// Shows a Bézier arc.

#include "bez.inc"
  
#macro bezarc(Q0, Q1, Q2, Q3, txs, txv)
  #local rad = 0.06;
  #local n = 200;
  union{
    sphere{ Q0, 2*rad texture{ txs } }
    sphere{ Q1, 2*rad texture{ txs } }
    sphere{ Q2, 2*rad texture{ txs } }
    sphere{ Q3, 2*rad texture{ txs } }
    #local i = 0;
    #while (i <= n)
      #local T = i/n;
      #local p = bez_pos(T, Q0, Q1, Q2, Q3);
      sphere{ p, rad texture{ txs } }
      #if ((i = 0) | (i = int(n/3)) | (i = int(2*n/3)) | (i = n))
        #local vel = bez_diff(T, Q0, Q1, Q2, Q3);
        #local dir = vnormalize(vel);
        object{ garrow(p, dir, txv) }
      #end
      #local i = i + 1;
    #end
  }
#end