bevy/assets
Jiří Švejda 510fce9af3
Allow fog density texture to be scrolled over time with an offset (#14868)
# Objective

- The goal of this PR is to make it possible to move the density texture
of a `FogVolume` over time in order to create dynamic effects like fog
moving in the wind.
- You could theoretically move the `FogVolume` itself, but this is not
ideal, because the `FogVolume` AABB would eventually leave the area. If
you want an area to remain foggy while also creating the impression that
the fog is moving in the wind, a scrolling density texture is a better
solution.

## Solution

- The PR adds a `density_texture_offset` field to the `FogVolume`
component. This offset is in the UVW coordinates of the density texture,
meaning that a value of `(0.5, 0.0, 0.0)` moves the 3d texture by half
along the x-axis.
- Values above 1.0 are wrapped, a 1.5 offset is the same as a 0.5
offset. This makes it so that the density texture wraps around on the
other side, meaning that a repeating 3d noise texture can seamlessly
scroll forever. It also makes it easy to move the density texture over
time by simply increasing the offset every frame.

## Testing

- A `scrolling_fog` example has been added to demonstrate the feature.
It uses the offset to scroll a repeating 3d noise density texture to
create the impression of fog moving in the wind.
- The camera is looking at a pillar with the sun peaking behind it. This
highlights the effect the changing density has on the volumetric
lighting interactions.
- Temporal anti-aliasing combined with the `jitter` option of
`VolumetricFogSettings` is used to improve the quality of the effect.

---

## Showcase


https://github.com/user-attachments/assets/3aa50ebd-771c-4c99-ab5d-255c0c3be1a8
2024-08-22 19:43:14 +00:00
..
android-res/mipmap-mdpi android example polish (#845) 2020-11-11 16:31:16 -08:00
animation_graphs Implement the AnimationGraph, allowing for multiple animations to be blended together. (#11989) 2024-03-07 20:22:42 +00:00
branding Remove unused namespace declarations (#10965) 2023-12-13 22:29:16 +00:00
data Added Support for Extension-less Assets (#10153) 2024-01-31 14:58:08 +00:00
docs Improve Mesh documentation (#9061) 2023-07-31 18:55:42 +00:00
environment_maps Implement minimal reflection probes (fixed macOS, iOS, and Android). (#11366) 2024-01-19 07:33:52 +00:00
fonts Add the license for the FiraMono font (#3589) 2022-05-06 19:29:43 +00:00
irradiance_volumes Implement irradiance volumes. (#10268) 2024-02-06 23:23:20 +00:00
lightmaps Implement lightmaps. (#10231) 2024-01-02 20:38:47 +00:00
models Use a ship in Transform::align example (#13935) 2024-06-20 00:58:00 +00:00
pixel Add example for pixel-perfect grid snapping in 2D (#8112) 2023-12-26 17:15:50 +00:00
scenes Fix scene example (#11289) 2024-01-22 15:14:41 +00:00
shaders Add example showing how to use SpecializedMeshPipeline (#14370) 2024-07-31 18:24:58 +00:00
sounds Programmed soundtrack example (#12774) 2024-03-29 20:32:30 +00:00
textures Implement opt-in sharp screen-space reflections for the deferred renderer, with improved raymarching code. (#13418) 2024-05-27 13:43:40 +00:00
volumes Allow fog density texture to be scrolled over time with an offset (#14868) 2024-08-22 19:43:14 +00:00