public void set_pick_with_alpha (bool pick_with_alpha)
Warning: set_pick_with_alpha is deprecated since 1.12.
Sets whether this should have it's shape defined by the alpha channel when picking.
There is no direct replacement for this function
Be aware that this is a bit more costly than the default picking due to the texture lookup, extra test against the alpha value and the fact that it will also interrupt the batching of geometry done internally.
Also there is currently no control over the threshold used to determine what value of alpha is considered pickable, and so only fully opaque parts of the texture will react to picking.