In openlayers there are 2 paradigms for drawing features one is to create a "draw interaction" that lets the user draw a feature and the other is to create the geometry and feature yourself--then add it to the layer.
I would like to programmatically start a polygon "interaction" drawing for the user by placing the first point. After which the user will place the remaining points. It therefore must be an "interaction".
This means I must simulate a user click or draw event that the openlayers api accepts as valid.
map.dispatchEvent(<clickevent>) map.dispatchEvent(<drawstartevent>) /*draw being ol.interaction.Draw*/ draw.dispatchEvent(<clickevent>) draw.dispatchEvent(<drawstartevent>)