Day/Night system FAQ
Q: How do I disable DNS?
A: Set OW_ENABLE_DNS to FALSE in include/config/overworld.h.
Q: What map changes should be made for DNS?
A: By default, the only Hoenn map changes that need to be made are to edit the Lavaridge Town map to change the metatiles the two old ladies are on in the hot springs to be the normal hot spring water tile. This is to avoid a visual bug from when OW_OBJECT_VANILLA_SHADOWS is FALSE.
However, by default no maps have lighting effects of any kind. The rest of this tutorial is to aid in adding lighting effects.
If you intend to use vanilla maps and have not already edited them, revert commit a5b079d833f18f66ebd53ac77f00227ae4a1f389. This commit includes a lot of tileset, metatile, and palette changes to accommodate light-blending, and applies OBJ_EVENT_GFX_LIGHT_SPRITE where they make sense.
If you have edited vanilla maps, the merge conflicts from reverting that commit will cause problems. If you are using vanilla maps, manually copy some of the tileset changes, .pal, and .pla files in your branch, and begin rebuilding your metatiles to have windows use the palettes that have a .pla for light blending the correct color slots. Triple-layer metatiles are highly recommended.
You will also want to add the lighting object events from that commit.
If you are not using Hoenn maps, the primary concern is that you do not use the exact same palette indices for colors you want to be darkened during night time and colors you want to light up. Err towards not light blending a color if you aren't sure how to avoid conflicts.
When writing map scripts, fadescreenswapbuffers should be preferred over fadescreen. This is to avoid odd behavior from the GBA's limitations in alpha blending.
Q: How do I make lightbulbs glow?
A: Making lamps glow is not part of the tileset itself. Instead, place certain object events on top of where you desire a glowing effect.
These object events should use OBJ_EVENT_GFX_LIGHT_SPRITE and then as their trainer_sight_or_berry_tree_id (called Sight Radius/Berry Tree ID in porymap), use LIGHT_TYPE_BALL for round lights (such as candles or gas lamps), LIGHT_TYPE_PKMN_CENTER_SIGN over a Pokémon Center sign, or LIGHT_TYPE_POKE_MART_SIGN over a Pokémart sign.
Q: How do I mark certain colors in a palette as light-blended?
A: Create a .pla file in the same folder as the .pal with the same name. This can be done on any kind of palette; the commit to revert listed up above only applies it to tilesets, but you could easily do it for object events as well. Of note, there is a commit reverted for being out of scope to make a follower Ampharos's tail glow.
In this file you can enter color indices [0,15] on separate lines to mark those colors as being light-blended, i.e:
06.pla:
# A comment
0 # if color 0 is listed, uses it to blend with instead of the default!
1
9
10
During the day time, these color indices appear as normal, but will be blended with either yellow or the 0 index at night. These indices should only be used for things you expect to light up. If you are using porytiles, palette overrides and using slight alterations to a color will aid you in avoiding color conflicts where the wrong index is assigned.
The windows appear as normal during the day time (blue) and light up in the night. These use the default color.
Q: How do I return to using regular shadows?
A: Set OW_OBJECT_VANILLA_SHADOWS to TRUE in include/config/overworld.h.
Q: What graphical errors are likely to occur while using DNS?
A: If you have OW_POPUP_GENERATION set to GEN_5 and OW_POPUP_BW_ALPHA_BLEND set to TRUE, you may have color errors during map popups. This is due to the GBA being severely limited in use of color blending and having both the overworld blended and the popup blended is difficult.
If you have OW_OBJECT_VANILLA_SHADOWS set to TRUE, this will also cause visual errors.
Any other graphical error should be reported.
Q: How do I disable shadows for certain locations?
A: Shadows can be disabled for certain locations by modifying the CurrentMapHasShadows function in src/overworld.c.