# Layer Indication Code
At least for RGB Light, the `layer_state_set` function is used to detect the current highest layer, and change the underglow based on that layer.
This works for both the regular layers, and for the default layers, too.
I use the sethsv variants of the commands, so that different modes can be used, as well.
RGB Matrix uses a custom, per board implementation, at the moment.
# RGB Light Startup Animation
On startup, if enabled, the board will cycle through the entire hue wheel, starting and ending on the default layer color.
```c
void keyboard_post_init_rgb(void) {
#if defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_STARTUP_ANIMATION)
if (userspace_config.rgb_layer_change) { rgblight_enable_noeeprom(); }
if (rgblight_config.enable) {
layer_state_set_user(layer_state);
uint16_t old_hue = rgblight_config.hue;
rgblight_mode_noeeprom(RGBLIGHT_MODE_STATIC_LIGHT);
for (uint16_t i = 255; i > 0; i--) {
rgblight_sethsv_noeeprom( ( i + old_hue) % 255, 255, 255);
matrix_scan();
wait_ms(10);
}
}
#endif
layer_state_set_user(layer_state);
}
```
This could probably benefit from some cleanup and better handling.
# RGB Light Twinkling
This enables random twinkling of the LEDs when typing.
# RGB Light Mod Indicators
Allows feedback of which mods (oneshot or otherwise) are enabled.