diff --git a/crates/bevy_pbr/src/pbr_material.rs b/crates/bevy_pbr/src/pbr_material.rs index 9c988bf1ed0fe..5f6314b9a11b5 100644 --- a/crates/bevy_pbr/src/pbr_material.rs +++ b/crates/bevy_pbr/src/pbr_material.rs @@ -78,16 +78,25 @@ pub struct StandardMaterial { /// /// The default emissive color is [`LinearRgba::BLACK`], which doesn't add anything to the material color. /// - /// To increase emissive strength, channel values for `emissive` + /// Emissive strength is controlled by the value of the color channels, + /// while the hue is controlled by their relative values. + /// + /// As a result, channel values for `emissive` /// colors can exceed `1.0`. For instance, a `base_color` of /// `LinearRgba::rgb(1.0, 0.0, 0.0)` represents the brightest /// red for objects that reflect light, but an emissive color /// like `LinearRgba::rgb(1000.0, 0.0, 0.0)` can be used to create /// intensely bright red emissive effects. /// + /// This results in a final luminance value when multiplied + /// by the value of the greyscale emissive texture (which ranges from 0 for black to 1 for white). + /// Luminance is a measure of the amount of light emitted per unit area, + /// and can be thought of as the "brightness" of the effect. + /// In Bevy, we treat these luminance values as the physical units of cd/m², aka nits. + /// /// Increasing the emissive strength of the color will impact visual effects /// like bloom, but it's important to note that **an emissive material won't - /// light up surrounding areas like a light source**, + /// typically light up surrounding areas like a light source**, /// it just adds a value to the color seen on screen. pub emissive: LinearRgba,