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bevy/crates/bevy_pbr/src/prepass/prepass_io.wgsl

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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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/render/pbr.wgsl#L168). - The deferred lighting pass unpacks the `PbrInput` and [feeds it into the pbr() function](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl#L65), then outputs the shaded color data. - There is now a resource [DefaultOpaqueRendererMethod](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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()](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/b79182d2a32cac28c4213c2457a53ac2cc885332/crates/bevy_pbr/src/prepass/prepass_io.wgsl#L95) attachment. The custom deferred lighting pass plugin can then set [its corresponding depth](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl#L37). Then with the lighting pass using [CompareFunction::Equal](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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
#define_import_path bevy_pbr::prepass_io
// Most of these attributes are not used in the default prepass fragment shader, but they are still needed so we can
// pass them to custom prepass shaders like pbr_prepass.wgsl.
struct Vertex {
@builtin(instance_index) instance_index: u32,
@location(0) position: vec3<f32>,
#ifdef VERTEX_UVS
@location(1) uv: vec2<f32>,
#endif
#ifdef NORMAL_PREPASS_OR_DEFERRED_PREPASS
@location(2) normal: vec3<f32>,
#ifdef VERTEX_TANGENTS
@location(3) tangent: vec4<f32>,
#endif
#endif // NORMAL_PREPASS_OR_DEFERRED_PREPASS
#ifdef SKINNED
@location(4) joint_indices: vec4<u32>,
@location(5) joint_weights: vec4<f32>,
#endif
#ifdef VERTEX_COLORS
@location(6) color: vec4<f32>,
#endif
#ifdef MORPH_TARGETS
@builtin(vertex_index) index: u32,
#endif // MORPH_TARGETS
}
struct VertexOutput {
pbr shader cleanup (#10105) # Objective cleanup some pbr shader code. improve shader stage io consistency and make pbr.wgsl (probably many people's first foray into bevy shader code) a little more human-readable. also fix a couple of small issues with deferred rendering. ## Solution mesh_vertex_output: - rename to forward_io (to align with prepass_io) - rename `MeshVertexOutput` to `VertexOutput` (to align with prepass_io) - move `Vertex` from mesh.wgsl into here (to align with prepass_io) prepass_io: - remove `FragmentInput`, use `VertexOutput` directly (to align with forward_io) - rename `VertexOutput::clip_position` to `position` (to align with forward_io) pbr.wgsl: - restructure so we don't need `#ifdefs` on the actual entrypoint, use VertexOutput and FragmentOutput in all cases and use #ifdefs to import the right struct definitions. - rearrange to make the flow clearer - move alpha_discard up from `pbr_functions::pbr` to avoid needing to call it on some branches and not others - add a bunch of comments deferred_lighting: - move ssao into the `!unlit` block to reflect forward behaviour correctly - fix compile error with deferred + premultiply_alpha ## Migration Guide in custom material shaders: - `pbr_functions::pbr` no longer calls to `pbr_functions::alpha_discard`. if you were using the `pbr` function in a custom shader with alpha mask mode you now also need to call alpha_discard manually - rename imports of `bevy_pbr::mesh_vertex_output` to `bevy_pbr::forward_io` - rename instances of `MeshVertexOutput` to `VertexOutput` in custom material prepass shaders: - rename instances of `VertexOutput::clip_position` to `VertexOutput::position`
2023-10-13 19:12:40 +00:00
// This is `clip position` when the struct is used as a vertex stage output
// and `frag coord` when used as a fragment stage input
@builtin(position) position: vec4<f32>,
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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/render/pbr.wgsl#L168). - The deferred lighting pass unpacks the `PbrInput` and [feeds it into the pbr() function](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl#L65), then outputs the shaded color data. - There is now a resource [DefaultOpaqueRendererMethod](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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()](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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](https://github.com/DGriffin91/bevy/blob/b79182d2a32cac28c4213c2457a53ac2cc885332/crates/bevy_pbr/src/prepass/prepass_io.wgsl#L95) attachment. The custom deferred lighting pass plugin can then set [its corresponding depth](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/crates/bevy_pbr/src/deferred/deferred_lighting.wgsl#L37). Then with the lighting pass using [CompareFunction::Equal](https://github.com/DGriffin91/bevy/blob/ec1465559f2c82001830e908fc02ff1d7c2efe51/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
#ifdef VERTEX_UVS
@location(0) uv: vec2<f32>,
#endif
#ifdef NORMAL_PREPASS_OR_DEFERRED_PREPASS
@location(1) world_normal: vec3<f32>,
#ifdef VERTEX_TANGENTS
@location(2) world_tangent: vec4<f32>,
#endif
#endif // NORMAL_PREPASS_OR_DEFERRED_PREPASS
@location(3) world_position: vec4<f32>,
#ifdef MOTION_VECTOR_PREPASS
@location(4) previous_world_position: vec4<f32>,
#endif
#ifdef DEPTH_CLAMP_ORTHO
@location(5) clip_position_unclamped: vec4<f32>,
#endif // DEPTH_CLAMP_ORTHO
#ifdef VERTEX_OUTPUT_INSTANCE_INDEX
@location(6) instance_index: u32,
#endif
#ifdef VERTEX_COLORS
@location(7) color: vec4<f32>,
#endif
}
#ifdef PREPASS_FRAGMENT
struct FragmentOutput {
#ifdef NORMAL_PREPASS
@location(0) normal: vec4<f32>,
#endif
#ifdef MOTION_VECTOR_PREPASS
@location(1) motion_vector: vec2<f32>,
#endif
#ifdef DEFERRED_PREPASS
@location(2) deferred: vec4<u32>,
@location(3) deferred_lighting_pass_id: u32,
#endif
#ifdef DEPTH_CLAMP_ORTHO
@builtin(frag_depth) frag_depth: f32,
#endif // DEPTH_CLAMP_ORTHO
}
#endif //PREPASS_FRAGMENT
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