This ProBuilder code snippet demonstrates how to draw a horizontal line on a chart at the highest high of the last 30 bars. This can be useful for visualizing resistance levels or significant price points over a given period.

DEFPARAM DRAWONLASTBARONLY = true
hh = highest[30](high)
DRAWSEGMENT(barindex-30,hh,barindex,hh)coloured(0,128,0,255)
RETURN

Here’s a step-by-step explanation of the code:

• DEFPARAM DRAWONLASTBARONLY = true: This line ensures that the drawing commands are executed only on the last bar of the chart. This is used to optimize performance by not redrawing on every bar update.
• hh = highest[30](high): This line calculates the highest value of the ‘high’ price over the last 30 bars and stores it in the variable ‘hh’.
• DRAWSEGMENT(barindex-30,hh,barindex,hh)coloured(0,128,0,255): This command draws a horizontal line (segment) from 30 bars ago to the current bar at the height of ‘hh’. The line is colored green with an RGBA value of (0, 128, 0, 255), where 255 represents full opacity.
• RETURN: This statement ends the script. It is often used for clarity, indicating that the script has finished executing its main functionality.

This example is particularly useful for traders or analysts who want to highlight significant price levels automatically without manually drawing lines on the chart.