1.pscale 统一规格化的属性,浮点
2.bbox表达式写法bbox(<surface_node>, <type>)
3.vector min;
vector max;
getbbox(0,min,max);
float ramp=fit(@P.x,min.x,max.x,0,1);
//@Cd=set(ramp,0,0);
float width=chf("width");
if(ramp>width && ramp<1-width){
removepoint(0,@ptnum);
}
&& mean and || mean or