Here is trendline generating script that has an input, Angle deg, that allows up to 89.999999999999 degrees to be set for an upward angle, and down to -89.999999999999 degrees to be set for a downward angle.
The input, Object name prefix, can be set/changed to avoid overwriting of a previous trendline and/or creating a channel by running the script more than once.
The trendline object can be dragged/moved by its anchor points but the angle will remain static.
Changing the chart timeframe, zooming, or scrolling will inherently change the angle of the trendline─anchor points remain fixed on the price-time continuum.
Files:
