/*
**  Usage:
**      inside = point_in_triangle(x0, y0, x1, y1, x2, y2, x3, y3);
**
**  Description:
**      Determines if a given point lays within a given triangle.
**
**  Arguments:
**      x0, y0    1st coordinate pair for the triangle
**      x1, y1    2nd coordinate pair for the triangle
**      x2, y2    3rd coordinate pair for the triangle
**      x3, y3    Coordinate pair of the test point
**
**  Returns:
**      TRUE when the test point is inside of the given triangle,
**      or FALSE otherwise.
**
**  Dependencies:
**      is_clockwise()
**
**  Notes:
**      Triangle coordinates should be given in traditional
**      counter-clockwise order.
**
**  copyright (c) 2006, John Leffingwell
**  www.planetxot.com
*/
var x0, y0, x1, y1, x2, y2, x3, y3;
x0 = argument[0];
y0 = argument[1];
x1 = argument[2];
y1 = argument[3];
x2 = argument[4];
y2 = argument[5];
x3 = argument[6];
y3 = argument[7];
return (not is_clockwise(x0,y0,x1,y1,x3,y3) && not is_clockwise(x1,y1,x2,y2,x3,y3) && not is_clockwise(x2,y2,x0,y0,x3,y3));