# Objective
One thing missing from the new Color implementation in 0.14 is the
ability to easily convert to a u8 representation of the rgb color.
(note this is a redo of PR https://github.com/bevyengine/bevy/pull/13739
as I needed to move the source branch
## Solution
I have added to_u8_array and to_u8_array_no_alpha to a new trait called
ColorToPacked to mirror the f32 conversions in ColorToComponents and
implemented the new trait for Srgba and LinearRgba.
To go with those I also added matching from_u8... functions and
converted a couple of cases that used ad-hoc implementations of that
conversion to use these.
After discussion on Discord of the experience of using the API I renamed
Color::linear to Color::to_linear, as without that it looks like a
constructor (like Color::rgb).
I also added to_srgba which is the other commonly converted to type of
color (for UI and 2D) to match to_linear.
Removed a redundant extra implementation of to_f32_array for LinearColor
as it is also supplied in ColorToComponents (I'm surprised that's
allowed?)
## Testing
Ran all tests and manually tested.
Added to_and_from_u8 to linear_rgba::tests
## Changelog
visible change is Color::linear becomes Color::to_linear.
---------
Co-authored-by: John Payne <20407779+johngpayne@users.noreply.github.com>
# Objective
- Fixes#13521
## Solution
Set `ambient_intensity` to 0.0 in volumetric_fog example.
I chose setting it explicitly over changing the default in order to make
it clear that this needs to be set depending on whether you have an
`EnvironmentMapLight`. See documentation for `ambient_intensity` and
related members.
## Testing
- Run the volumetric_fog example and notice how the light shown in
#13521 is not there anymore, as expected.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- #13418 broke volumetric fog
```
wgpu error: Validation Error
Caused by:
In a RenderPass
note: encoder = `<CommandBuffer-(2, 4, Metal)>`
In a set_bind_group command
note: bind group = `mesh_view_bind_group`
Bind group 0 expects 5 dynamic offsets. However 4 dynamic offsets were provided.
```
## Solution
- add ssr offset to volumetric fog bind group
This commit implements a more physically-accurate, but slower, form of
fog than the `bevy_pbr::fog` module does. Notably, this *volumetric fog*
allows for light beams from directional lights to shine through,
creating what is known as *light shafts* or *god rays*.
To add volumetric fog to a scene, add `VolumetricFogSettings` to the
camera, and add `VolumetricLight` to directional lights that you wish to
be volumetric. `VolumetricFogSettings` has numerous settings that allow
you to define the accuracy of the simulation, as well as the look of the
fog. Currently, only interaction with directional lights that have
shadow maps is supported. Note that the overhead of the effect scales
directly with the number of directional lights in use, so apply
`VolumetricLight` sparingly for the best results.
The overall algorithm, which is implemented as a postprocessing effect,
is a combination of the techniques described in [Scratchapixel] and
[this blog post]. It uses raymarching in screen space, transformed into
shadow map space for sampling and combined with physically-based
modeling of absorption and scattering. Bevy employs the widely-used
[Henyey-Greenstein phase function] to model asymmetry; this essentially
allows light shafts to fade into and out of existence as the user views
them.
Volumetric rendering is a huge subject, and I deliberately kept the
scope of this commit small. Possible follow-ups include:
1. Raymarching at a lower resolution.
2. A post-processing blur (especially useful when combined with (1)).
3. Supporting point lights and spot lights.
4. Supporting lights with no shadow maps.
5. Supporting irradiance volumes and reflection probes.
6. Voxel components that reuse the volumetric fog code to create voxel
shapes.
7. *Horizon: Zero Dawn*-style clouds.
These are all useful, but out of scope of this patch for now, to keep
things tidy and easy to review.
A new example, `volumetric_fog`, has been added to demonstrate the
effect.
## Changelog
### Added
* A new component, `VolumetricFog`, is available, to allow for a more
physically-accurate, but more resource-intensive, form of fog.
* A new component, `VolumetricLight`, can be placed on directional
lights to make them interact with `VolumetricFog`. Notably, this allows
such lights to emit light shafts/god rays.
[Scratchapixel]:
https://www.scratchapixel.com/lessons/3d-basic-rendering/volume-rendering-for-developers/intro-volume-rendering.html
[this blog post]: https://www.alexandre-pestana.com/volumetric-lights/
[Henyey-Greenstein phase function]:
https://www.pbr-book.org/4ed/Volume_Scattering/Phase_Functions#TheHenyeyndashGreensteinPhaseFunction
