bevy_render/
alpha.rs

1use bevy_reflect::{std_traits::ReflectDefault, Reflect};
2
3// TODO: add discussion about performance.
4/// Sets how a material's base color alpha channel is used for transparency.
5#[derive(Debug, Default, Reflect, Copy, Clone, PartialEq)]
6#[reflect(Default, Debug)]
7pub enum AlphaMode {
8    /// Base color alpha values are overridden to be fully opaque (1.0).
9    #[default]
10    Opaque,
11    /// Reduce transparency to fully opaque or fully transparent
12    /// based on a threshold.
13    ///
14    /// Compares the base color alpha value to the specified threshold.
15    /// If the value is below the threshold,
16    /// considers the color to be fully transparent (alpha is set to 0.0).
17    /// If it is equal to or above the threshold,
18    /// considers the color to be fully opaque (alpha is set to 1.0).
19    Mask(f32),
20    /// The base color alpha value defines the opacity of the color.
21    /// Standard alpha-blending is used to blend the fragment's color
22    /// with the color behind it.
23    Blend,
24    /// Similar to [`AlphaMode::Blend`], however assumes RGB channel values are
25    /// [premultiplied](https://en.wikipedia.org/wiki/Alpha_compositing#Straight_versus_premultiplied).
26    ///
27    /// For otherwise constant RGB values, behaves more like [`AlphaMode::Blend`] for
28    /// alpha values closer to 1.0, and more like [`AlphaMode::Add`] for
29    /// alpha values closer to 0.0.
30    ///
31    /// Can be used to avoid “border” or “outline” artifacts that can occur
32    /// when using plain alpha-blended textures.
33    Premultiplied,
34    /// Spreads the fragment out over a hardware-dependent number of sample
35    /// locations proportional to the alpha value. This requires multisample
36    /// antialiasing; if MSAA isn't on, this is identical to
37    /// [`AlphaMode::Mask`] with a value of 0.5.
38    ///
39    /// Alpha to coverage provides improved performance and better visual
40    /// fidelity over [`AlphaMode::Blend`], as Bevy doesn't have to sort objects
41    /// when it's in use. It's especially useful for complex transparent objects
42    /// like foliage.
43    ///
44    /// [alpha to coverage]: https://en.wikipedia.org/wiki/Alpha_to_coverage
45    AlphaToCoverage,
46    /// Combines the color of the fragments with the colors behind them in an
47    /// additive process, (i.e. like light) producing lighter results.
48    ///
49    /// Black produces no effect. Alpha values can be used to modulate the result.
50    ///
51    /// Useful for effects like holograms, ghosts, lasers and other energy beams.
52    Add,
53    /// Combines the color of the fragments with the colors behind them in a
54    /// multiplicative process, (i.e. like pigments) producing darker results.
55    ///
56    /// White produces no effect. Alpha values can be used to modulate the result.
57    ///
58    /// Useful for effects like stained glass, window tint film and some colored liquids.
59    Multiply,
60}
61
62impl Eq for AlphaMode {}
bevy_render/alpha.rs

bevy_render/
alpha.rs
