Physical Shadow Softness Parameter

[ecoskey]

Objective

Currently, directional lights use a non-physical soft_shadow_size value to determine soft shadows, in units of texels. This won't work with atmospherics, which needs a physical value for the angular size of the light to draw sun disks.

Solution

• replace soft_shadow_size with angular_size, which is no longer optional. This field describes the angular size of the light/sun, or the angle between one side of the sun and the other in the sky, through its center.

• Add new ShadowsStyle component:

pub enum ShadowsStyle {
  #[default]
  None, 
  Hard, 
  #[cfg(feature = "experimental_pbr_pcss")]
  Soft
}

• make all lights require ShadowsStyle

Testing

Tested pcss example, directional soft shadows don't work quite right. Hard shadows in other examples seem unaffected.

Migration Guide

The shadows_enabled and enable_soft_shadows fields have been removed from all lights. Add the ShadowsStyle::Hard component to a light to enable hard shadows, or ShadowsStyle::Soft to enable soft shadows (only with the experimental_pbr_pcss feature).

before:

commands.add(DirectionalLight {
  shadows_enabled: true,
  ..default()
});

after:

commands.add((
  DirectionalLight::default(),
  ShadowsStyle::Hard,
));

Instead of soft_shadow_size on directional lights, use angular_size. This field describes the angular size of the light/sun, or the angle between one side of the sun and the other in the sky, through its center. Its default value corresponds to the angular size of Earth's sun in the sky.

[JMS55]

I don't really like ShadowsStyle::Hard either tbh. Like for us it makes sense, but for new users I think "oh if you want to turn on shadows, you need Shadow::Hard" is weird. Especially because PCSS is more expensive and probably won't be used a ton. Maybe we could have { Off, On, Soft }? Or just keep the existing API, or split the component up or something, idk.