!EXPERIMENTAL!
As TV doesn't provide a function to draw lines between points, I wrote a function to do this in one my own indicators.
The function itself however can be applied/modified for different use cases, eg. drawing trendlines.
In this (proof of concept) example I used it to draw lines based on past high/low pivot points.
The inputs required:
* an INPUT FUNCTION (in this form, its designed to work with functions that have occasional values and na-values between them, it then connects the non-zero values to form a line)
* a BOOL (to indicate if you want to draw only the rising or falling lines)
* a DELAY (in this case this is the lookback period for the pivot-points function, this is to compensate the calculation of the past and realtime points)
The function returns:
* the function to draw the extension from the BASE-LINE to the current time (here this is the connection of the last pivot-point to the current point to bridge the gap of the lookback period, this is NOT REALTIME!)
* the function to draw the extension for the current time (here this is the continuation of the line until a new pivot-point is valid, this is DRAWN IN REALTIME!!)
* the color of the lines (in this case the lines are only colored (lime or fuchsia) if they either go up or down, else they are invisible, this is to clean up the invalid lines)
these output functions can then simply be plotted using the 'plot' function.
JD.