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Bullet Hero
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Themes
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Themes

A theme is a palette of 64 colours that objects point at by slot number. How slots, references and theme keys work, and how to make, share and import a theme

A colour set to Theme stores no colour of its own, only a slot number. It takes whatever that slot holds in the theme active on the current frame. Change the theme and everything pointing at it changes with it

Why that beats literal colours, and how to keep a level readable under every theme - Colour, themes and post-processing

What a theme holds

  • A name - shown in the lists and pickers
  • An id, a ThemeId. Theme keys point at a theme by this id, not by its name
  • 64 colours on an 8 by 8 grid, each with transparency
  • A slot name for each slot, optional. Until you name a slot, the list of names is not written to the file

A theme is data inside level.json, not a file in resources (see What a level needs). A level can hold any number of themes

The 8 by 8 layout mirrors the one in Afterbeat. The game gives a slot no fixed role: the game's own Balanced theme simply groups its 64 colours by hue

How a colour finds its value

It takes two steps:

  1. The Theme track on the Events timeline says which theme is active on this frame
  2. A colour of type Theme names a slot from 0 to 63 in the active theme

Themeable colours include, for example, a shape's colour (each of its corners separately), a text's colour and the level background

A slot's position is its identity. Move a colour to another slot, and everything that pointed at the old one is restyled

Switching themes over time

Between two theme keys the game smoothly blends the whole palette from one theme to the other. The easing comes from the later key (see Keyframes and easing)

With no theme keys at all, every slot is white

Warning

A new key gets Linear, so the palette drifts across the whole stretch from the previous theme key to this one. For a switch exactly on the drop, set Constant on the key at the drop

Caution

A theme key can outlive its theme. Delete a theme that keys still point at, and every one of those frames turns white. The keys themselves stay. The editor asks before deleting such a theme

Making and editing a theme

The Themes tab among the level's resources lists the level's themes. It has Create and Import. Clicking a row opens the Theme Editor:

  • Name of the theme
  • Theme Id and Regenerate Id
  • the 8 by 8 grid. Clicking a cell selects it, shows Color: with its number and loads the colour into the wheel below
  • Slot name for the selected cell

The editor works on a copy. Nothing reaches the level until you save. The save itself is one undo step

Picking a slot

Switch a colour to Theme and open Select Theme Color

The grid shows the palette as it is blended on the frame of the key you are editing, not at the playhead. Beside it are the two theme keys around that frame and what the selected slot holds in each. An unnamed slot reads (unnamed)

Sharing and importing

  • The device library. A theme row's Export saves the theme into resources/themes - the device-wide library, with resources next to levels (see The level folder and backups). Theme Library lists it and marks what is already In Level. Delete removes a theme from the library. Importing copies the theme into the level, so the level never depends on your library
  • The game's own themes. Select Theme offers the themes that ship with the game next to the level's own
  • Afterbeat. Import .vgt turns an Afterbeat theme file into a level theme. Importing the same file again updates the theme rather than making a copy. Export .vgt writes every theme of the level into a folder you pick, one file per theme. Transparency is dropped, since Afterbeat theme colours carry none. Both buttons are hidden on Android, iOS and WebGL (see Importing from Afterbeat)

Next: Colour, themes and post-processing, Readability and fairness