Transparency

trait Transparency:
    .doc: """
Defines a material as being partially transparent either across the entire surface
or in certain parts as defined by the alpha_map.

It is common to use a single texture for base_color and alpha values which can be achieved
using a swizzle operation on the alpha_map texture.

If an alpha_map is provided, the sampled values is scaled by the constant alpha value.
Otherwise, the alpha value is used as is.
"""
    alpha is Real: 1.0
    alpha_map is Visuals.Textures.DefaultTexture

    # Propagate outer values to the physical visible light spectrum band
    visible becomes Visuals.Optics.VisibleBand with Visuals.Optics.SurfaceFeatures.Transparency:
        alpha: alpha
        alpha_map: alpha_map