Continuous Visible Query for Three-Dimensional Objects in Spatial Databases

Algorithm 2

Continuous visible range query based on control point.

Input: QueryArea ; ObjectSet ; Range ;

Output: ResultSet

(1) (); //do the range query,

(2) Sorting();

(3) for  (every element in )  do

(4)  for  (every element in )  do

(5)   getVisibleArea;

(6)   if  Boolean( parallel )  then

(7)   else

(8)    getControlPoint and update VisibleArea;

(9)   end if

(10)  end for

(11)  if   is visible  then

(12)   add to and ;

(13)  end if

(14) end for

(15) ();

(15) Return ;