Trend Line Xross (TLX) Uses User Input Points to draw trendlines and displays the exact intersection point of those trendlines.
This is the public indicator of the practical application for this intersection method included in my entry for Pinefest #1.
To determine the exact intersection point I am using the y-intercept method as seen below.
The code is notated for more information on the technical workings.
One difference to note between this version and the pinefest version is that I had to change the line drawings to use bar_index values so that I can use line.get_price() to grab the current value of the line to make alerts from. Additionally, there are alerts built-in to this version for every type of cross on all of the visible lines.