缓动公式

// 角度旋转
dx = mouse.x - object.x;
dy = mouse.y - object.y;
object.rotation = Math.atan2(dy,dx)*180/Math.PI

//平滑运动
value = center + Math.sin(angle)*range;
angle += speed;

//正圆运动
x_position = centerX + Math.sin(angle)*radius;
y_position = centerY + Math.cos(angle)*radius;
angle += speed;

//椭圆运动
x_position = centerX + Math.cos(angle)*radiusX;
y_position = centerY + Math.sin(angle)*radiusY;
angle += speed;

//两点间距离
dx = x2 - x1;
dy = y2 - y1;
dist = Math.sqrt(dx*dx + dy*dy);

//任意方向速度
vx = speed * Math.cos(angle);
vy = speed * Math.sin(angle);

//任意方向加速度
ax = force * Math.cos(angle);
ay = force * Math.xin(angle);

//改变速度
vx += ax;
vx += ay;

//改变位置
object.x += vx;
object.y += vy;