Swizzle

trait Swizzle:
  .doc: """
When this trait is applied to a texture, it signals that the texture channels should
be reordered before the texture is accessed. This is commonly used when multiple
property maps are packed into different color channels of the same texture.
For instance, when using ORM (Occlusion, Roughness, Metallic) maps where the
property maps are baked into the r,g,b channels of a single texture respectively.

Valid values for the swizzle will depend on the source texture:
- If the source texture has 4 channels, the characters should be from the set
  [r,g,b,a], if it has 2, only [r, g] are properly defined.
- The length of the swizzle should not exceed 4 characters and will affect the output
  channels. i.e. a swizzle of length 3 will output a texture with 3 channels.
"""
  swizzle is String