Icons

Icons are PNG files in icon/, such as icon/food/Cake.png. Every PNG in icon/ is an icon, so to add one, add a PNG there. Save each icon as an indexed PNG with at most 16 colors, or as an RGBA PNG with no more than 32 levels in each color channel and no partly transparent pixels. An icon that has a disabled version must be an indexed PNG with at most 16 colors.

Item icons

An item uses the icon that its icon field in registry/items.yaml names, which is the icon's path without .png:

    icon: food/Cake

The game shows that icon everywhere it draws the item, such as in menus, in the world, and in text boxes, so the icon field is all an item needs. To show an item's icon from your own code, create a HUD element from its HudScript in gItemHudScripts. Only the battle and pause menu headers declare gItemHudScripts, so in other code, declare it yourself:

extern IconHudScriptPair gItemHudScripts[];

HudElemID hid = hud_element_create(gItemHudScripts[gItemTable[ITEM_CAKE].hudElemID].enabled);

Disabled icons

Menus show an item's disabled icon when you can't use the item. To give an icon one, save a second PNG beside it named <name>.disabled.png, such as food/Cake.disabled.png. It must be the same image with a different palette, because the game draws the main icon's pixels with the disabled icon's colors.