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Currently, volumetric fog is global and affects the entire scene uniformly. This is inadequate for many use cases, such as local smoke effects. To address this problem, this commit introduces *fog volumes*, which are axis-aligned bounding boxes (AABBs) that specify fog parameters inside their boundaries. Such volumes can also specify a *density texture*, a 3D texture of voxels that specifies the density of the fog at each point. To create a fog volume, add a `FogVolume` component to an entity (which is included in the new `FogVolumeBundle` convenience bundle). Like light probes, a fog volume is conceptually a 1×1×1 cube centered on the origin; a transform can be used to position and resize this region. Many of the fields on the existing `VolumetricFogSettings` have migrated to the new `FogVolume` component. `VolumetricFogSettings` on a camera is still needed to enable volumetric fog. However, by itself `VolumetricFogSettings` is no longer sufficient to enable volumetric fog; a `FogVolume` must be present. Applications that wish to retain the old global fog behavior can simply surround the scene with a large fog volume. By way of implementation, this commit converts the volumetric fog shader from a full-screen shader to one applied to a mesh. The strategy is different depending on whether the camera is inside or outside the fog volume. If the camera is inside the fog volume, the mesh is simply a plane scaled to the viewport, effectively falling back to a full-screen pass. If the camera is outside the fog volume, the mesh is a cube transformed to coincide with the boundaries of the fog volume's AABB. Importantly, in the latter case, only the front faces of the cuboid are rendered. Instead of treating the boundaries of the fog as a sphere centered on the camera position, as we did prior to this patch, we raytrace the far planes of the AABB to determine the portion of each ray contained within the fog volume. We then raymarch in shadow map space as usual. If a density texture is present, we modulate the fixed density value with the trilinearly-interpolated value from that texture. Furthermore, this patch introduces optional jitter to fog volumes, intended for use with TAA. This modifies the position of the ray from frame to frame using interleaved gradient noise, in order to reduce aliasing artifacts. Many implementations of volumetric fog in games use this technique. Note that this patch makes no attempt to write a motion vector; this is because when a view ray intersects multiple voxels there's no single direction of motion. Consequently, fog volumes can have ghosting artifacts, but because fog is "ghostly" by its nature, these artifacts are less objectionable than they would be for opaque objects. A new example, `fog_volumes`, has been added. It demonstrates a single fog volume containing a voxelized representation of the Stanford bunny. The existing `volumetric_fog` example has been updated to use the new local volumetrics API. ## Changelog ### Added * Local `FogVolume`s are now supported, to localize fog to specific regions. They can optionally have 3D density voxel textures for precise control over the distribution of the fog. ### Changed * `VolumetricFogSettings` on a camera no longer enables volumetric fog; instead, it simply enables the processing of `FogVolume`s within the scene. ## Migration Guide * A `FogVolume` is now necessary in order to enable volumetric fog, in addition to `VolumetricFogSettings` on the camera. Existing uses of volumetric fog can be migrated by placing a large `FogVolume` surrounding the scene. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: François Mockers <mockersf@gmail.com> |
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What is Bevy?
Bevy is a refreshingly simple data-driven game engine built in Rust. It is free and open-source forever!
WARNING
Bevy is still in the early stages of development. Important features are missing. Documentation is sparse. A new version of Bevy containing breaking changes to the API is released approximately once every 3 months. We provide migration guides, but we can't guarantee migrations will always be easy. Use only if you are willing to work in this environment.
MSRV: Bevy relies heavily on improvements in the Rust language and compiler. As a result, the Minimum Supported Rust Version (MSRV) is generally close to "the latest stable release" of Rust.
Design Goals
- Capable: Offer a complete 2D and 3D feature set
- Simple: Easy for newbies to pick up, but infinitely flexible for power users
- Data Focused: Data-oriented architecture using the Entity Component System paradigm
- Modular: Use only what you need. Replace what you don't like
- Fast: App logic should run quickly, and when possible, in parallel
- Productive: Changes should compile quickly ... waiting isn't fun
About
- Features: A quick overview of Bevy's features.
- News: A development blog that covers our progress, plans and shiny new features.
Docs
- Quick Start Guide: Bevy's official Quick Start Guide. The best place to start learning Bevy.
- Bevy Rust API Docs: Bevy's Rust API docs, which are automatically generated from the doc comments in this repo.
- Official Examples: Bevy's dedicated, runnable examples, which are great for digging into specific concepts.
- Community-Made Learning Resources: More tutorials, documentation, and examples made by the Bevy community.
Community
Before contributing or participating in discussions with the community, you should familiarize yourself with our Code of Conduct.
- Discord: Bevy's official discord server.
- Reddit: Bevy's official subreddit.
- GitHub Discussions: The best place for questions about Bevy, answered right here!
- Bevy Assets: A collection of awesome Bevy projects, tools, plugins and learning materials.
Contributing
If you'd like to help build Bevy, check out the Contributor's Guide. For simple problems, feel free to open an issue or PR and tackle it yourself!
For more complex architecture decisions and experimental mad science, please open an RFC (Request For Comments) so we can brainstorm together effectively!
Getting Started
We recommend checking out the Quick Start Guide for a brief introduction.
Follow the Setup guide to ensure your development environment is set up correctly. Once set up, you can quickly try out the examples by cloning this repo and running the following commands:
# Switch to the correct version (latest release, default is main development branch)
git checkout latest
# Runs the "breakout" example
cargo run --example breakout
To draw a window with standard functionality enabled, use:
use bevy::prelude::*;
fn main(){
App::new()
.add_plugins(DefaultPlugins)
.run();
}
Fast Compiles
Bevy can be built just fine using default configuration on stable Rust. However for really fast iterative compiles, you should enable the "fast compiles" setup by following the instructions here.
Bevy Cargo Features
This list outlines the different cargo features supported by Bevy. These allow you to customize the Bevy feature set for your use-case.
Thanks
Bevy is the result of the hard work of many people. A huge thanks to all Bevy contributors, the many open source projects that have come before us, the Rust gamedev ecosystem, and the many libraries we build on.
A huge thanks to Bevy's generous sponsors. Bevy will always be free and open source, but it isn't free to make. Please consider sponsoring our work if you like what we're building.
This project is tested with BrowserStack.
License
Bevy is free, open source and permissively licensed! Except where noted (below and/or in individual files), all code in this repository is dual-licensed under either:
- MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
at your option. This means you can select the license you prefer! This dual-licensing approach is the de-facto standard in the Rust ecosystem and there are very good reasons to include both.
Some of the engine's code carries additional copyright notices and license terms due to their external origins.
These are generally BSD-like, but exact details vary by crate:
If the README of a crate contains a 'License' header (or similar), the additional copyright notices and license terms applicable to that crate will be listed.
The above licensing requirement still applies to contributions to those crates, and sections of those crates will carry those license terms.
The license field of each crate will also reflect this.
For example, bevy_mikktspace has code under the Zlib license (as well as a copyright notice when choosing the MIT license).
The assets included in this repository (for our examples) typically fall under different open licenses. These will not be included in your game (unless copied in by you), and they are not distributed in the published bevy crates. See CREDITS.md for the details of the licenses of those files.
Your contributions
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.