culling stuff camera

 string camera=chs("../camera");

vector campos=toNDC(camera,@P);

vector2 padding =chu("../padding");

if((campos.x+padding.x)<0||(campos.x-padding.x)>1||(campos.y+padding.y)||(campos.y-padding.y)){

        i@group_kill=1;}

matrix cam=optransform(camera);

vector camera_position=cracktransform(0,0,0,{0,0,0}, cam);

float distance =distance (camera_position,@P);

float threshold=chf("../distance");

if(distance>threshold){

        i@group_kill=1;}