# Objective
Since #8446, example `shader_prepass` logs the following error on my mac
m1:
```
ERROR bevy_render::render_resource::pipeline_cache: failed to process shader:
error: Entry point fragment at Fragment is invalid
= Argument 1 varying error
= Capability MULTISAMPLED_SHADING is not supported
```
The example display the 3d scene but doesn't change with the preps
selected
Maybe related to this update in naga:
cc3a8ac737
## Solution
- Disable MSAA in the example, and check if it's enabled in the shader
# 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
- Use the prepass textures in webgl
## Solution
- Bind the prepass textures even when using webgl, but only if msaa is disabled
- Also did some refactors to centralize how textures are bound, similar to the EnvironmentMapLight PR
- ~~Also did some refactors of the example to make it work in webgl~~
- ~~To make the example work in webgl, I needed to use a sampler for the depth texture, the resulting code looks a bit weird, but it's simple enough and I think it's worth it to show how it works when using webgl~~
# Objective
- The functions added to utils.wgsl by the prepass assume that mesh_view_bindings are present, which isn't always the case
- Fixes https://github.com/bevyengine/bevy/issues/7353
## Solution
- Move these functions to their own `prepass_utils.wgsl` file
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
# 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>
