Commit Graph

4 Commits

Author SHA1 Message Date
robtfm
6f2a5cb862
Bind group entries (#9694)
# Objective

Simplify bind group creation code. alternative to (and based on) #9476

## Solution

- Add a `BindGroupEntries` struct that can transparently be used where
`&[BindGroupEntry<'b>]` is required in BindGroupDescriptors.

Allows constructing the descriptor's entries as:
```rust
render_device.create_bind_group(
    "my_bind_group",
    &my_layout,
    &BindGroupEntries::with_indexes((
        (2, &my_sampler),
        (3, my_uniform),
    )),
);
```

instead of

```rust
render_device.create_bind_group(
    "my_bind_group",
    &my_layout,
    &[
        BindGroupEntry {
            binding: 2,
            resource: BindingResource::Sampler(&my_sampler),
        },
        BindGroupEntry {
            binding: 3,
            resource: my_uniform,
        },
    ],
);
```

or

```rust
render_device.create_bind_group(
    "my_bind_group",
    &my_layout,
    &BindGroupEntries::sequential((&my_sampler, my_uniform)),
);
```

instead of

```rust
render_device.create_bind_group(
    "my_bind_group",
    &my_layout,
    &[
        BindGroupEntry {
            binding: 0,
            resource: BindingResource::Sampler(&my_sampler),
        },
        BindGroupEntry {
            binding: 1,
            resource: my_uniform,
        },
    ],
);
```

the structs has no user facing macros, is tuple-type-based so stack
allocated, and has no noticeable impact on compile time.

- Also adds a `DynamicBindGroupEntries` struct with a similar api that
uses a `Vec` under the hood and allows extending the entries.
- Modifies `RenderDevice::create_bind_group` to take separate arguments
`label`, `layout` and `entries` instead of a `BindGroupDescriptor`
struct. The struct can't be stored due to the internal references, and
with only 3 members arguably does not add enough context to justify
itself.
- Modify the codebase to use the new api and the `BindGroupEntries` /
`DynamicBindGroupEntries` structs where appropriate (whenever the
entries slice contains more than 1 member).

## Migration Guide

- Calls to `RenderDevice::create_bind_group({BindGroupDescriptor {
label, layout, entries })` must be amended to
`RenderDevice::create_bind_group(label, layout, entries)`.
- If `label`s have been specified as `"bind_group_name".into()`, they
need to change to just `"bind_group_name"`. `Some("bind_group_name")`
and `None` will still work, but `Some("bind_group_name")` can optionally
be simplified to just `"bind_group_name"`.

---------

Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
2023-10-21 15:39:22 +00:00
Marco Buono
9b80205acb
Variable MeshPipeline View Bind Group Layout (#10156)
# Objective

This PR aims to make it so that we don't accidentally go over
`MAX_TEXTURE_IMAGE_UNITS` (in WebGL) or
`maxSampledTexturesPerShaderStage` (in WebGPU), giving us some extra
leeway to add more view bind group textures.

(This PR is extracted from—and unblocks—#8015)

## Solution

- We replace the existing `view_layout` and `view_layout_multisampled`
pair with an array of 32 bind group layouts, generated ahead of time;
- For now, these layouts cover all the possible combinations of:
`multisampled`, `depth_prepass`, `normal_prepass`,
`motion_vector_prepass` and `deferred_prepass`:
- In the future, as @JMS55 pointed out, we can likely take out
`motion_vector_prepass` and `deferred_prepass`, as these are not really
needed for the mesh pipeline and can use separate pipelines. This would
bring the possible combinations down to 8;
- We can also add more "optional" textures as they become needed,
allowing the engine to scale to a wider variety of use cases in lower
end/web environments (e.g. some apps might just want normal and depth
prepasses, others might only want light probes), while still keeping a
high ceiling for high end native environments where more textures are
supported.
- While preallocating bind group layouts is relatively cheap, the number
of combinations grows exponentially, so we should likely limit ourselves
to something like at most 256–1024 total layouts until we find a better
solution (like generating them lazily)
- To make this mechanism a little bit more explicit/discoverable, so
that compatibility with WebGPU/WebGL is not broken by accident, we add a
`MESH_PIPELINE_VIEW_LAYOUT_SAFE_MAX_TEXTURES` const and warn whenever
the number of textures in the layout crosses it.
- The warning is gated by `#[cfg(debug_assertions)]` and not issued in
release builds;
- We're counting the actual textures in the bind group layout instead of
using some roundabout metric so it should be accurate;
- Right now `MESH_PIPELINE_VIEW_LAYOUT_SAFE_MAX_TEXTURES` is set to 10
in order to leave 6 textures free for other groups;
- Currently there's no combination that would cause us to go over the
limit, but that will change once #8015 lands.

---

## Changelog

- `MeshPipeline` view bind group layouts now vary based on the current
multisampling and prepass states, saving a couple of texture binding
entries when prepasses are not in use.

## Migration Guide

- `MeshPipeline::view_layout` and
`MeshPipeline::view_layout_multisampled` have been replaced with a
private array to accomodate for variable view bind group layouts. To
obtain a view bind group layout for the current pipeline state, use the
new `MeshPipeline::get_view_layout()` or
`MeshPipeline::get_view_layout_from_key()` methods.
2023-10-21 11:19:44 +00:00
Marco Buono
5733d2403e
*_PREPASS Shader Def Cleanup (#10136)
# Objective

- This PR aims to make the various `*_PREPASS` shader defs we have
(`NORMAL_PREPASS`, `DEPTH_PREPASS`, `MOTION_VECTORS_PREPASS` AND
`DEFERRED_PREPASS`) easier to use and understand:
- So that their meaning is now consistent across all contexts; (“prepass
X is enabled for the current view”)
  - So that they're also consistently set across all contexts.
- It also aims to enable us to (with a follow up PR) to conditionally
gate the `BindGroupEntry` and `BindGroupLayoutEntry` items associated
with these prepasses, saving us up to 4 texture slots in WebGL
(currently globally limited to 16 per shader, regardless of bind groups)

## Solution

- We now consistently set these from `PrepassPipeline`, the
`MeshPipeline` and the `DeferredLightingPipeline`, we also set their
`MeshPipelineKey`s;
- We introduce `PREPASS_PIPELINE`, `MESH_PIPELINE` and
`DEFERRED_LIGHTING_PIPELINE` that can be used to detect where the code
is running, without overloading the meanings of the prepass shader defs;
- We also gate the WGSL functions in `bevy_pbr::prepass_utils` with
`#ifdef`s for their respective shader defs, so that shader code can
provide a fallback whenever they're not available.
- This allows us to conditionally include the bindings for these prepass
textures (My next PR, which will hopefully unblock #8015)
- @robtfm mentioned [these were being used to prevent accessing the same
binding as read/write in the
prepass](https://discord.com/channels/691052431525675048/743663924229963868/1163270458393759814),
however even after reversing the `#ifndef`s I had no issues running the
code, so perhaps the compiler is already smart enough even without tree
shaking to know they're not being used, thanks to `#ifdef
PREPASS_PIPELINE`?

## Comparison

### Before

| Shader Def | `PrepassPipeline` | `MeshPipeline` |
`DeferredLightingPipeline` |
| ------------------------ | ----------------- | -------------- |
-------------------------- |
| `NORMAL_PREPASS` | Yes | No | No |
| `DEPTH_PREPASS` | Yes | No | No |
| `MOTION_VECTORS_PREPASS` | Yes | No | No |
| `DEFERRED_PREPASS` | Yes | No | No |

| View Key | `PrepassPipeline` | `MeshPipeline` |
`DeferredLightingPipeline` |
| ------------------------ | ----------------- | -------------- |
-------------------------- |
| `NORMAL_PREPASS` | Yes | Yes | No |
| `DEPTH_PREPASS` | Yes | No | No |
| `MOTION_VECTORS_PREPASS` | Yes | No | No |
| `DEFERRED_PREPASS` | Yes | Yes\* | No |

\* Accidentally was being set twice, once with only
`deferred_prepass.is_some()` as a condition,
and once with `deferred_p repass.is_some() && !forward` as a condition.

### After

| Shader Def | `PrepassPipeline` | `MeshPipeline` |
`DeferredLightingPipeline` |
| ---------------------------- | ----------------- | --------------- |
-------------------------- |
| `NORMAL_PREPASS` | Yes | Yes | Yes |
| `DEPTH_PREPASS` | Yes | Yes | Yes |
| `MOTION_VECTORS_PREPASS` | Yes | Yes | Yes |
| `DEFERRED_PREPASS` | Yes | Yes | Unconditionally |
| `PREPASS_PIPELINE` | Unconditionally | No | No |
| `MESH_PIPELINE` | No | Unconditionally | No |
| `DEFERRED_LIGHTING_PIPELINE` | No | No | Unconditionally |

| View Key | `PrepassPipeline` | `MeshPipeline` |
`DeferredLightingPipeline` |
| ------------------------ | ----------------- | -------------- |
-------------------------- |
| `NORMAL_PREPASS` | Yes | Yes | Yes |
| `DEPTH_PREPASS` | Yes | Yes | Yes |
| `MOTION_VECTORS_PREPASS` | Yes | Yes | Yes |
| `DEFERRED_PREPASS` | Yes | Yes | Unconditionally |

---

## Changelog

- Cleaned up WGSL `*_PREPASS` shader defs so they're now consistently
used everywhere;
- Introduced `PREPASS_PIPELINE`, `MESH_PIPELINE` and
`DEFERRED_LIGHTING_PIPELINE` WGSL shader defs for conditionally
compiling logic based the current pipeline;
- WGSL functions from `bevy_pbr::prepass_utils` are now guarded with
`#ifdef` based on the currently enabled prepasses;

## Migration Guide

- When using functions from `bevy_pbr::prepass_utils`
(`prepass_depth()`, `prepass_normal()`, `prepass_motion_vector()`) in
contexts where these prepasses might be disabled, you should now wrap
your calls with the appropriate `#ifdef` guards, (`#ifdef
DEPTH_PREPASS`, `#ifdef NORMAL_PREPASS`, `#ifdef MOTION_VECTOR_PREPASS`)
providing fallback logic where applicable.

---------

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
2023-10-17 00:16:21 +00:00
Griffin
a15d152635
Deferred Renderer (#9258)
# Objective

- Add a [Deferred
Renderer](https://en.wikipedia.org/wiki/Deferred_shading) to Bevy.
- This allows subsequent passes to access per pixel material information
before/during shading.
- Accessing this per pixel material information is needed for some
features, like GI. It also makes other features (ex. Decals) simpler to
implement and/or improves their capability. There are multiple
approaches to accomplishing this. The deferred shading approach works
well given the limitations of WebGPU and WebGL2.

Motivation: [I'm working on a GI solution for
Bevy](https://youtu.be/eH1AkL-mwhI)

# Solution
- The deferred renderer is implemented with a prepass and a deferred
lighting pass.
- The prepass renders opaque objects into the Gbuffer attachment
(`Rgba32Uint`). The PBR shader generates a `PbrInput` in mostly the same
way as the forward implementation and then [packs it into the
Gbuffer](ec1465559f/crates/bevy_pbr/src/render/pbr.wgsl (L168)).
- The deferred lighting pass unpacks the `PbrInput` and [feeds it into
the pbr()
function](ec1465559f/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl (L65)),
then outputs the shaded color data.

- There is now a resource
[DefaultOpaqueRendererMethod](ec1465559f/crates/bevy_pbr/src/material.rs (L599))
that can be used to set the default render method for opaque materials.
If materials return `None` from
[opaque_render_method()](ec1465559f/crates/bevy_pbr/src/material.rs (L131))
the `DefaultOpaqueRendererMethod` will be used. Otherwise, custom
materials can also explicitly choose to only support Deferred or Forward
by returning the respective
[OpaqueRendererMethod](ec1465559f/crates/bevy_pbr/src/material.rs (L603))

- Deferred materials can be used seamlessly along with both opaque and
transparent forward rendered materials in the same scene. The [deferred
rendering
example](https://github.com/DGriffin91/bevy/blob/deferred/examples/3d/deferred_rendering.rs)
does this.

- The deferred renderer does not support MSAA. If any deferred materials
are used, MSAA must be disabled. Both TAA and FXAA are supported.

- Deferred rendering supports WebGL2/WebGPU. 

## Custom deferred materials
- Custom materials can support both deferred and forward at the same
time. The
[StandardMaterial](ec1465559f/crates/bevy_pbr/src/render/pbr.wgsl (L166))
does this. So does [this
example](https://github.com/DGriffin91/bevy_glowy_orb_tutorial/blob/deferred/assets/shaders/glowy.wgsl#L56).
- Custom deferred materials that require PBR lighting can create a
`PbrInput`, write it to the deferred GBuffer and let it be rendered by
the `PBRDeferredLightingPlugin`.
- Custom deferred materials that require custom lighting have two
options:
1. Use the base_color channel of the `PbrInput` combined with the
`STANDARD_MATERIAL_FLAGS_UNLIT_BIT` flag.
[Example.](https://github.com/DGriffin91/bevy_glowy_orb_tutorial/blob/deferred/assets/shaders/glowy.wgsl#L56)
(If the unlit bit is set, the base_color is stored as RGB9E5 for extra
precision)
2. A Custom Deferred Lighting pass can be created, either overriding the
default, or running in addition. The a depth buffer is used to limit
rendering to only the required fragments for each deferred lighting
pass. Materials can set their respective depth id via the
[deferred_lighting_pass_id](b79182d2a3/crates/bevy_pbr/src/prepass/prepass_io.wgsl (L95))
attachment. The custom deferred lighting pass plugin can then set [its
corresponding
depth](ec1465559f/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl (L37)).
Then with the lighting pass using
[CompareFunction::Equal](ec1465559f/crates/bevy_pbr/src/deferred/mod.rs (L335)),
only the fragments with a depth that equal the corresponding depth
written in the material will be rendered.

Custom deferred lighting plugins can also be created to render the
StandardMaterial. The default deferred lighting plugin can be bypassed
with `DefaultPlugins.set(PBRDeferredLightingPlugin { bypass: true })`

---------

Co-authored-by: nickrart <nickolas.g.russell@gmail.com>
2023-10-12 22:10:38 +00:00