Filters, sometimes called shaders allows us to use our Graphics Cards to create special visual effects.
PixelPAD2D gives us access to a collection of filters that we can use. To use them you just need to add them
to a GameObject, or the Game object itself.
add_filter(obj: GameObject, filter : Filter) -> filter id
Adds a filter to a game object, or globally if set to the Game object.
obj The game object to apply the filter on. You may also use the game object, which applies the filter globally
filter The filter to use. For example, you can create a new glow filter by calling new_glow_filter()