Animation overlays

Basic idea

Add small graphics to buildings depending on their inventory. Imagine lumberjack having a pile of boards around.

FIFE supports this now: fifengine/fifengine#201

How to test

• FIFE git
• UH branch overlays
• Check [InventoryOverlayComponent] (https://github.com/unknown-horizons/unknown-horizons/blob/overlays/horizons/component/inventoryoverlaycomponent.py) and [the images] (http://git.io/GByH2w)

Design

Animation overlays are unique per action set (as_...) and per action (idle). Currently only adding overlays to idle.

The component depends on StorageComponent for listening to messages whenever inventory updates happen.

• Fallback mechanism: For new_amount = 3 and defined overlays 0: None, 2: 'boards_2', 5: 'boards_12' we use 'boards_2' as overlay.
• Use null in yaml for "no overlay at all" (translates to None in python)

Example for lumberjack in tier Pioneers:

- InventoryOverlayComponent:
    overlays:
      as_lumberjack_barrack0:
       #idle:  <-- does not exist yet but will be necessary later
        RES.BOARDS:
          - [0, null]
          - [1, planks_01] # ...
          - [8, planks_08]
          - [9, planks_10]
          - [10, planks_12]
        RES.TREES:
          - [0, null]
          - [1, logs_01]
          - [3, logs_02] # ...
          - [9, logs_05]

Additional

• Fields show their status using idle_full actions instead (last animation step), so they do not need overlays
• Other buildings do not store physical resources, or uninteresting ones. Do not show overlays for those. What about the farm with the huge amount of possible resources there? Generic like with storages?
• Unit producers (which can store large amounts of multiple resources) should combine some of the levels to reduce visual clutter. E.g. boat builder (12 tons of four resources) shows nothing/1-4/5-8/9-12 or even 1-6/7-12
• Storage buildings could display generic boxes, barrels, etc. to indicate collector utilization

Test buildings

Buildings to test this feature with (by priority, most useful first)

Implemented	Building	Resource
yes (both)	lumberjack	boards and logs, [only logs in Sailors] (https://github.com/unknown-horizons/unknown-horizons/blob/master/content/gfx/buildings/sailors/lumberjack/as_lumberjack0/idle/135/0.png)

       | brickyard            | bricks (needs new work animation then)
       | smeltery             | iron and [other stuff on the left] (https://github.com/unknown-horizons/           | unknown-horizons/blob/master/content/gfx/buildings/settlers/smeltery/as_smeltery0/idle/315/0.png)
       | boat builder         | boards, with extra code (ship progress as resource in BB inventory) also ship
       | salt ponds           | salt barrels (needs new work animation without the barrels then)
       | tobacconist          | tobaccos
       | butchery             | meat
       | tower                | cannons

More ideas: brewery, bakery, clay pit, windmill, ...