# Objective
Order independent transparency can filter fragment writes based on the
alpha value and it is currently hard-coded to anything higher than 0.0.
By making that value configurable, users can optimize fragment writes,
potentially reducing the number of layers needed and improving
performance in favor of some transparency quality.
## Solution
This PR adds `alpha_threshold` to the
OrderIndependentTransparencySettings component and uses the struct to
configure a corresponding shader uniform. This uniform is then used
instead of the hard-coded value.
To configure OIT with a custom alpha threshold, use:
```rust
fn setup(mut commands: Commands) {
commands.spawn((
Camera3d::default(),
OrderIndependentTransparencySettings {
layer_count: 8,
alpha_threshold: 0.2,
},
));
}
```
## Testing
I tested this change using the included OIT example, as well as with two
additional projects.
## Migration Guide
If you previously explicitly initialized
OrderIndependentTransparencySettings with your own `layer_count`, you
will now have to add either a `..default()` statement or an explicit
`alpha_threshold` value:
```rust
fn setup(mut commands: Commands) {
commands.spawn((
Camera3d::default(),
OrderIndependentTransparencySettings {
layer_count: 16,
..default()
},
));
}
```
---------
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
222483daaa