%------------------------------------------------------------------------
%                       SWARM SIMULATION PROGRAM 
%                        DESIGNED BY Jun Lu
%                   Intelligent and Complex Systems Lab
%               HuaZhong University of Science and Technology
%------------------------------------------------------------------------

%判斷垂點是在起點和終點的連線上，還是在連線的延長線上
function sign = check_on_line(line_x1, line_y1, line_x2, line_y2, point_x, point_y)  %起點，終點，垂點

if(line_x1 == line_x2)
    if(line_y2<line_y1)
       if((point_y<line_y2)|(point_y>line_y1))
          sign = 0;
          return;
       end
    else
       if((point_y>line_y2)|(point_y<line_y1))
          sign = 0;
          return;
        end
    end
else
    if(line_x2<line_x1)
       if((point_x<line_x2)|(point_x>line_x1))
          sign = 0;
          return;
       end
    else %line_x2>line_x1
       if((point_x>line_x2)|(point_x<line_x1))
          sign = 0;
          return;
       end
    end
end

if(line_y1 == line_y2)
    if(line_x2<line_x1)
       if((point_x<line_x2)|(point_x>line_x1))
         sign = 0;
         return;
       end
    else
       if((point_x>line_x2)|(point_x<line_x1))
          sign = 0;
          return;
        end
    end
else
    if(line_y2<line_y1)
       if((point_y<line_y2)|(point_y>line_y1))
          sign = 0;
          return;
       end
    else %line_y2>line_y1
       if((point_y>line_y2)|(point_y<line_y1))
          sign = 0;
          return;
       end
    end
end

sign = 1;