Add push contant config to layout (bevyengine#7681)

# Objective

Allow for creating pipelines that use push constants. To be able to use push constants. Fixes bevyengine#4825

As of right now, trying to call `RenderPass::set_push_constants` will trigger the following error:

```
thread 'main' panicked at 'wgpu error: Validation Error

Caused by:
    In a RenderPass
      note: encoder = `<CommandBuffer-(0, 59, Vulkan)>`
    In a set_push_constant command
    provided push constant is for stage(s) VERTEX | FRAGMENT | VERTEX_FRAGMENT, however the pipeline layout has no push constant range for the stage(s) VERTEX | FRAGMENT | VERTEX_FRAGMENT
```
## Solution

Add a field push_constant_ranges to` RenderPipelineDescriptor` and `ComputePipelineDescriptor`.

This PR supersedes bevyengine#4908 which now contains merge conflicts due to significant changes to `bevy_render`.

Meanwhile, this PR also made the `layout` field of `RenderPipelineDescriptor` and `ComputePipelineDescriptor` non-optional. If the user do not need to specify the bind group layouts, they can simply supply an empty vector here. No need for it to be optional.

---

## Changelog
- Add a field push_constant_ranges to RenderPipelineDescriptor and ComputePipelineDescriptor
- Made the `layout` field of RenderPipelineDescriptor and ComputePipelineDescriptor non-optional.


## Migration Guide

- Add push_constant_ranges: Vec::new() to every `RenderPipelineDescriptor` and `ComputePipelineDescriptor`
- Unwrap the optional values on the `layout` field of `RenderPipelineDescriptor` and `ComputePipelineDescriptor`. If the descriptor has no layout, supply an empty vector.


Co-authored-by: Zhixing Zhang <me@neoto.xin>

crates/bevy_bloom/src/lib.rs

@@ -434,7 +434,7 @@ impl FromWorld for BloomPipelines {
         let downsampling_prefilter_pipeline =
             pipeline_cache.queue_render_pipeline(RenderPipelineDescriptor {
                 label: Some("bloom_downsampling_prefilter_pipeline".into()),
-                layout: Some(vec![downsampling_bind_group_layout.clone()]),
+                layout: vec![downsampling_bind_group_layout.clone()],
                 vertex: fullscreen_shader_vertex_state(),
                 fragment: Some(FragmentState {
                     shader: BLOOM_SHADER_HANDLE.typed::<Shader>(),
@@ -449,12 +449,13 @@ impl FromWorld for BloomPipelines {
                 primitive: PrimitiveState::default(),
                 depth_stencil: None,
                 multisample: MultisampleState::default(),
+                push_constant_ranges: Vec::new(),
             });
 
         let downsampling_pipeline =
             pipeline_cache.queue_render_pipeline(RenderPipelineDescriptor {
                 label: Some("bloom_downsampling_pipeline".into()),
-                layout: Some(vec![downsampling_bind_group_layout.clone()]),
+                layout: vec![downsampling_bind_group_layout.clone()],
                 vertex: fullscreen_shader_vertex_state(),
                 fragment: Some(FragmentState {
                     shader: BLOOM_SHADER_HANDLE.typed::<Shader>(),
@@ -469,11 +470,12 @@ impl FromWorld for BloomPipelines {
                 primitive: PrimitiveState::default(),
                 depth_stencil: None,
                 multisample: MultisampleState::default(),
+                push_constant_ranges: Vec::new(),
             });
 
         let upsampling_pipeline = pipeline_cache.queue_render_pipeline(RenderPipelineDescriptor {
             label: Some("bloom_upsampling_pipeline".into()),
-            layout: Some(vec![upsampling_bind_group_layout.clone()]),
+            layout: vec![upsampling_bind_group_layout.clone()],
             vertex: fullscreen_shader_vertex_state(),
             fragment: Some(FragmentState {
                 shader: BLOOM_SHADER_HANDLE.typed::<Shader>(),
@@ -488,12 +490,13 @@ impl FromWorld for BloomPipelines {
             primitive: PrimitiveState::default(),
             depth_stencil: None,
             multisample: MultisampleState::default(),
+            push_constant_ranges: Vec::new(),
         });
 
         let upsampling_final_pipeline =
             pipeline_cache.queue_render_pipeline(RenderPipelineDescriptor {
                 label: Some("bloom_upsampling_final_pipeline".into()),
-                layout: Some(vec![downsampling_bind_group_layout.clone()]),
+                layout: vec![downsampling_bind_group_layout.clone()],
                 vertex: fullscreen_shader_vertex_state(),
                 fragment: Some(FragmentState {
                     shader: BLOOM_SHADER_HANDLE.typed::<Shader>(),
@@ -515,6 +518,7 @@ impl FromWorld for BloomPipelines {
                 primitive: PrimitiveState::default(),
                 depth_stencil: None,
                 multisample: MultisampleState::default(),
+                push_constant_ranges: Vec::new(),
             });
 
         BloomPipelines {

crates/bevy_fxaa/src/lib.rs

@@ -200,7 +200,7 @@ impl SpecializedRenderPipeline for FxaaPipeline {
     fn specialize(&self, key: Self::Key) -> RenderPipelineDescriptor {
         RenderPipelineDescriptor {
             label: Some("fxaa".into()),
-            layout: Some(vec![self.texture_bind_group.clone()]),
+            layout: vec![self.texture_bind_group.clone()],
             vertex: fullscreen_shader_vertex_state(),
             fragment: Some(FragmentState {
                 shader: FXAA_SHADER_HANDLE.typed(),
@@ -218,6 +218,7 @@ impl SpecializedRenderPipeline for FxaaPipeline {
             primitive: PrimitiveState::default(),
             depth_stencil: None,
             multisample: MultisampleState::default(),
+            push_constant_ranges: Vec::new(),
         }
     }
 }

crates/bevy_pbr/src/material.rs

@@ -289,10 +289,7 @@ where
             descriptor.fragment.as_mut().unwrap().shader = fragment_shader.clone();
         }
 
-        // MeshPipeline::specialize's current implementation guarantees that the returned
-        // specialized descriptor has a populated layout
-        let descriptor_layout = descriptor.layout.as_mut().unwrap();
-        descriptor_layout.insert(1, self.material_layout.clone());
+        descriptor.layout.insert(1, self.material_layout.clone());
 
         M::specialize(self, &mut descriptor, layout, key)?;
         Ok(descriptor)

crates/bevy_pbr/src/prepass/mod.rs

@@ -283,7 +283,7 @@ where
                 buffers: vec![vertex_buffer_layout],
             },
             fragment,
-            layout: Some(bind_group_layout),
+            layout: bind_group_layout,
             primitive: PrimitiveState {
                 topology: key.mesh_key.primitive_topology(),
                 strip_index_format: None,
@@ -314,6 +314,7 @@ where
                 mask: !0,
                 alpha_to_coverage_enabled: false,
             },
+            push_constant_ranges: Vec::new(),
             label: Some("prepass_pipeline".into()),
         };
 

crates/bevy_pbr/src/render/light.rs

@@ -372,7 +372,7 @@ impl SpecializedMeshPipeline for ShadowPipeline {
                 buffers: vec![vertex_buffer_layout],
             },
             fragment: None,
-            layout: Some(bind_group_layout),
+            layout: bind_group_layout,
             primitive: PrimitiveState {
                 topology: key.primitive_topology(),
                 strip_index_format: None,
@@ -400,6 +400,7 @@ impl SpecializedMeshPipeline for ShadowPipeline {
             }),
             multisample: MultisampleState::default(),
             label: Some("shadow_pipeline".into()),
+            push_constant_ranges: Vec::new(),
         })
     }
 }

crates/bevy_pbr/src/render/mesh.rs

@@ -776,7 +776,8 @@ impl SpecializedMeshPipeline for MeshPipeline {
                     write_mask: ColorWrites::ALL,
                 })],
             }),
-            layout: Some(bind_group_layout),
+            layout: bind_group_layout,
+            push_constant_ranges: Vec::new(),
             primitive: PrimitiveState {
                 front_face: FrontFace::Ccw,
                 cull_mode: Some(Face::Back),

crates/bevy_render/src/render_resource/mod.rs

@@ -35,14 +35,14 @@ pub use wgpu::{
     FrontFace, ImageCopyBuffer, ImageCopyBufferBase, ImageCopyTexture, ImageCopyTextureBase,
     ImageDataLayout, ImageSubresourceRange, IndexFormat, Limits as WgpuLimits, LoadOp, MapMode,
     MultisampleState, Operations, Origin3d, PipelineLayout, PipelineLayoutDescriptor, PolygonMode,
-    PrimitiveState, PrimitiveTopology, RenderPassColorAttachment, RenderPassDepthStencilAttachment,
-    RenderPassDescriptor, RenderPipelineDescriptor as RawRenderPipelineDescriptor,
-    SamplerBindingType, SamplerDescriptor, ShaderModule, ShaderModuleDescriptor, ShaderSource,
-    ShaderStages, StencilFaceState, StencilOperation, StencilState, StorageTextureAccess,
-    TextureAspect, TextureDescriptor, TextureDimension, TextureFormat, TextureSampleType,
-    TextureUsages, TextureViewDescriptor, TextureViewDimension, VertexAttribute,
-    VertexBufferLayout as RawVertexBufferLayout, VertexFormat, VertexState as RawVertexState,
-    VertexStepMode,
+    PrimitiveState, PrimitiveTopology, PushConstantRange, RenderPassColorAttachment,
+    RenderPassDepthStencilAttachment, RenderPassDescriptor,
+    RenderPipelineDescriptor as RawRenderPipelineDescriptor, SamplerBindingType, SamplerDescriptor,
+    ShaderModule, ShaderModuleDescriptor, ShaderSource, ShaderStages, StencilFaceState,
+    StencilOperation, StencilState, StorageTextureAccess, TextureAspect, TextureDescriptor,
+    TextureDimension, TextureFormat, TextureSampleType, TextureUsages, TextureViewDescriptor,
+    TextureViewDimension, VertexAttribute, VertexBufferLayout as RawVertexBufferLayout,
+    VertexFormat, VertexState as RawVertexState, VertexStepMode,
 };
 
 pub mod encase {

crates/bevy_render/src/render_resource/pipeline.rs

@@ -7,7 +7,7 @@ use bevy_asset::Handle;
 use std::{borrow::Cow, ops::Deref};
 use wgpu::{
     BufferAddress, ColorTargetState, DepthStencilState, MultisampleState, PrimitiveState,
-    VertexAttribute, VertexFormat, VertexStepMode,
+    PushConstantRange, VertexAttribute, VertexFormat, VertexStepMode,
 };
 
 define_atomic_id!(RenderPipelineId);
@@ -93,7 +93,10 @@ pub struct RenderPipelineDescriptor {
     /// Debug label of the pipeline. This will show up in graphics debuggers for easy identification.
     pub label: Option<Cow<'static, str>>,
     /// The layout of bind groups for this pipeline.
-    pub layout: Option<Vec<BindGroupLayout>>,
+    pub layout: Vec<BindGroupLayout>,
+    /// The push constant ranges for this pipeline.
+    /// Supply an empty vector if the pipeline doesn't use push constants.
+    pub push_constant_ranges: Vec<PushConstantRange>,
     /// The compiled vertex stage, its entry point, and the input buffers layout.
     pub vertex: VertexState,
     /// The properties of the pipeline at the primitive assembly and rasterization level.
@@ -174,7 +177,8 @@ pub struct FragmentState {
 #[derive(Clone, Debug)]
 pub struct ComputePipelineDescriptor {
     pub label: Option<Cow<'static, str>>,
-    pub layout: Option<Vec<BindGroupLayout>>,
+    pub layout: Vec<BindGroupLayout>,
+    pub push_constant_ranges: Vec<PushConstantRange>,
     /// The compiled shader module for this stage.
     pub shader: Handle<Shader>,
     pub shader_defs: Vec<ShaderDefVal>,

crates/bevy_render/src/render_resource/pipeline_cache.rs

@@ -20,7 +20,9 @@ use bevy_utils::{
 use parking_lot::Mutex;
 use std::{hash::Hash, iter::FusedIterator, mem, ops::Deref};
 use thiserror::Error;
-use wgpu::{PipelineLayoutDescriptor, VertexBufferLayout as RawVertexBufferLayout};
+use wgpu::{
+    PipelineLayoutDescriptor, PushConstantRange, VertexBufferLayout as RawVertexBufferLayout,
+};
 
 use crate::render_resource::resource_macros::*;
 
@@ -298,30 +300,35 @@ impl ShaderCache {
     }
 }
 
+type LayoutCacheKey = (Vec<BindGroupLayoutId>, Vec<PushConstantRange>);
 #[derive(Default)]
 struct LayoutCache {
-    layouts: HashMap<Vec<BindGroupLayoutId>, ErasedPipelineLayout>,
+    layouts: HashMap<LayoutCacheKey, ErasedPipelineLayout>,
 }
 
 impl LayoutCache {
     fn get(
         &mut self,
         render_device: &RenderDevice,
         bind_group_layouts: &[BindGroupLayout],
+        push_constant_ranges: Vec<PushConstantRange>,
     ) -> &wgpu::PipelineLayout {
-        let key = bind_group_layouts.iter().map(|l| l.id()).collect();
-        self.layouts.entry(key).or_insert_with(|| {
-            let bind_group_layouts = bind_group_layouts
-                .iter()
-                .map(|l| l.value())
-                .collect::<Vec<_>>();
-            ErasedPipelineLayout::new(render_device.create_pipeline_layout(
-                &PipelineLayoutDescriptor {
-                    bind_group_layouts: &bind_group_layouts,
-                    ..default()
-                },
-            ))
-        })
+        let bind_group_ids = bind_group_layouts.iter().map(|l| l.id()).collect();
+        self.layouts
+            .entry((bind_group_ids, push_constant_ranges))
+            .or_insert_with_key(|(_, push_constant_ranges)| {
+                let bind_group_layouts = bind_group_layouts
+                    .iter()
+                    .map(|l| l.value())
+                    .collect::<Vec<_>>();
+                ErasedPipelineLayout::new(render_device.create_pipeline_layout(
+                    &PipelineLayoutDescriptor {
+                        bind_group_layouts: &bind_group_layouts,
+                        push_constant_ranges,
+                        ..default()
+                    },
+                ))
+            })
     }
 }
 
@@ -561,10 +568,14 @@ impl PipelineCache {
             })
             .collect::<Vec<_>>();
 
-        let layout = if let Some(layout) = &descriptor.layout {
-            Some(self.layout_cache.get(&self.device, layout))
-        } else {
+        let layout = if descriptor.layout.is_empty() && descriptor.push_constant_ranges.is_empty() {
             None
+        } else {
+            Some(self.layout_cache.get(
+                &self.device,
+                &descriptor.layout,
+                descriptor.push_constant_ranges.to_vec(),
+            ))
         };
 
         let descriptor = RawRenderPipelineDescriptor {
@@ -610,10 +621,14 @@ impl PipelineCache {
             }
         };
 
-        let layout = if let Some(layout) = &descriptor.layout {
-            Some(self.layout_cache.get(&self.device, layout))
-        } else {
+        let layout = if descriptor.layout.is_empty() && descriptor.push_constant_ranges.is_empty() {
             None
+        } else {
+            Some(self.layout_cache.get(
+                &self.device,
+                &descriptor.layout,
+                descriptor.push_constant_ranges.to_vec(),
+            ))
         };
 
         let descriptor = RawComputePipelineDescriptor {

crates/bevy_sprite/src/mesh2d/material.rs

@@ -250,11 +250,11 @@ where
         if let Some(fragment_shader) = &self.fragment_shader {
             descriptor.fragment.as_mut().unwrap().shader = fragment_shader.clone();
         }
-        descriptor.layout = Some(vec![
+        descriptor.layout = vec![
             self.mesh2d_pipeline.view_layout.clone(),
             self.material2d_layout.clone(),
             self.mesh2d_pipeline.mesh_layout.clone(),
-        ]);
+        ];
 
         M::specialize(&mut descriptor, layout, key)?;
         Ok(descriptor)

crates/bevy_sprite/src/mesh2d/mesh.rs

@@ -409,7 +409,8 @@ impl SpecializedMeshPipeline for Mesh2dPipeline {
                     write_mask: ColorWrites::ALL,
                 })],
             }),
-            layout: Some(vec![self.view_layout.clone(), self.mesh_layout.clone()]),
+            layout: vec![self.view_layout.clone(), self.mesh_layout.clone()],
+            push_constant_ranges: Vec::new(),
             primitive: PrimitiveState {
                 front_face: FrontFace::Ccw,
                 cull_mode: None,

crates/bevy_sprite/src/render/mod.rs

@@ -247,7 +247,7 @@ impl SpecializedRenderPipeline for SpritePipeline {
                     write_mask: ColorWrites::ALL,
                 })],
             }),
-            layout: Some(vec![self.view_layout.clone(), self.material_layout.clone()]),
+            layout: vec![self.view_layout.clone(), self.material_layout.clone()],
             primitive: PrimitiveState {
                 front_face: FrontFace::Ccw,
                 cull_mode: None,
@@ -264,6 +264,7 @@ impl SpecializedRenderPipeline for SpritePipeline {
                 alpha_to_coverage_enabled: false,
             },
             label: Some("sprite_pipeline".into()),
+            push_constant_ranges: Vec::new(),
         }
     }
 }

crates/bevy_tonemapping/src/lib.rs

@@ -73,7 +73,7 @@ impl SpecializedRenderPipeline for TonemappingPipeline {
         }
         RenderPipelineDescriptor {
             label: Some("tonemapping pipeline".into()),
-            layout: Some(vec![self.texture_bind_group.clone()]),
+            layout: vec![self.texture_bind_group.clone()],
             vertex: fullscreen_shader_vertex_state(),
             fragment: Some(FragmentState {
                 shader: TONEMAPPING_SHADER_HANDLE.typed(),
@@ -88,6 +88,7 @@ impl SpecializedRenderPipeline for TonemappingPipeline {
             primitive: PrimitiveState::default(),
             depth_stencil: None,
             multisample: MultisampleState::default(),
+            push_constant_ranges: Vec::new(),
         }
     }
 }

crates/bevy_ui/src/render/pipeline.rs

@@ -102,7 +102,8 @@ impl SpecializedRenderPipeline for UiPipeline {
                     write_mask: ColorWrites::ALL,
                 })],
             }),
-            layout: Some(vec![self.view_layout.clone(), self.image_layout.clone()]),
+            layout: vec![self.view_layout.clone(), self.image_layout.clone()],
+            push_constant_ranges: Vec::new(),
             primitive: PrimitiveState {
                 front_face: FrontFace::Ccw,
                 cull_mode: None,

crates/bevy_upscaling/src/lib.rs

@@ -89,7 +89,7 @@ impl SpecializedRenderPipeline for UpscalingPipeline {
     fn specialize(&self, key: Self::Key) -> RenderPipelineDescriptor {
         RenderPipelineDescriptor {
             label: Some("upscaling pipeline".into()),
-            layout: Some(vec![self.texture_bind_group.clone()]),
+            layout: vec![self.texture_bind_group.clone()],
             vertex: fullscreen_shader_vertex_state(),
             fragment: Some(FragmentState {
                 shader: UPSCALING_SHADER_HANDLE.typed(),
@@ -104,6 +104,7 @@ impl SpecializedRenderPipeline for UpscalingPipeline {
             primitive: PrimitiveState::default(),
             depth_stencil: None,
             multisample: MultisampleState::default(),
+            push_constant_ranges: Vec::new(),
         }
     }
 }

examples/2d/mesh2d_manual.rs

@@ -172,12 +172,13 @@ impl SpecializedRenderPipeline for ColoredMesh2dPipeline {
                 })],
             }),
             // Use the two standard uniforms for 2d meshes
-            layout: Some(vec![
+            layout: vec![
                 // Bind group 0 is the view uniform
                 self.mesh2d_pipeline.view_layout.clone(),
                 // Bind group 1 is the mesh uniform
                 self.mesh2d_pipeline.mesh_layout.clone(),
-            ]),
+            ],
+            push_constant_ranges: Vec::new(),
             primitive: PrimitiveState {
                 front_face: FrontFace::Ccw,
                 cull_mode: Some(Face::Back),