Find area of Triangle(A) and area of Polygon with these four points(B) if A<B point lies outside triangle if A>B point lies inside triangle else on if they are equal, it lies on triangle.
On Mon, Sep 20, 2010 at 10:39 PM, Nikhil Agarwal <nikhil.bhoja...@gmail.com>wrote: > > Method 1: > Yes you can do by writing equation of 3 lines taking 2 points at a time > and finding the sign with the third point. > > Suppose: ax+by+c=0 is your first line and (x,y) is the third point then > find out the sign of the 3rd point satisfying it on the line. suppose this > sign is S (for +ve) > > Similarly calculate for signs for other 2 lines. > > Now give a point(p,q) should give the same signs for all the 3 lines .If it > gives the same sign for all the 3 lines that means it lies btwn all the 3 > lines and all the 3 points.hence proved. > > Method 2: Area mentioned by praveen > > Method 3: > http://en.wikipedia.org/wiki/Barycentric_coordinates_(mathematics)#Determining_if_a_point_is_inside_a_triangle > > You can choose the best method. > > On Mon, Sep 20, 2010 at 9:18 PM, Nicolae Titus > <nicolaetitu...@gmail.com>wrote: > >> there are some approximations involved there, it should be (area(big) - >> sum(area small)) < error >> a better approach would be to find if the point is on the proper side of >> each edge >> take all the edges clockwise and calculate the sinus between each edge and >> the point, if they are all positive, the point is inside. >> >> Titus >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Algorithm Geeks" group. >> To post to this group, send email to algoge...@googlegroups.com. >> To unsubscribe from this group, send email to >> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> >> . >> For more options, visit this group at >> http://groups.google.com/group/algogeeks?hl=en. >> > > > > -- > Thanks & Regards > Nikhil Agarwal > Senior Undergraduate > Computer Science & Engineering, > National Institute Of Technology, Durgapur,India > http://tech-nikk.blogspot.com > http://beta.freshersworld.com/communities/nitd > > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algoge...@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > -- <<Bharath>> -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
