left({\alpha }_{AB}+\theta \right)\right|$