# Objective
- Right now we can't really benefit from [early depth
testing](https://www.khronos.org/opengl/wiki/Early_Fragment_Test) in our
PBR shader because it includes codepaths with `discard`, even for
situations where they are not necessary.
## Solution
- This PR introduces a new `MeshPipelineKey` and shader def,
`MAY_DISCARD`;
- All possible material/mesh options that that may result in `discard`s
being needed must set `MAY_DISCARD` ahead of time:
- Right now, this is only `AlphaMode::Mask(f32)`, but in the future
might include other options/effects; (e.g. one effect I'm personally
interested in is bayer dither pseudo-transparency for LOD transitions of
opaque meshes)
- Shader codepaths that can `discard` are guarded by an `#ifdef
MAY_DISCARD` preprocessor directive:
- Right now, this is just one branch in `alpha_discard()`;
- If `MAY_DISCARD` is _not_ set, the `@early_depth_test` attribute is
added to the PBR fragment shader. This is a not yet documented, possibly
non-standard WGSL extension I found browsing Naga's source code. [I
opened a PR to document it
there](https://github.com/gfx-rs/naga/pull/2132). My understanding is
that for backends where this attribute is supported, it will force an
explicit opt-in to early depth test. (e.g. via
`layout(early_fragment_tests) in;` in GLSL)
## Caveats
- I included `@early_depth_test` for the sake of us being explicit, and
avoiding the need for the driver to be “smart” about enabling this
feature. That way, if we make a mistake and include a `discard`
unguarded by `MAY_DISCARD`, it will either produce errors or noticeable
visual artifacts so that we'll catch early, instead of causing a
performance regression.
- I'm not sure explicit early depth test is supported on the naga Metal
backend, which is what I'm currently using, so I can't really test the
explicit early depth test enable, I would like others with Vulkan/GL
hardware to test it if possible;
- I would like some guidance on how to measure/verify the performance
benefits of this;
- If I understand it correctly, this, or _something like this_ is needed
to fully reap the performance gains enabled by #6284;
- This will _most definitely_ conflict with #6284 and #6644. I can fix
the conflicts as needed, depending on whether/the order they end up
being merging in.
---
## Changelog
### Changed
- Early depth tests are now enabled whenever possible for meshes using
`StandardMaterial`, reducing the number of fragments evaluated for
scenes with lots of occlusions.
# Objective
- Implement an alternative antialias technique
- TAA scales based off of view resolution, not geometry complexity
- TAA filters textures, firefly pixels, and other aliasing not covered
by MSAA
- TAA additionally will reduce noise / increase quality in future
stochastic rendering techniques
- Closes https://github.com/bevyengine/bevy/issues/3663
## Solution
- Add a temporal jitter component
- Add a motion vector prepass
- Add a TemporalAntialias component and plugin
- Combine existing MSAA and FXAA examples and add TAA
## Followup Work
- Prepass motion vector support for skinned meshes
- Move uniforms needed for motion vectors into a separate bind group,
instead of using different bind group layouts
- Reuse previous frame's GPU view buffer for motion vectors, instead of
recomputing
- Mip biasing for sharper textures, and or unjitter texture UVs
https://github.com/bevyengine/bevy/issues/7323
- Compute shader for better performance
- Investigate FSR techniques
- Historical depth based disocclusion tests, for geometry disocclusion
- Historical luminance/hue based tests, for shading disocclusion
- Pixel "locks" to reduce blending rate / revamp history confidence
mechanism
- Orthographic camera support for TemporalJitter
- Figure out COD's 1-tap bicubic filter
---
## Changelog
- Added MotionVectorPrepass and TemporalJitter
- Added TemporalAntialiasPlugin, TemporalAntialiasBundle, and
TemporalAntialiasSettings
---------
Co-authored-by: IceSentry <c.giguere42@gmail.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: Daniel Chia <danstryder@gmail.com>
Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com>
Co-authored-by: Brandon Dyer <brandondyer64@gmail.com>
Co-authored-by: Edgar Geier <geieredgar@gmail.com>
# Objective
revert combining pipelines for AlphaMode::Blend and AlphaMode::Premultiplied & Add
the recent blend state pr changed `AlphaMode::Blend` to use a blend state of `Blend::PREMULTIPLIED_ALPHA_BLENDING`, and recovered the original behaviour by multiplying colour by alpha in the standard material's fragment shader.
this had some advantages (specifically it means more material instances can be batched together in future), but this also means that custom materials that specify `AlphaMode::Blend` now get a premultiplied blend state, so they must also multiply colour by alpha.
## Solution
revert that combination to preserve 0.9 behaviour for custom materials with AlphaMode::Blend.
# Objective
- Fixes#4372.
## Solution
- Use the prepass shaders for the shadow passes.
- Move `DEPTH_CLAMP_ORTHO` from `ShadowPipelineKey` to `MeshPipelineKey` and the associated clamp operation from `depth.wgsl` to `prepass.wgsl`.
- Remove `depth.wgsl` .
- Replace `ShadowPipeline` with `ShadowSamplers`.
Instead of running the custom `ShadowPipeline` we run the `PrepassPipeline` with the `DEPTH_PREPASS` flag and additionally the `DEPTH_CLAMP_ORTHO` flag for directional lights as well as the `ALPHA_MASK` flag for materials that use `AlphaMode::Mask(_)`.
# Objective
- Add a configurable prepass
- A depth prepass is useful for various shader effects and to reduce overdraw. It can be expansive depending on the scene so it's important to be able to disable it if you don't need any effects that uses it or don't suffer from excessive overdraw.
- The goal is to eventually use it for things like TAA, Ambient Occlusion, SSR and various other techniques that can benefit from having a prepass.
## Solution
The prepass node is inserted before the main pass. It runs for each `Camera3d` with a prepass component (`DepthPrepass`, `NormalPrepass`). The presence of one of those components is used to determine which textures are generated in the prepass. When any prepass is enabled, the depth buffer generated will be used by the main pass to reduce overdraw.
The prepass runs for each `Material` created with the `MaterialPlugin::prepass_enabled` option set to `true`. You can overload the shader used by the prepass by using `Material::prepass_vertex_shader()` and/or `Material::prepass_fragment_shader()`. It will also use the `Material::specialize()` for more advanced use cases. It is enabled by default on all materials.
The prepass works on opaque materials and materials using an alpha mask. Transparent materials are ignored.
The `StandardMaterial` overloads the prepass fragment shader to support alpha mask and normal maps.
---
## Changelog
- Add a new `PrepassNode` that runs before the main pass
- Add a `PrepassPlugin` to extract/prepare/queue the necessary data
- Add a `DepthPrepass` and `NormalPrepass` component to control which textures will be created by the prepass and available in later passes.
- Add a new `prepass_enabled` flag to the `MaterialPlugin` that will control if a material uses the prepass or not.
- Add a new `prepass_enabled` flag to the `PbrPlugin` to control if the StandardMaterial uses the prepass. Currently defaults to false.
- Add `Material::prepass_vertex_shader()` and `Material::prepass_fragment_shader()` to control the prepass from the `Material`
## Notes
In bevy's sample 3d scene, the performance is actually worse when enabling the prepass, but on more complex scenes the performance is generally better. I would like more testing on this, but @DGriffin91 has reported a very noticeable improvements in some scenes.
The prepass is also used by @JMS55 for TAA and GTAO
discord thread: <https://discord.com/channels/691052431525675048/1011624228627419187>
This PR was built on top of the work of multiple people
Co-Authored-By: @superdump
Co-Authored-By: @robtfm
Co-Authored-By: @JMS55
Co-authored-by: Charles <IceSentry@users.noreply.github.com>
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
