Cyrus beck line clipping algorithm

Cyrus beck line clipping algorithm

• 2.
   Cohen Sutherlandline clipping algorithm work on rectangular box, but if we want to apply clipping algorithm for non- rectangular box then we use Cyrus back line clipping algorithm.  Cyrus Beck is a line clipping algorithm that is made for convex polygons.  It allows line clipping for non-rectangular windows
• 3.
   This algorithmuses one parametric equation and by using this equation we find the intersecting point of the line with the boundary of the clipping window.  Parametric equation: let us consider two line end points P0,P1, then the parametric equation will be: P(t)=P0+(P1-P0)t 0<=t<=1 if t=0 => P(t)=P0 if t=1 => P(t)=P1
• 4.
   In thisfigure P0 and P1 is a point of line.  We have to find out the only visible portion of the line and exterior potion of the line will be discarded by using this algorithm.  For example if we draw a line P0 to P1. and starting time for P0 is suppose t=0 and time of end point P1 is t=1. • In figure the initial value of P0=(-2,1) and P1=(6,3) • So this algorithm work on the find out the point which will not be discarded and what was the time of that point. P’0,p’1
• 5.
   After calculatingthe time of both point we apply both value in the below formula and calculating the point value. means this time value will help to find out the value of P’0, P’1  Here Ni, N is a normal vector and i= edge no.  Pei= point of edge  P(t) =P0+t(P1-P0) This is a Parametric Equation
• 6.
   Step 1-Firstly we find the exterior point on the edge and give a name. which is represent in a general way n(normal vector) which is an edge no.  Figure:
• 7.
   Step 2-Now take a point on every edge or a vertex which is represent by Pe1……Pei (point at edge)  Step 3- After calculating Ni or Pei then by using both value we can calculate the time for every edge of polygon. For doing things we use this formula:  Step 4- After calculating time for all edge then by using P0 and P1 and use this time below formula: and find out the value of Pe0 and P1 P(t) =P0+t(P1-P0 )