Drawing a polygon over a heatmap

Hi,
I would like to draw a polygon over a heatMap using an inherited class of UniformHeatMapDataSeries.
An example using FastHeatMapRenderableSeries was described here : https://wordpress-931910-4332701.cloudwaysapps.com/questions/wpf/drawing-a-polygon-upon-a-heatmap-chart ,but it is now deprecated since SciCharts V5.

Instead of that, i tried to declare an inherited class of CustomRenderableSeries as shown here :

public class PolygonRenderableSeries : CustomRenderableSeries {
protected override void Draw(IRenderContext2D renderContext, IRenderPassData renderPassData)
{
base.Draw(renderContext, renderPassData);
}
}

What i need now is to pass a List of Polygons to this class in order to draw them directly. I know how to draw a polygon, but i don’t know how to override the renderPassData for adding polygons to it.

Could you help me about that ?
Best regards,