Commit Graph

14 Commits

Author SHA1 Message Date
Nicky Fahey
831073105f
Add comment to custom vertex attribute example to make it easier to convert to 2D (#18603)
# Objective

- It's not clear what changes are needed to the shader to convert the
example to 2D.
- If you leave the shader unchanged you get a very confusing error (see
linked issue).
- Fixes #14077

## Solution

A separate example probably isn't needed as there is little difference
between 3D and 2D, but a note saying what changes are needed to the
shader would make it a lot easier.

Let me know if you think it is also worth adding some notes to the rust
file, but it is mostly trivial changes such as changing `Mesh3d` to
`Mesh2d`. I have left the original code in comments next to the changes
in the gist linked at the bottom if you wish to compare.

## Testing

- I just spent a long time working it out the hard way. This would have
made it a lot quicker.
- I have tested the 2D version of the shader with the changes explained
in the suggested comment and it works as expected.
- For testing purposes [here is a complete working 2D
example](https://gist.github.com/nickyfahey/647e2a2c45e695f24e288432b811dfc2).
(note that as per the original example the shader file needs to go in
'assets/shaders/')
2025-07-07 19:26:37 +00:00
charlotte 🌸
96dcbc5f8c
Ugrade to wgpu version 25.0 (#19563)
# Objective

Upgrade to `wgpu` version `25.0`.

Depends on https://github.com/bevyengine/naga_oil/pull/121

## Solution

### Problem

The biggest issue we face upgrading is the following requirement:
> To facilitate this change, there was an additional validation rule put
in place: if there is a binding array in a bind group, you may not use
dynamic offset buffers or uniform buffers in that bind group. This
requirement comes from vulkan rules on UpdateAfterBind descriptors.

This is a major difficulty for us, as there are a number of binding
arrays that are used in the view bind group. Note, this requirement does
not affect merely uniform buffors that use dynamic offset but the use of
*any* uniform in a bind group that also has a binding array.

### Attempted fixes

The easiest fix would be to change uniforms to be storage buffers
whenever binding arrays are in use:
```wgsl
#ifdef BINDING_ARRAYS_ARE_USED
@group(0) @binding(0) var<uniform> view: View;
@group(0) @binding(1) var<uniform> lights: types::Lights;
#else
@group(0) @binding(0) var<storage> view: array<View>;
@group(0) @binding(1) var<storage> lights: array<types::Lights>;
#endif
```

This requires passing the view index to the shader so that we know where
to index into the buffer:

```wgsl
struct PushConstants {
    view_index: u32,
}

var<push_constant> push_constants: PushConstants;
```

Using push constants is no problem because binding arrays are only
usable on native anyway.

However, this greatly complicates the ability to access `view` in
shaders. For example:
```wgsl
#ifdef BINDING_ARRAYS_ARE_USED
mesh_view_bindings::view.view_from_world[0].z
#else
mesh_view_bindings::view[mesh_view_bindings::view_index].view_from_world[0].z
#endif
```

Using this approach would work but would have the effect of polluting
our shaders with ifdef spam basically *everywhere*.

Why not use a function? Unfortunately, the following is not valid wgsl
as it returns a binding directly from a function in the uniform path.

```wgsl
fn get_view() -> View {
#if BINDING_ARRAYS_ARE_USED
    let view_index = push_constants.view_index;
    let view = views[view_index];
#endif
    return view;
}
```

This also poses problems for things like lights where we want to return
a ptr to the light data. Returning ptrs from wgsl functions isn't
allowed even if both bindings were buffers.

The next attempt was to simply use indexed buffers everywhere, in both
the binding array and non binding array path. This would be viable if
push constants were available everywhere to pass the view index, but
unfortunately they are not available on webgpu. This means either
passing the view index in a storage buffer (not ideal for such a small
amount of state) or using push constants sometimes and uniform buffers
only on webgpu. However, this kind of conditional layout infects
absolutely everything.

Even if we were to accept just using storage buffer for the view index,
there's also the additional problem that some dynamic offsets aren't
actually per-view but per-use of a setting on a camera, which would
require passing that uniform data on *every* camera regardless of
whether that rendering feature is being used, which is also gross.

As such, although it's gross, the simplest solution just to bump binding
arrays into `@group(1)` and all other bindings up one bind group. This
should still bring us under the device limit of 4 for most users.

### Next steps / looking towards the future

I'd like to avoid needing split our view bind group into multiple parts.
In the future, if `wgpu` were to add `@builtin(draw_index)`, we could
build a list of draw state in gpu processing and avoid the need for any
kind of state change at all (see
https://github.com/gfx-rs/wgpu/issues/6823). This would also provide
significantly more flexibility to handle things like offsets into other
arrays that may not be per-view.

### Testing

Tested a number of examples, there are probably more that are still
broken.

---------

Co-authored-by: François Mockers <mockersf@gmail.com>
Co-authored-by: Elabajaba <Elabajaba@users.noreply.github.com>
2025-06-26 19:41:47 +00:00
Ricky Taylor
9b9d3d81cb
Normalise matrix naming (#13489)
# Objective
- Fixes #10909
- Fixes #8492

## Solution
- Name all matrices `x_from_y`, for example `world_from_view`.

## Testing
- I've tested most of the 3D examples. The `lighting` example
particularly should hit a lot of the changes and appears to run fine.

---

## Changelog
- Renamed matrices across the engine to follow a `y_from_x` naming,
making the space conversion more obvious.

## Migration Guide
- `Frustum`'s `from_view_projection`, `from_view_projection_custom_far`
and `from_view_projection_no_far` were renamed to
`from_clip_from_world`, `from_clip_from_world_custom_far` and
`from_clip_from_world_no_far`.
- `ComputedCameraValues::projection_matrix` was renamed to
`clip_from_view`.
- `CameraProjection::get_projection_matrix` was renamed to
`get_clip_from_view` (this affects implementations on `Projection`,
`PerspectiveProjection` and `OrthographicProjection`).
- `ViewRangefinder3d::from_view_matrix` was renamed to
`from_world_from_view`.
- `PreviousViewData`'s members were renamed to `view_from_world` and
`clip_from_world`.
- `ExtractedView`'s `projection`, `transform` and `view_projection` were
renamed to `clip_from_view`, `world_from_view` and `clip_from_world`.
- `ViewUniform`'s `view_proj`, `unjittered_view_proj`,
`inverse_view_proj`, `view`, `inverse_view`, `projection` and
`inverse_projection` were renamed to `clip_from_world`,
`unjittered_clip_from_world`, `world_from_clip`, `world_from_view`,
`view_from_world`, `clip_from_view` and `view_from_clip`.
- `GpuDirectionalCascade::view_projection` was renamed to
`clip_from_world`.
- `MeshTransforms`' `transform` and `previous_transform` were renamed to
`world_from_local` and `previous_world_from_local`.
- `MeshUniform`'s `transform`, `previous_transform`,
`inverse_transpose_model_a` and `inverse_transpose_model_b` were renamed
to `world_from_local`, `previous_world_from_local`,
`local_from_world_transpose_a` and `local_from_world_transpose_b` (the
`Mesh` type in WGSL mirrors this, however `transform` and
`previous_transform` were named `model` and `previous_model`).
- `Mesh2dTransforms::transform` was renamed to `world_from_local`.
- `Mesh2dUniform`'s `transform`, `inverse_transpose_model_a` and
`inverse_transpose_model_b` were renamed to `world_from_local`,
`local_from_world_transpose_a` and `local_from_world_transpose_b` (the
`Mesh2d` type in WGSL mirrors this).
- In WGSL, in `bevy_pbr::mesh_functions`, `get_model_matrix` and
`get_previous_model_matrix` were renamed to `get_world_from_local` and
`get_previous_world_from_local`.
- In WGSL, `bevy_sprite::mesh2d_functions::get_model_matrix` was renamed
to `get_world_from_local`.
2024-06-03 16:56:53 +00:00
JMS55
4bf20e7d27
Swap material and mesh bind groups (#10485)
# Objective
- Materials should be a more frequent rebind then meshes (due to being
able to use a single vertex buffer, such as in #10164) and therefore
should be in a higher bind group.

---

## Changelog
- For 2d and 3d mesh/material setups (but not UI materials, or other
rendering setups such as gizmos, sprites, or text), mesh data is now in
bind group 1, and material data is now in bind group 2, which is swapped
from how they were before.

## Migration Guide
- Custom 2d and 3d mesh/material shaders should now use bind group 2
`@group(2) @binding(x)` for their bound resources, instead of bind group
1.
- Many internal pieces of rendering code have changed so that mesh data
is now in bind group 1, and material data is now in bind group 2.
Semi-custom rendering setups (that don't use the Material or Material2d
APIs) should adapt to these changes.
2023-11-28 22:26:22 +00:00
robtfm
61bad4eb57
update shader imports (#10180)
# Objective

- bump naga_oil to 0.10
- update shader imports to use rusty syntax

## Migration Guide

naga_oil 0.10 reworks the import mechanism to support more syntax to
make it more rusty, and test for item use before importing to determine
which imports are modules and which are items, which allows:

- use rust-style imports
```
#import bevy_pbr::{
    pbr_functions::{alpha_discard as discard, apply_pbr_lighting}, 
    mesh_bindings,
}
```

- import partial paths:
```
#import part::of::path
...
path::remainder::function();
```
which will call to `part::of::path::remainder::function`

- use fully qualified paths without importing:
```
// #import bevy_pbr::pbr_functions
bevy_pbr::pbr_functions::pbr()
```
- use imported items without qualifying
```
#import bevy_pbr::pbr_functions::pbr
// for backwards compatibility the old style is still supported:
// #import bevy_pbr::pbr_functions pbr
...
pbr()
```

- allows most imported items to end with `_` and numbers (naga_oil#30).
still doesn't allow struct members to end with `_` or numbers but it's
progress.

- the vast majority of existing shader code will work without changes,
but will emit "deprecated" warnings for old-style imports. these can be
suppressed with the `allow-deprecated` feature.

- partly breaks overrides (as far as i'm aware nobody uses these yet) -
now overrides will only be applied if the overriding module is added as
an additional import in the arguments to `Composer::make_naga_module` or
`Composer::add_composable_module`. this is necessary to support
determining whether imports are modules or items.
2023-10-21 11:51:58 +00:00
Nicola Papale
7163aabf29
Use a single line for of large binding lists (#9849)
# Objective

- When adding/removing bindings in large binding lists, git would
generate very difficult-to-read diffs

## Solution

- Move the `@group(X) @binding(Y)` into the same line as the binding
type declaration
2023-09-19 22:17:44 +00:00
Robert Swain
0a11af9375
Reduce the size of MeshUniform to improve performance (#9416)
# Objective

- Significantly reduce the size of MeshUniform by only including
necessary data.

## Solution

Local to world, model transforms are affine. This means they only need a
4x3 matrix to represent them.

`MeshUniform` stores the current, and previous model transforms, and the
inverse transpose of the current model transform, all as 4x4 matrices.
Instead we can store the current, and previous model transforms as 4x3
matrices, and we only need the upper-left 3x3 part of the inverse
transpose of the current model transform. This change allows us to
reduce the serialized MeshUniform size from 208 bytes to 144 bytes,
which is over a 30% saving in data to serialize, and VRAM bandwidth and
space.

## Benchmarks

On an M1 Max, running `many_cubes -- sphere`, main is in yellow, this PR
is in red:
<img width="1484" alt="Screenshot 2023-08-11 at 02 36 43"
src="https://github.com/bevyengine/bevy/assets/302146/7d99c7b3-f2bb-4004-a8d0-4c00f755cb0d">
A reduction in frame time of ~14%.

---

## Changelog

- Changed: Redefined `MeshUniform` to improve performance by using 4x3
affine transforms and reconstructing 4x4 matrices in the shader. Helper
functions were added to `bevy_pbr::mesh_functions` to unpack the data.
`affine_to_square` converts the packed 4x3 in 3x4 matrix data to a 4x4
matrix. `mat2x4_f32_to_mat3x3` converts the 3x3 in mat2x4 + f32 matrix
data back into a 3x3.

## Migration Guide

Shader code before:
```
var model = mesh[instance_index].model;
```

Shader code after:
```
#import bevy_pbr::mesh_functions affine_to_square

var model = affine_to_square(mesh[instance_index].model);
```
2023-08-15 06:00:23 +00:00
Robert Swain
c1a5428f8e
Work around naga/wgpu WGSL instance_index -> GLSL gl_InstanceID bug on WebGL2 (#9383)
naga and wgpu should polyfill WGSL instance_index functionality where it
is not available in GLSL. Until that is done, we can work around it in
bevy using a push constant which is converted to a uniform by naga and
wgpu.

# Objective

- Fixes #9375 

## Solution

- Use a push constant to pass in the base instance to the shader on
WebGL2 so that base instance + gl_InstanceID is used to correctly
represent the instance index.

## TODO

- [ ] Benchmark vs per-object dynamic offset MeshUniform as this will
now push a uniform value per-draw as well as update the dynamic offset
per-batch.
- [x] Test on DX12 AMD/NVIDIA to check that this PR does not regress any
problems that were observed there. (@Elabajaba @robtfm were testing that
last time - help appreciated. <3 )

---

## Changelog

- Added: `bevy_render::instance_index` shader import which includes a
workaround for the lack of a WGSL `instance_index` polyfill for WebGL2
in naga and wgpu for the time being. It uses a push_constant which gets
converted to a plain uniform by naga and wgpu.

## Migration Guide

Shader code before:

```
struct Vertex {
    @builtin(instance_index) instance_index: u32,
...
}

@vertex
fn vertex(vertex_no_morph: Vertex) -> VertexOutput {
...

    var model = mesh[vertex_no_morph.instance_index].model;
```

After:

```
#import bevy_render::instance_index

struct Vertex {
    @builtin(instance_index) instance_index: u32,
...
}

@vertex
fn vertex(vertex_no_morph: Vertex) -> VertexOutput {
...

    var model = mesh[bevy_render::instance_index::get_instance_index(vertex_no_morph.instance_index)].model;
```
2023-08-09 18:38:45 +00:00
Robert Swain
e6405bb7b4
Use GpuArrayBuffer for MeshUniform (#9254)
# Objective

- Reduce the number of rebindings to enable batching of draw commands

## Solution

- Use the new `GpuArrayBuffer` for `MeshUniform` data to store all
`MeshUniform` data in arrays within fewer bindings
- Sort opaque/alpha mask prepass, opaque/alpha mask main, and shadow
phases also by the batch per-object data binding dynamic offset to
improve performance on WebGL2.

---

## Changelog

- Changed: Per-object `MeshUniform` data is now managed by
`GpuArrayBuffer` as arrays in buffers that need to be indexed into.

## Migration Guide

Accessing the `model` member of an individual mesh object's shader
`Mesh` struct the old way where each `MeshUniform` was stored at its own
dynamic offset:
```rust
struct Vertex {
    @location(0) position: vec3<f32>,
};

fn vertex(vertex: Vertex) -> VertexOutput {
    var out: VertexOutput;
    out.clip_position = mesh_position_local_to_clip(
        mesh.model,
        vec4<f32>(vertex.position, 1.0)
    );
    return out;
}
```

The new way where one needs to index into the array of `Mesh`es for the
batch:
```rust
struct Vertex {
    @builtin(instance_index) instance_index: u32,
    @location(0) position: vec3<f32>,
};

fn vertex(vertex: Vertex) -> VertexOutput {
    var out: VertexOutput;
    out.clip_position = mesh_position_local_to_clip(
        mesh[vertex.instance_index].model,
        vec4<f32>(vertex.position, 1.0)
    );
    return out;
}
```
Note that using the instance_index is the default way to pass the
per-object index into the shader, but if you wish to do custom rendering
approaches you can pass it in however you like.

---------

Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com>
Co-authored-by: Elabajaba <Elabajaba@users.noreply.github.com>
2023-07-30 13:17:08 +00:00
robtfm
10f5c92068
improve shader import model (#5703)
# Objective

operate on naga IR directly to improve handling of shader modules.
- give codespan reporting into imported modules
- allow glsl to be used from wgsl and vice-versa

the ultimate objective is to make it possible to 
- provide user hooks for core shader functions (to modify light
behaviour within the standard pbr pipeline, for example)
- make automatic binding slot allocation possible

but ... since this is already big, adds some value and (i think) is at
feature parity with the existing code, i wanted to push this now.

## Solution

i made a crate called naga_oil (https://github.com/robtfm/naga_oil -
unpublished for now, could be part of bevy) which manages modules by
- building each module independantly to naga IR
- creating "header" files for each supported language, which are used to
build dependent modules/shaders
- make final shaders by combining the shader IR with the IR for imported
modules

then integrated this into bevy, replacing some of the existing shader
processing stuff. also reworked examples to reflect this.

## Migration Guide

shaders that don't use `#import` directives should work without changes.

the most notable user-facing difference is that imported
functions/variables/etc need to be qualified at point of use, and
there's no "leakage" of visible stuff into your shader scope from the
imports of your imports, so if you used things imported by your imports,
you now need to import them directly and qualify them.

the current strategy of including/'spreading' `mesh_vertex_output`
directly into a struct doesn't work any more, so these need to be
modified as per the examples (e.g. color_material.wgsl, or many others).
mesh data is assumed to be in bindgroup 2 by default, if mesh data is
bound into bindgroup 1 instead then the shader def `MESH_BINDGROUP_1`
needs to be added to the pipeline shader_defs.
2023-06-27 00:29:22 +00:00
François
814f8d1635 update wgpu to 0.13 (#5168)
# Objective

- Update wgpu to 0.13
- ~~Wait, is wgpu 0.13 released? No, but I had most of the changes already ready since playing with webgpu~~ well it has been released now
- Also update parking_lot to 0.12 and naga to 0.9

## Solution

- Update syntax for wgsl shaders https://github.com/gfx-rs/wgpu/blob/master/CHANGELOG.md#wgsl-syntax
- Add a few options, remove some references: https://github.com/gfx-rs/wgpu/blob/master/CHANGELOG.md#other-breaking-changes
- fragment inputs should now exactly match vertex outputs for locations, so I added exports for those to be able to reuse them https://github.com/gfx-rs/wgpu/pull/2704
2022-07-14 21:17:16 +00:00
Robert Swain
b333386271 Add reusable shader functions for transforming position/normal/tangent (#4901)
# Objective

- Add reusable shader functions for transforming positions / normals / tangents between local and world / clip space for 2D and 3D so that they are done in a simple and correct way
- The next step in #3969 so check there for more details.

## Solution

- Add `bevy_pbr::mesh_functions` and `bevy_sprite::mesh2d_functions` shader imports
  - These contain `mesh_` and `mesh2d_` versions of the following functions:
    - `mesh_position_local_to_world`
    - `mesh_position_world_to_clip`
    - `mesh_position_local_to_clip`
    - `mesh_normal_local_to_world`
    - `mesh_tangent_local_to_world`
- Use them everywhere where it is appropriate
  - Notably not in the sprite and UI shaders where `mesh2d_position_world_to_clip` could have been used, but including all the functions depends on the mesh binding so I chose to not use the function there
- NOTE: The `mesh_` and `mesh2d_` functions are currently identical. However, if I had defined only `bevy_pbr::mesh_functions` and used that in bevy_sprite, then bevy_sprite would have a runtime dependency on bevy_pbr, which seems undesirable. I also expect that when we have a proper 2D rendering API, these functions will diverge between 2D and 3D.

---

## Changelog

- Added: `bevy_pbr::mesh_functions` and `bevy_sprite::mesh2d_functions` shader imports containing `mesh_` and `mesh2d_` versions of the following functions:
  - `mesh_position_local_to_world`
  - `mesh_position_world_to_clip`
  - `mesh_position_local_to_clip`
  - `mesh_normal_local_to_world`
  - `mesh_tangent_local_to_world`

## Migration Guide

- The `skin_tangents` function from the `bevy_pbr::skinning` shader import has been replaced with the `mesh_tangent_local_to_world` function from the `bevy_pbr::mesh_functions` shader import
2022-06-14 00:32:33 +00:00
Robert Swain
cc4062ec43 Split mesh shader files (#4867)
# Objective

- Split PBR and 2D mesh shaders into types and bindings to prepare the shaders to be more reusable.
- See #3969 for details. I'm doing this in multiple steps to make review easier.

---

## Changelog

- Changed: 2D and PBR mesh shaders are now split into types and bindings, the following shader imports are available: `bevy_pbr::mesh_view_types`, `bevy_pbr::mesh_view_bindings`, `bevy_pbr::mesh_types`, `bevy_pbr::mesh_bindings`, `bevy_sprite::mesh2d_view_types`, `bevy_sprite::mesh2d_view_bindings`, `bevy_sprite::mesh2d_types`, `bevy_sprite::mesh2d_bindings`

## Migration Guide

- In shaders for 3D meshes:
  - `#import bevy_pbr::mesh_view_bind_group` -> `#import bevy_pbr::mesh_view_bindings`
  - `#import bevy_pbr::mesh_struct` -> `#import bevy_pbr::mesh_types`
    - NOTE: If you are using the mesh bind group at bind group index 2, you can remove those binding statements in your shader and just use `#import bevy_pbr::mesh_bindings` which itself imports the mesh types needed for the bindings.
- In shaders for 2D meshes:
  - `#import bevy_sprite::mesh2d_view_bind_group` -> `#import bevy_sprite::mesh2d_view_bindings`
  - `#import bevy_sprite::mesh2d_struct` -> `#import bevy_sprite::mesh2d_types`
    - NOTE: If you are using the mesh2d bind group at bind group index 2, you can remove those binding statements in your shader and just use `#import bevy_sprite::mesh2d_bindings` which itself imports the mesh2d types needed for the bindings.
2022-05-31 23:23:25 +00:00
Carter Anderson
e369a8ad51 Mesh vertex buffer layouts (#3959)
This PR makes a number of changes to how meshes and vertex attributes are handled, which the goal of enabling easy and flexible custom vertex attributes:
* Reworks the `Mesh` type to use the newly added `VertexAttribute` internally
  * `VertexAttribute` defines the name, a unique `VertexAttributeId`, and a `VertexFormat`
  *  `VertexAttributeId` is used to produce consistent sort orders for vertex buffer generation, replacing the more expensive and often surprising "name based sorting"  
  * Meshes can be used to generate a `MeshVertexBufferLayout`, which defines the layout of the gpu buffer produced by the mesh. `MeshVertexBufferLayouts` can then be used to generate actual `VertexBufferLayouts` according to the requirements of a specific pipeline. This decoupling of "mesh layout" vs "pipeline vertex buffer layout" is what enables custom attributes. We don't need to standardize _mesh layouts_ or contort meshes to meet the needs of a specific pipeline. As long as the mesh has what the pipeline needs, it will work transparently. 
* Mesh-based pipelines now specialize on `&MeshVertexBufferLayout` via the new `SpecializedMeshPipeline` trait (which behaves like `SpecializedPipeline`, but adds `&MeshVertexBufferLayout`). The integrity of the pipeline cache is maintained because the `MeshVertexBufferLayout` is treated as part of the key (which is fully abstracted from implementers of the trait ... no need to add any additional info to the specialization key).    
* Hashing `MeshVertexBufferLayout` is too expensive to do for every entity, every frame. To make this scalable, I added a generalized "pre-hashing" solution to `bevy_utils`: `Hashed<T>` keys and `PreHashMap<K, V>` (which uses `Hashed<T>` internally) . Why didn't I just do the quick and dirty in-place "pre-compute hash and use that u64 as a key in a hashmap" that we've done in the past? Because its wrong! Hashes by themselves aren't enough because two different values can produce the same hash. Re-hashing a hash is even worse! I decided to build a generalized solution because this pattern has come up in the past and we've chosen to do the wrong thing. Now we can do the right thing! This did unfortunately require pulling in `hashbrown` and using that in `bevy_utils`, because avoiding re-hashes requires the `raw_entry_mut` api, which isn't stabilized yet (and may never be ... `entry_ref` has favor now, but also isn't available yet). If std's HashMap ever provides the tools we need, we can move back to that. Note that adding `hashbrown` doesn't increase our dependency count because it was already in our tree. I will probably break these changes out into their own PR.
* Specializing on `MeshVertexBufferLayout` has one non-obvious behavior: it can produce identical pipelines for two different MeshVertexBufferLayouts. To optimize the number of active pipelines / reduce re-binds while drawing, I de-duplicate pipelines post-specialization using the final `VertexBufferLayout` as the key.  For example, consider a pipeline that needs the layout `(position, normal)` and is specialized using two meshes: `(position, normal, uv)` and `(position, normal, other_vec2)`. If both of these meshes result in `(position, normal)` specializations, we can use the same pipeline! Now we do. Cool!

To briefly illustrate, this is what the relevant section of `MeshPipeline`'s specialization code looks like now:

```rust
impl SpecializedMeshPipeline for MeshPipeline {
    type Key = MeshPipelineKey;

    fn specialize(
        &self,
        key: Self::Key,
        layout: &MeshVertexBufferLayout,
    ) -> RenderPipelineDescriptor {
        let mut vertex_attributes = vec![
            Mesh::ATTRIBUTE_POSITION.at_shader_location(0),
            Mesh::ATTRIBUTE_NORMAL.at_shader_location(1),
            Mesh::ATTRIBUTE_UV_0.at_shader_location(2),
        ];

        let mut shader_defs = Vec::new();
        if layout.contains(Mesh::ATTRIBUTE_TANGENT) {
            shader_defs.push(String::from("VERTEX_TANGENTS"));
            vertex_attributes.push(Mesh::ATTRIBUTE_TANGENT.at_shader_location(3));
        }

        let vertex_buffer_layout = layout
            .get_layout(&vertex_attributes)
            .expect("Mesh is missing a vertex attribute");
```

Notice that this is _much_ simpler than it was before. And now any mesh with any layout can be used with this pipeline, provided it has vertex postions, normals, and uvs. We even got to remove `HAS_TANGENTS` from MeshPipelineKey and `has_tangents` from `GpuMesh`, because that information is redundant with `MeshVertexBufferLayout`.

This is still a draft because I still need to:

* Add more docs
* Experiment with adding error handling to mesh pipeline specialization (which would print errors at runtime when a mesh is missing a vertex attribute required by a pipeline). If it doesn't tank perf, we'll keep it.
* Consider breaking out the PreHash / hashbrown changes into a separate PR.
* Add an example illustrating this change
* Verify that the "mesh-specialized pipeline de-duplication code" works properly

Please dont yell at me for not doing these things yet :) Just trying to get this in peoples' hands asap.

Alternative to #3120
Fixes #3030


Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2022-02-23 23:21:13 +00:00