Commit graph

623 commits

Author SHA1 Message Date
Michael Hills
040ad7f5a4 Add audio to ios example (#1007)
I'm still here :) will try to land the ios audio support in cpal soon and then we can land this.

This PR also adds in assets as a directory reference and avoids the "Xcode is optimizing and breaking my PNGs" issue that I had earlier on during iOS testing on Bevy.

Re-testing this now.
2021-05-30 18:39:31 +00:00
Andreas Weibye
44f64a32f4 CI - Check that examples are listed in README and Cargo (#1650)
Closes #1581 

# Internal File/Link Consistency checker Action

This pull request adds an action to the CI that parses the [`./examples`](https://github.com/bevyengine/bevy/tree/main/examples) folder for files and cross references that with the links listed in [`README.md`](https://github.com/bevyengine/bevy/blob/main/examples/README.md) and [`Cargo.toml`](https://github.com/bevyengine/bevy/blob/main/Cargo.toml) to ensure the documentation actually reflects the examples currently in the repo. 

The primary reason for why we want this, is to prevent people from adding new examples but forgetting to also list them in the docs, or accidentally entering broken links (typos in docs).

For details on how the action is working: [Check out the README here](https://github.com/Weibye/action-internal-link-consistency/blob/main/README.md)

Co-authored-by: Andreas Weibye <13300393+Weibye@users.noreply.github.com>
2021-05-30 18:14:58 +00:00
Federico Rinaldi
4f34143046 Add iter_combinations to examples' README.md (#2266)
Added a short description of the example.

Fixes #2263.
2021-05-29 01:30:28 +00:00
Daniel Borges
5cccba5d21 Fixed a comment in the fixed timestep example (#2245)
Co-authored-by: Daniel Borges <daniel@manufacture43.com>
2021-05-24 20:05:36 +00:00
the-notable
9f94f7eb6c Example showing how to use AsyncComputeTaskPool and Tasks (#2180) 2021-05-23 20:13:55 +00:00
Paweł Grabarz
a81fb7aa7e Add a method iter_combinations on query to iterate over combinations of query results (#1763)
Related to [discussion on discord](https://discord.com/channels/691052431525675048/742569353878437978/824731187724681289)

With const generics, it is now possible to write generic iterator over multiple entities at once.

This enables patterns of query iterations like

```rust
for [e1, e2, e3] in query.iter_combinations() {
   // do something with relation of all three entities
}
```

The compiler is able to infer the correct iterator for given size of array, so either of those work
```rust
for [e1, e2] in query.iter_combinations()  { ... }
for [e1, e2, e3] in query.iter_combinations()  { ... }
```

This feature can be very useful for systems like collision detection.

When you ask for permutations of size K of N entities:
- if K == N, you get one result of all entities
- if K < N, you get all possible subsets of N with size K, without repetition
- if K > N, the result set is empty (no permutation of size K exist)

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-05-17 23:33:47 +00:00
Aevyrie
85b17294b9 Fix PBR regression for unlit materials (#2197)
Fixes the frag shader for unlit materials by correcting the scope of the `#ifndef` to include the light functions. Closes #2190, introduced in #2112.

Tested by changing materials in the the `3d_scene` example to be unlit. Unsure how to prevent future regressions without creating a test case scene that will catch these runtime panics.
2021-05-17 22:45:07 +00:00
Nathan Ward
e3435e5144 fix scenes-example unread field warning (#2179)
This should fix CI error: https://github.com/bevyengine/bevy/pull/2175/checks?check_run_id=2592736553
2021-05-16 18:09:47 +00:00
giusdp
cdae95b4b8 Add exit_on_esc_system to examples with window (#2121)
This covers issue #2110

It adds the line `.add_system(bevy::input::system::exit_on_esc_system.system())` before `.run()`
to every example that uses a window, so users have a quick way to close the examples.

I used the full name `bevy::input::system::exit_on_esc_system`, I thought it gave clarity about being a built-in system.

The examples excluded from the change are the ones in the android, ios, wasm folders, the headless 
examples and the ecs/system_sets example because it closes itself.
2021-05-14 20:15:54 +00:00
FlyingRatBull
ff4acee9e1 [DOC] Mention FPS in log_diagnostics example (#2150)
Closes #2076
2021-05-14 18:26:09 +00:00
Denis Laprise
7d0e98f34c Implement rotation for Text2d (#2084)
Fixes https://github.com/bevyengine/bevy/issues/2080

![CleanShot 2021-05-02 at 22 50 09](https://user-images.githubusercontent.com/11653/116844876-373ca780-ab99-11eb-8f61-8d93d929bff0.gif)


Co-authored-by: Nathan Stocks <cleancut@github.com>
Co-authored-by: Denis Laprise <nside@users.noreply.github.com>
2021-05-06 03:55:55 +00:00
François
afaf4ad3da update for wgpu 0.8 (#1959)
Changes to get Bevy to compile with wgpu master.

With this, on a Mac:
* 2d examples look fine
* ~~3d examples crash with an error specific to metal about a compilation error~~
* 3d examples work fine after enabling feature `wgpu/cross`


Feature `wgpu/cross` seems to be needed only on some platforms, not sure how to know which. It was introduced in https://github.com/gfx-rs/wgpu-rs/pull/826
2021-05-02 20:45:25 +00:00
FlyingRatBull
b399a374cb GitHub Action: Check local Markdown links on push (#2067)
Adds an GitHub Action to check all local (non http://, https:// ) links in all Markdown files of the repository for liveness.
Fails if a file is not found.

# Goal
This should help maintaining the quality of the documentation.

# Impact
Takes ~24 seconds currently and found 3 dead links (pull requests already created).

# Dependent PRs
* #2064 
* #2065 
* #2066

# Info
See [markdown-link-check](https://github.com/marketplace/actions/markdown-link-check).

# Example output
```
FILE: ./docs/profiling.md

1 links checked.

FILE: ./docs/plugins_guidelines.md

37 links checked.

FILE: ./docs/linters.md
[✖] ../.github/linters/markdown-lint.yml → Status: 400 [Error: ENOENT: no such file or directory, access '/github/workspace/.github/linters/markdown-lint.yml'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'access',
  path: '/github/workspace/.github/linters/markdown-lint.yml'
}
```

# Improvements
* Can also be used to check external links, but fails because of:
  * Too many requests (429) responses:
```
FILE: ./CHANGELOG.md
[✖] https://github.com/bevyengine/bevy/pull/1762 → Status: 429
```
   * crates.io links respond 404
```
FILE: ./README.md
[✖] https://crates.io/crates/bevy → Status: 404
```
2021-05-02 20:22:32 +00:00
FlyingRatBull
82014a3abd Fix broken link to touch_input_events example (#2066) 2021-05-01 18:51:55 +00:00
FlyingRatBull
4e5210f8e9 Fix broken link to PBR example in README.md (#2064) 2021-05-01 18:51:54 +00:00
CGMossa
86ad5bf420 Adding WorldQuery for WithBundle (#2024)
In response to #2023, here is a draft for a PR. 

Fixes #2023

I've added an example to show how to use `WithBundle`, and also to test it out. 

Right now there is a bug: If a bundle and a query are "the same", then it doesn't filter out
what it needs to filter out. 

Example: 

```
Print component initated from bundle.
[examples/ecs/query_bundle.rs:57] x = Dummy( <========= This should not get printed
    111,
)
[examples/ecs/query_bundle.rs:57] x = Dummy(
    222,
)
Show all components
[examples/ecs/query_bundle.rs:50] x = Dummy(
    111,
)
[examples/ecs/query_bundle.rs:50] x = Dummy(
    222,
)
```

However, it behaves the right way, if I add one more component to the bundle,
so the query and the bundle doesn't look the same:

```
Print component initated from bundle.
[examples/ecs/query_bundle.rs:57] x = Dummy(
    222,
)
Show all components
[examples/ecs/query_bundle.rs:50] x = Dummy(
    111,
)
[examples/ecs/query_bundle.rs:50] x = Dummy(
    222,
)
```

I hope this helps. I'm definitely up for tinkering with this, and adding anything that I'm asked to add
or change. 





Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-28 21:03:10 +00:00
Grindv1k
38feddb878 Add system sets and run criteria example (#1909)
If accepted, fixes #1694 .

I wanted to explore system sets and run criteria a bit, so made an example expanding a bit on the snippets shown in the 0.5 release post.

Shows a couple of system sets, uses system labels, run criterion, and a use of the interesting `RunCriterion::pipe` functionality.
2021-04-23 19:08:16 +00:00
François
e3fb23d4d3 add documentation on LogPlugin and more log usage (#1973)
Fixes #1895 

Changed most `println` to `info` in examples, some to `warn` when it was useful to differentiate from other more noisy logs.

Added doc on `LogPlugin`, how to configure it, and why (and how) you may need to disable it
2021-04-22 23:30:48 +00:00
Alice Cecile
e4e32598a9 Cargo fmt with unstable features (#1903)
Fresh version of #1670 off the latest main.

Mostly fixing documentation wrapping.
2021-04-21 23:19:34 +00:00
MinerSebas
458312236a Document setting "CARGO_MANIFEST_DIR" for asset root (#1950)
This was nowhere documented inside Bevy.
Should I also mention the use case of debugging a project?

Closes #810

Co-authored-by: MinerSebas <66798382+MinerSebas@users.noreply.github.com>
2021-04-19 22:16:23 +00:00
Mariusz Kryński
fa6d4dbd53 add render_to_texture example (#1927)
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-19 21:07:19 +00:00
Alister Lee
3d4b1b9ff2 Fix alien_cake_addict: cake should not be at height of player's location (#1954)
Just to avoid confusion to close readers of the example, this fix ensures cake is transformed to the height at the cake's cell, rather than the height at the player's cell.

Without this, cake may be floating or buried, depending on where the player is standing at time of spawning.

Love your work!
2021-04-19 20:45:41 +00:00
MinerSebas
20673dbe0e Doctest improvments (#1937) 2021-04-16 19:13:08 +00:00
Logan Magee
d508923eb7 Allow deriving SystemParam on private types (#1936)
Examples creating a public type to derive `SystemParam` on were updated
to create a private type where a public one is no longer needed.

Resolves #1869
2021-04-16 18:40:49 +00:00
Anselmo Sampietro
9b7ed18f72 Add animate shaders example (#1765)
This PR adds an example on how to animate a shader by passing the global `time.seconds_since_startup()` to a component, and accessing that component inside the shader.

Hopefully this is the current proper solution, please let me know if it should be solved in another way.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-15 19:49:31 +00:00
François
86f3308308 examples on how to tests systems (#1714)
well... those are examples on how to tests systems despawning entities, modifying components, accessing resources, spawning entities
2021-04-15 00:57:37 +00:00
follower
57e3d4f1c2 Fix the left/right movement direction in state example. (#1879)
Direction of movement was reversed, previously.

(i.e. Left arrow key moved sprite to the right; Right arrow key moved sprite to the left.)

This PR changes the code to now be consistent with, for example, the breakout example: 81b53d15d4/examples/game/breakout.rs (L184-L190)

i.e. AFAICT it's not an issue with the keycode being different/wrong.
2021-04-14 23:39:56 +00:00
Yoh Deadfall
8aa22ba477 Removed frame rate updates from fixed step example (#1850)
Fixes #1751.

Output before:

```
...
update: 0.016478100000000495
update: 0.01955749999999945
fixed_update: 2.0052284
  overstep_percentage: 0.00946374999999966
update: 0.013902800000000326
update: 0.02283240000000042
...
```

Output after:

```
...
fixed_update: 2.0053731
  overstep_percentage: 0.0031439500000001175
fixed_update: 1.9976363
  overstep_percentage: 0.0019621000000002997
fixed_update: 2.0069121999999995
  overstep_percentage: 0.005418200000000262
...
```
2021-04-14 22:38:04 +00:00
Aaron Winter
01142a137e Many Sprites Example Fix (#1897)
This example is supposed to use frustum culling, but doesn't. :P

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-13 20:18:56 +00:00
François
dae8357057 markdown lint on CHANGELOG.md and examples/READE.md (#1906)
new lints after #1783, fixes current CI break
2021-04-13 17:18:47 +00:00
Carter Anderson
5bccb67aa3 Remove unused material (#1898)
This doesn't do anything and complicates the example.
2021-04-13 02:39:50 +00:00
Jonas Matser
5c4f3554f9 Rename Light => PointLight and remove unused properties (#1778)
After an inquiry on Reddit about support for Directional Lights and the unused properties on Light, I wanted to clean it up, to hopefully make it ever so slightly more clear for anyone wanting to add additional light types.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-13 02:21:24 +00:00
Alessandro Re
6ce57c85d6 Example on how to draw using custom mesh and shader (#1565)
I was looking into "lower level" rendering and I saw no example on how to do that. Yet, I think it's something relevant to show, so I set up a simple example on how to do that. I hope it's welcome.

I'm not confident about the code and a review is definitely nice to have, especially because there are a few things that are not great.
Specifically, I think it would be nice to see how to render with a completely custom set of attributes (position and color, in this case), but I couldn't manage to get it working without normals and uv.

It makes sense if bevy Meshes need these two attributes, but I'm not sure about it.

Co-authored-by: Alessandro Re <ale@ale-re.net>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-12 19:47:12 +00:00
Mike
9186c4c8d2 Change breakout to use fixed timestamp (#1541)
This PR fixes https://github.com/bevyengine/bevy/issues/1240, where the ball is escaping the playing field at low framerates.  I did this by moving the movement and physics system into a Fixed Timestep system set and changing the movement steps to a constant.  So we lose the example use of delta_time for changing position, but gain a use of FixedTimestep.

If this is accepted https://github.com/bevyengine/bevy-website/pull/102 will need to be updated to match.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-04-12 19:29:08 +00:00
Grindv1k
9ac9088933 Remove leftover pbr_textures example (#1845)
`examples/3d/pbr_textures.rs` was missing in both `Cargo.toml` and in the examples
`README.md`.
2021-04-08 17:42:15 +00:00
Jonas Matser
9a78addff0 Add PBR textures (#1632)
This PR adds normal maps on top of PBR #1554. Once that PR lands, the changes should look simpler.

Edit: Turned out to be so little extra work, I added metallic/roughness texture too. And occlusion and emissive.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-03-26 21:00:34 +00:00
TheRawMeatball
78edec2e45 Change State::*_next to *_replace, add proper next (#1676)
In the current impl, next clears out the entire stack and replaces it with a new state. This PR moves this functionality into a replace method, and changes the behavior of next to only change the top state.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-03-25 03:28:40 +00:00
Aaron Winter
621cba4864 Example for 2D Frustum Culling (#1503)
This adds a new project for showing off Frustum Culling.
(Master runs this at sub 1 FPS while with the frustum culling it runs at 144 FPS on my system)

Short clip of the project running:
https://streamable.com/vvzh2u
2021-03-25 01:46:22 +00:00
Alexander Sepity
d3e020a1e7 System sets and run criteria v2 (#1675)
I'm opening this prematurely; consider this an RFC that predates RFCs and therefore not super-RFC-like.

This PR does two "big" things: decouple run criteria from system sets, reimagine system sets as weapons of mass system description.

### What it lets us do:

* Reuse run criteria within a stage.
* Pipe output of one run criteria as input to another.
* Assign labels, dependencies, run criteria, and ambiguity sets to many systems at the same time.

### Things already done:
* Decoupled run criteria from system sets.
* Mass system description superpowers to `SystemSet`.
* Implemented `RunCriteriaDescriptor`.
* Removed `VirtualSystemSet`.
* Centralized all run criteria of `SystemStage`.
* Extended system descriptors with per-system run criteria.
* `.before()` and `.after()` for run criteria.
* Explicit order between state driver and related run criteria. Fixes #1672.
* Opt-in run criteria deduplication; default behavior is to panic.
* Labels (not exposed) for state run criteria; state run criteria are deduplicated.

### API issues that need discussion:

* [`FixedTimestep::step(1.0).label("my label")`](eaccf857cd/crates/bevy_ecs/src/schedule/run_criteria.rs (L120-L122)) and [`FixedTimestep::step(1.0).with_label("my label")`](eaccf857cd/crates/bevy_core/src/time/fixed_timestep.rs (L86-L89)) are both valid but do very different things.

---

I will try to maintain this post up-to-date as things change. Do check the diffs in "edited" thingy from time to time.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-03-24 20:11:55 +00:00
Rob Parrett
1c573de4f9 Fix panic in multiple_windows example (#1737)
Fixes #1736

There seemed to be an obvious transcription error where `setup_pipeline` was being called during `on_update` of `AppState::CreateWindow` instead of `AppState::Setup`.

However, the example still panicked after fixing that.

I'm not sure if there's some intended or unintended change in event processing during state transitions or something, but this PR make the example work again.

Cleaned up an unused `Stage` label while I was in there.

Please feel free to close this in favor of another approach.
2021-03-24 00:39:54 +00:00
Nolan Darilek
9c252e904a Add LogPlugin, otherwise the ambiguity detector doesn't work. (#1740) 2021-03-23 20:29:28 +00:00
Carter Anderson
81b53d15d4 Make Commands and World apis consistent (#1703)
Resolves #1253 #1562

This makes the Commands apis consistent with World apis. This moves to a "type state" pattern (like World) where the "current entity" is stored in an `EntityCommands` builder.

In general this tends to cuts down on indentation and line count. It comes at the cost of needing to type `commands` more and adding more semicolons to terminate expressions.

I also added `spawn_bundle` to Commands because this is a common enough operation that I think its worth providing a shorthand.
2021-03-23 00:23:40 +00:00
François
94f45586ce alien-cake-addict example: ensure the cake doesn't spawn on the player (#1713)
fixes #1707 

In the game, it makes sense to never spawn the cake on the player.
2021-03-22 19:07:15 +00:00
Rob Parrett
3dc7b685ab Fix #1704 (#1705)
So I think that the underlying issue is actually a system order ambiguity thing between `spawn_bonus` and `rotate_bonus`, but I'm not confident enough about `run_criteria`, `FixedTimeStep`, etc. to sort that out.
2021-03-22 18:27:52 +00:00
Jonas Matser
cd8025d0a7 Remove remaining camerapos bindings (#1708)
Fixes #1706

@JeanMertz already solved it. I just ran all examples and tests.
2021-03-22 18:10:35 +00:00
Jonas Matser
45b2db7070 Rebase of existing PBR work (#1554)
This is a rebase of StarArawns PBR work from #261 with IngmarBitters work from #1160 cherry-picked on top.

I had to make a few minor changes to make some intermediate commits compile and the end result is not yet 100% what I expected, so there's a bit more work to do.

Co-authored-by: John Mitchell <toasterthegamer@gmail.com>
Co-authored-by: Ingmar Bitter <ingmar.bitter@gmail.com>
2021-03-20 03:22:33 +00:00
Carter Anderson
dd4a196329 Flexible camera bindings (#1689)
Alternative to #1203 and #1611

Camera bindings have historically been "hacked in". They were _required_ in all shaders and only supported a single Mat4. PBR (#1554) requires the CameraView matrix, but adding this using the "hacked" method forced users to either include all possible camera data in a single binding (#1203) or include all possible bindings (#1611).

This approach instead assigns each "active camera" its own RenderResourceBindings, which are populated by CameraNode. The PassNode then retrieves (and initializes) the relevant bind groups for all render pipelines used by visible entities. 

* Enables any number of camera bindings , including zero (with any set or binding number ... set 0 should still be used to avoid rebinds).
* Renames Camera binding to CameraViewProj
* Adds CameraView binding
2021-03-19 20:36:40 +00:00
Alice Cecile
6121e5f933 Reliable change detection (#1471)
# Problem Definition

The current change tracking (via flags for both components and resources) fails to detect changes made by systems that are scheduled to run earlier in the frame than they are.

This issue is discussed at length in [#68](https://github.com/bevyengine/bevy/issues/68) and [#54](https://github.com/bevyengine/bevy/issues/54).

This is very much a draft PR, and contributions are welcome and needed.

# Criteria
1. Each change is detected at least once, no matter the ordering.
2. Each change is detected at most once, no matter the ordering.
3. Changes should be detected the same frame that they are made.
4. Competitive ergonomics. Ideally does not require opting-in.
5. Low CPU overhead of computation.
6. Memory efficient. This must not increase over time, except where the number of entities / resources does.
7. Changes should not be lost for systems that don't run.
8. A frame needs to act as a pure function. Given the same set of entities / components it needs to produce the same end state without side-effects.

**Exact** change-tracking proposals satisfy criteria 1 and 2.
**Conservative** change-tracking proposals satisfy criteria 1 but not 2.
**Flaky** change tracking proposals satisfy criteria 2 but not 1.

# Code Base Navigation

There are three types of flags: 
- `Added`: A piece of data was added to an entity / `Resources`.
- `Mutated`: A piece of data was able to be modified, because its `DerefMut` was accessed
- `Changed`: The bitwise OR of `Added` and `Changed`

The special behavior of `ChangedRes`, with respect to the scheduler is being removed in [#1313](https://github.com/bevyengine/bevy/pull/1313) and does not need to be reproduced.

`ChangedRes` and friends can be found in "bevy_ecs/core/resources/resource_query.rs".

The `Flags` trait for Components can be found in "bevy_ecs/core/query.rs".

`ComponentFlags` are stored in "bevy_ecs/core/archetypes.rs", defined on line 446.

# Proposals

**Proposal 5 was selected for implementation.**

## Proposal 0: No Change Detection

The baseline, where computations are performed on everything regardless of whether it changed.

**Type:** Conservative

**Pros:**
- already implemented
- will never miss events
- no overhead

**Cons:**
- tons of repeated work
- doesn't allow users to avoid repeating work (or monitoring for other changes)

## Proposal 1: Earlier-This-Tick Change Detection

The current approach as of Bevy 0.4. Flags are set, and then flushed at the end of each frame.

**Type:** Flaky

**Pros:**
- already implemented
- simple to understand
- low memory overhead (2 bits per component)
- low time overhead (clear every flag once per frame)

**Cons:**
- misses systems based on ordering
- systems that don't run every frame miss changes
- duplicates detection when looping
- can lead to unresolvable circular dependencies

## Proposal 2: Two-Tick Change Detection

Flags persist for two frames, using a double-buffer system identical to that used in events.

A change is observed if it is found in either the current frame's list of changes or the previous frame's.

**Type:** Conservative

**Pros:**
- easy to understand
- easy to implement
- low memory overhead (4 bits per component)
- low time overhead (bit mask and shift every flag once per frame)

**Cons:**
- can result in a great deal of duplicated work
- systems that don't run every frame miss changes
- duplicates detection when looping

## Proposal 3: Last-Tick Change Detection

Flags persist for two frames, using a double-buffer system identical to that used in events.

A change is observed if it is found in the previous frame's list of changes.

**Type:** Exact

**Pros:**
- exact
- easy to understand
- easy to implement
- low memory overhead (4 bits per component)
- low time overhead (bit mask and shift every flag once per frame)

**Cons:**
- change detection is always delayed, possibly causing painful chained delays
- systems that don't run every frame miss changes
- duplicates detection when looping

## Proposal 4: Flag-Doubling Change Detection

Combine Proposal 2 and Proposal 3. Differentiate between `JustChanged` (current behavior) and `Changed` (Proposal 3).

Pack this data into the flags according to [this implementation proposal](https://github.com/bevyengine/bevy/issues/68#issuecomment-769174804).

**Type:** Flaky + Exact

**Pros:**
- allows users to acc
- easy to implement
- low memory overhead (4 bits per component)
- low time overhead (bit mask and shift every flag once per frame)

**Cons:**
- users must specify the type of change detection required
- still quite fragile to system ordering effects when using the flaky `JustChanged` form
- cannot get immediate + exact results
- systems that don't run every frame miss changes
- duplicates detection when looping

## [SELECTED] Proposal 5: Generation-Counter Change Detection

A global counter is increased after each system is run. Each component saves the time of last mutation, and each system saves the time of last execution. Mutation is detected when the component's counter is greater than the system's counter. Discussed [here](https://github.com/bevyengine/bevy/issues/68#issuecomment-769174804). How to handle addition detection is unsolved; the current proposal is to use the highest bit of the counter as in proposal 1.

**Type:** Exact (for mutations), flaky (for additions)

**Pros:**
- low time overhead (set component counter on access, set system counter after execution)
- robust to systems that don't run every frame
- robust to systems that loop

**Cons:**
- moderately complex implementation
- must be modified as systems are inserted dynamically
- medium memory overhead (4 bytes per component + system)
- unsolved addition detection

## Proposal 6: System-Data Change Detection

For each system, track which system's changes it has seen. This approach is only worth fully designing and implementing if Proposal 5 fails in some way.  

**Type:** Exact

**Pros:**
- exact
- conceptually simple

**Cons:**
- requires storing data on each system
- implementation is complex
- must be modified as systems are inserted dynamically

## Proposal 7: Total-Order Change Detection

Discussed [here](https://github.com/bevyengine/bevy/issues/68#issuecomment-754326523). This proposal is somewhat complicated by the new scheduler, but I believe it should still be conceptually feasible. This approach is only worth fully designing and implementing if Proposal 5 fails in some way.  

**Type:** Exact

**Pros:**
- exact
- efficient data storage relative to other exact proposals

**Cons:**
- requires access to the scheduler
- complex implementation and difficulty grokking
- must be modified as systems are inserted dynamically

# Tests

- We will need to verify properties 1, 2, 3, 7 and 8. Priority: 1 > 2 = 3 > 8 > 7
- Ideally we can use identical user-facing syntax for all proposals, allowing us to re-use the same syntax for each.
- When writing tests, we need to carefully specify order using explicit dependencies.
- These tests will need to be duplicated for both components and resources.
- We need to be sure to handle cases where ambiguous system orders exist.

`changing_system` is always the system that makes the changes, and `detecting_system` always detects the changes.

The component / resource changed will be simple boolean wrapper structs.

## Basic Added / Mutated / Changed

2 x 3 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs before `detecting_system`
- verify at the end of tick 2

## At Least Once

2 x 3 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs after `detecting_system`
- verify at the end of tick 2

## At Most Once

2 x 3 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs once before `detecting_system`
- increment a counter based on the number of changes detected
- verify at the end of tick 2

## Fast Detection
2 x 3 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs before `detecting_system`
- verify at the end of tick 1

## Ambiguous System Ordering Robustness
2 x 3 x 2 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs [before/after] `detecting_system` in tick 1
- `changing_system` runs [after/before] `detecting_system` in tick 2

## System Pausing
2 x 3 design:
- Resources vs. Components
- Added vs. Changed vs. Mutated
- `changing_system` runs in tick 1, then is disabled by run criteria
- `detecting_system` is disabled by run criteria until it is run once during tick 3
- verify at the end of tick 3

## Addition Causes Mutation

2 design:
- Resources vs. Components
- `adding_system_1` adds a component / resource
- `adding system_2` adds the same component / resource
- verify the `Mutated` flag at the end of the tick
- verify the `Added` flag at the end of the tick

First check tests for: https://github.com/bevyengine/bevy/issues/333
Second check tests for: https://github.com/bevyengine/bevy/issues/1443

## Changes Made By Commands

- `adding_system` runs in Update in tick 1, and sends a command to add a component 
- `detecting_system` runs in Update in tick 1 and 2, after `adding_system`
- We can't detect the changes in tick 1, since they haven't been processed yet
- If we were to track these changes as being emitted by `adding_system`, we can't detect the changes in tick 2 either, since `detecting_system` has already run once after `adding_system` :( 

# Benchmarks

See: [general advice](https://github.com/bevyengine/bevy/blob/master/docs/profiling.md), [Criterion crate](https://github.com/bheisler/criterion.rs)

There are several critical parameters to vary: 
1. entity count (1 to 10^9)
2. fraction of entities that are changed (0% to 100%)
3. cost to perform work on changed entities, i.e. workload (1 ns to 1s)

1 and 2 should be varied between benchmark runs. 3 can be added on computationally.

We want to measure:
- memory cost
- run time

We should collect these measurements across several frames (100?) to reduce bootup effects and accurately measure the mean, variance and drift.

Entity-component change detection is much more important to benchmark than resource change detection, due to the orders of magnitude higher number of pieces of data.

No change detection at all should be included in benchmarks as a second control for cases where missing changes is unacceptable.

## Graphs
1. y: performance, x: log_10(entity count), color: proposal, facet: performance metric. Set cost to perform work to 0. 
2. y: run time, x: cost to perform work, color: proposal, facet: fraction changed. Set number of entities to 10^6
3. y: memory, x: frames, color: proposal

# Conclusions
1. Is the theoretical categorization of the proposals correct according to our tests?
2. How does the performance of the proposals compare without any load?
3. How does the performance of the proposals compare with realistic loads?
4. At what workload does more exact change tracking become worth the (presumably) higher overhead?
5. When does adding change-detection to save on work become worthwhile?
6. Is there enough divergence in performance between the best solutions in each class to ship more than one change-tracking solution?

# Implementation Plan

1. Write a test suite.
2. Verify that tests fail for existing approach.
3. Write a benchmark suite.
4. Get performance numbers for existing approach.
5. Implement, test and benchmark various solutions using a Git branch per proposal.
6. Create a draft PR with all solutions and present results to team.
7. Select a solution and replace existing change detection.

Co-authored-by: Brice DAVIER <bricedavier@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-03-19 17:53:26 +00:00
François
bcd5318247 color spaces and representation (#1572)
`Color` can now be from different color spaces or representation:
- sRGB
- linear RGB
- HSL

This fixes #1193 by allowing the creation of const colors of all types, and writing it to the linear RGB color space for rendering.

I went with an enum after trying with two different types (`Color` and `LinearColor`) to be able to use the different variants in all place where a `Color` is expected.

I also added the HLS representation because:
- I like it
- it's useful for some case, see example `contributors`: I can just change the saturation and lightness while keeping the hue of the color
- I think adding another variant not using `red`, `green`, `blue` makes it clearer there are differences

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-03-17 23:59:51 +00:00
TheRawMeatball
284889c64b Redo State architecture (#1424)
An alternative to StateStages that uses SystemSets. Also includes pop and push operations since this was originally developed for my personal project which needed them.
2021-03-15 22:12:04 +00:00