area of 3 triangles being formed by joining the point to 3 vertices can be float n when we add the 3 areas, the sum wud also be float. and this is to b compared with original area don't u think the problem wud arise in comparing the floats? wud that give right ans??
On Fri, Jul 29, 2011 at 9:06 PM, Don <[email protected]> wrote: > That should work, but I'd bet that my method is faster. > Don > > On Jul 29, 6:02 am, Udit Gupta <[email protected]> wrote: > > Join the given point with all the vertices of the triangle and calculate > the > > area of each of the three sub-triangles thus formed > > now compare the area of original triangle with the sum of the area of > those > > 3 triangles > > if that comes out to be equal, then the point lies inside > > otherwise not. > > > > On Fri, Jul 29, 2011 at 1:34 AM, Don <[email protected]> wrote: > > > // True if point (x,y) is above line defined by two points > > > // If line is vertical, "above" is defined as to the right > > > bool above(double lx1, double ly1, double lx2, double ly2, double x, > > > double y) > > > { > > > return (lx1 != lx2) ? (y > (ly1+(x-lx1)*(ly2-ly1)/(lx2-lx1))) : (x > > > > lx1); > > > } > > > > > // True if point 1 and point 2 are on the same side of the line > > > defined by l1 and l2 > > > bool sameSide(double lx1, double ly1, double lx2, double ly2, double > > > px1, double py1, double px2, double py2) > > > { > > > return above(lx1, ly1, lx2, ly2, px1, py1) == above(lx1, ly1, lx2, > > > ly2, px2, py2); > > > } > > > > > // True if point (x,y) is inside triangle > > > bool pointInTriangle(double x1, double y1, double x2, double y2, > > > double x3, double y3, double x, double y) > > > { > > > return sameSide(x1,y1,x2,y2,x,y,x3,y3) && > > > sameSide(x1,y1,x3,y3,x,y,x2,y2) && > > > sameSide(x2,y2,x3,y3,x,y,x1,y1); > > > } > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Algorithm Geeks" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]. > > > For more options, visit this group at > > >http://groups.google.com/group/algogeeks?hl=en. > > > > > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
