The DRAWRAY function in ProBuilder language is used to plot a ray on a chart. A ray is a line segment that starts at a specified point and extends infinitely in one direction. This function is particularly useful for highlighting trends or potential levels of support and resistance on a price chart.

Syntax:

DRAWRAY(x1, y1, x2, y2) COLOURED(R, G, B, a)

The DRAWRAY function requires four coordinates: x1 and y1 define the starting point of the ray, while x2 and y2 indicate the direction in which the ray extends. The ray will extend towards the direction of the second point from the first point. The COLOURED function is optional and can be used to specify the color and transparency of the ray using RGB color values and an alpha (transparency) value.

Example Usage:

To demonstrate the use of DRAWRAY, consider plotting two trend lines based on the highest high and lowest low over a certain period:

defparam drawonlastbaronly = true
period = 70

if islastbarupdate then
    y2 = lowest[period](low)
    yy2 = highest[period](high)

    // Find the bar index of the highest high and lowest low for the period
    for i = 0 to period do
        if low[i] = y2 then
            x2 = barindex[i]
        endif
        if high[i] = yy2 then
            xx2 = barindex[i]
        endif
    next

    // Find the bar index of the highest high and lowest low for half the period
    for i = 0 to round(period/2) do
        if low[i] < y2 then
            y1 = low[i]
            x1 = barindex[i]
        else
            y1 = low
            x1 = barindex
        endif
        if high[i] > yy2 then
            yy1 = high[i]
            xx1 = barindex[i]
        else
            yy1 = high
            xx1 = barindex
        endif
    next

    // Plot the two half segments (rays)
    DRAWray(x1, y1, x2, y2) coloured(255, 10, 10)
    DRAWray(xx1, yy1, xx2, yy2) coloured(255, 10, 10)
endif

This example sets up two rays based on dynamic calculations of highs and lows over a specified period and half of that period. The rays are colored red with RGB values (255, 10, 10).

Additional Information:

• The direction of the ray depends on the order of the coordinate pairs. If x1, y1 are to the right of x2, y2, the ray will extend to the left, and vice versa.
• Using COLOURED is optional but helpful for distinguishing different rays or trends on the chart.

This function is a powerful tool in technical analysis for visualizing and extending key levels or trends directly on trading charts.