Shaders: runtime and shader node codegen (#2985)

* shader-rt: initial

* shader-rt: fix recursion when generating shader node

* shader-rt: replace gpu node's args and ret types with `Raster<GPU>`

* shader-rt: properly cfg out the gpu node

* shader-rt: fix `impl Context` in the wrong places

* shader-rt: disable gpu blend node, needs two images

* shader-rt: connect shader runtime

* shader-rt: pass WgpuExecutor by reference

* shader-rt: correct bindings with derpy arg buffer

* shader-rt: manual pipeline layout, fixing errors when bindings got DCE'd

* shader-rt: correct RT format, working invert gpu node

* shader-rt: cleanup codegen with common sym struct

* shader-rt: correct arg buffer handling

* shader-nodes feature: put shader nodes behind feature gate

* shader-nodes feature: rename any `gpu_node` to `shader-node`

* shaders-rt: fix wgpu label name

* shaders-rt: explain fullscreen_vertex coordinates with a drawing

node-graph/node-macro/src/shader_nodes/mod.rs

@@ -3,24 +3,38 @@ use crate::shader_nodes::per_pixel_adjust::PerPixelAdjust;
 use proc_macro2::{Ident, TokenStream};
 use quote::quote;
 use strum::VariantNames;
-use syn::Error;
 use syn::parse::{Parse, ParseStream};
+use syn::punctuated::Punctuated;
+use syn::{Error, Token};
 
 pub mod per_pixel_adjust;
 
 pub const STD_FEATURE_GATE: &str = "std";
+pub const SHADER_NODES_FEATURE_GATE: &str = "shader-nodes";
 
 pub fn modify_cfg(attributes: &NodeFnAttributes) -> TokenStream {
-	match (&attributes.cfg, &attributes.shader_node) {
-		(Some(cfg), Some(_)) => quote!(#[cfg(all(#cfg, feature = #STD_FEATURE_GATE))]),
-		(Some(cfg), None) => quote!(#[cfg(#cfg)]),
-		(None, Some(_)) => quote!(#[cfg(feature = #STD_FEATURE_GATE)]),
-		(None, None) => quote!(),
-	}
+	let feature_gate = match &attributes.shader_node {
+		// shader node cfg is done on the mod
+		Some(ShaderNodeType::ShaderNode) => quote!(),
+		Some(_) => quote!(feature = #STD_FEATURE_GATE),
+		None => quote!(),
+	};
+	let cfgs: Punctuated<_, Token![,]> = match &attributes.cfg {
+		None => [&feature_gate].into_iter().collect(),
+		Some(cfg) => [cfg, &feature_gate].into_iter().collect(),
+	};
+	quote!(#[cfg(all(#cfgs))])
 }
 
-#[derive(Debug, VariantNames)]
+#[derive(Debug, Clone, VariantNames)]
 pub(crate) enum ShaderNodeType {
+	/// Marker for this node being in a gpu node crate, but not having a gpu implementation. This is distinct from not
+	/// declaring `shader_node` at all, as it will wrap the CPU node with a `#[cfg(feature = "std")]` feature gate.
+	None,
+	/// Marker for this node being a generated gpu node implementation, that should not emit anything to prevent
+	/// recursively generating more gpu nodes. But it still counts as a gpu node and will get the
+	/// `#[cfg(feature = "std")]` feature gate around it's impl.
+	ShaderNode,
 	PerPixelAdjust(PerPixelAdjust),
 }
 
@@ -28,24 +42,37 @@ impl Parse for ShaderNodeType {
 	fn parse(input: ParseStream) -> syn::Result<Self> {
 		let ident: Ident = input.parse()?;
 		Ok(match ident.to_string().as_str() {
+			"None" => ShaderNodeType::None,
 			"PerPixelAdjust" => ShaderNodeType::PerPixelAdjust(PerPixelAdjust::parse(input)?),
 			_ => return Err(Error::new_spanned(&ident, format!("attr 'shader_node' must be one of {:?}", Self::VARIANTS))),
 		})
 	}
 }
 
-pub trait CodegenShaderEntryPoint {
-	fn codegen_shader_entry_point(&self, parsed: &ParsedNodeFn) -> syn::Result<TokenStream>;
+pub trait ShaderCodegen {
+	fn codegen(&self, parsed: &ParsedNodeFn) -> syn::Result<ShaderTokens>;
 }
 
-impl CodegenShaderEntryPoint for ShaderNodeType {
-	fn codegen_shader_entry_point(&self, parsed: &ParsedNodeFn) -> syn::Result<TokenStream> {
-		if parsed.is_async {
-			return Err(Error::new_spanned(&parsed.fn_name, "Shader nodes must not be async"));
+impl ShaderCodegen for ShaderNodeType {
+	fn codegen(&self, parsed: &ParsedNodeFn) -> syn::Result<ShaderTokens> {
+		match self {
+			ShaderNodeType::None | ShaderNodeType::ShaderNode => (),
+			_ => {
+				if parsed.is_async {
+					return Err(Error::new_spanned(&parsed.fn_name, "Shader nodes must not be async"));
+				}
+			}
 		}
 
 		match self {
-			ShaderNodeType::PerPixelAdjust(x) => x.codegen_shader_entry_point(parsed),
+			ShaderNodeType::None | ShaderNodeType::ShaderNode => Ok(ShaderTokens::default()),
+			ShaderNodeType::PerPixelAdjust(x) => x.codegen(parsed),
 		}
 	}
 }
+
+#[derive(Clone, Default)]
+pub struct ShaderTokens {
+	pub shader_entry_point: TokenStream,
+	pub gpu_node: TokenStream,
+}

node-graph/node-macro/src/shader_nodes/per_pixel_adjust.rs

@@ -1,11 +1,15 @@
-use crate::parsing::{ParsedFieldType, ParsedNodeFn, RegularParsedField};
-use crate::shader_nodes::CodegenShaderEntryPoint;
+use crate::parsing::{Input, NodeFnAttributes, ParsedField, ParsedFieldType, ParsedNodeFn, RegularParsedField};
+use crate::shader_nodes::{SHADER_NODES_FEATURE_GATE, ShaderCodegen, ShaderNodeType, ShaderTokens};
+use convert_case::{Case, Casing};
+use proc_macro_crate::FoundCrate;
 use proc_macro2::{Ident, TokenStream};
 use quote::{ToTokens, format_ident, quote};
 use std::borrow::Cow;
 use syn::parse::{Parse, ParseStream};
+use syn::punctuated::Punctuated;
+use syn::{PatIdent, Type, parse_quote};
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct PerPixelAdjust {}
 
 impl Parse for PerPixelAdjust {
@@ -14,53 +18,113 @@ impl Parse for PerPixelAdjust {
 	}
 }
 
-impl CodegenShaderEntryPoint for PerPixelAdjust {
-	fn codegen_shader_entry_point(&self, parsed: &ParsedNodeFn) -> syn::Result<TokenStream> {
+impl ShaderCodegen for PerPixelAdjust {
+	fn codegen(&self, parsed: &ParsedNodeFn) -> syn::Result<ShaderTokens> {
 		let fn_name = &parsed.fn_name;
-		let gpu_mod = format_ident!("{}_gpu", parsed.fn_name);
-		let spirv_image_ty = quote!(Image2d);
 
-		// bindings for images start at 1
-		let mut binding_cnt = 0;
-		let params = parsed
-			.fields
-			.iter()
-			.map(|f| {
-				let ident = &f.pat_ident;
-				match &f.ty {
-					ParsedFieldType::Node { .. } => Err(syn::Error::new_spanned(ident, "PerPixelAdjust shader nodes cannot accept other nodes as generics")),
-					ParsedFieldType::Regular(RegularParsedField { gpu_image: false, ty, .. }) => Ok(Param {
-						ident: Cow::Borrowed(&ident.ident),
-						ty: Cow::Owned(ty.to_token_stream()),
-						param_type: ParamType::Uniform,
-					}),
-					ParsedFieldType::Regular(RegularParsedField { gpu_image: true, .. }) => {
-						binding_cnt += 1;
-						Ok(Param {
-							ident: Cow::Owned(format_ident!("image_{}", &ident.ident)),
-							ty: Cow::Borrowed(&spirv_image_ty),
-							param_type: ParamType::Image { binding: binding_cnt },
-						})
+		let mut params;
+		let has_uniform;
+		{
+			// categorize params
+			params = parsed
+				.fields
+				.iter()
+				.map(|f| {
+					let ident = &f.pat_ident;
+					match &f.ty {
+						ParsedFieldType::Node { .. } => Err(syn::Error::new_spanned(ident, "PerPixelAdjust shader nodes cannot accept other nodes as generics")),
+						ParsedFieldType::Regular(RegularParsedField { gpu_image: false, ty, .. }) => Ok(Param {
+							ident: Cow::Borrowed(&ident.ident),
+							ty: ty.to_token_stream(),
+							param_type: ParamType::Uniform,
+						}),
+						ParsedFieldType::Regular(RegularParsedField { gpu_image: true, .. }) => {
+							let param = Param {
+								ident: Cow::Owned(format_ident!("image_{}", &ident.ident)),
+								ty: quote!(Image2d),
+								param_type: ParamType::Image { binding: 0 },
+							};
+							Ok(param)
+						}
 					}
-				}
-			})
-			.collect::<syn::Result<Vec<_>>>()?;
+				})
+				.collect::<syn::Result<Vec<_>>>()?;
 
-		let uniform_members = params
+			has_uniform = params.iter().any(|p| matches!(p.param_type, ParamType::Uniform));
+
+			// assign image bindings
+			// if an arg_buffer exists, bindings for images start at 1 to leave 0 for arg buffer
+			let mut binding_cnt = if has_uniform { 1 } else { 0 };
+			for p in params.iter_mut() {
+				match &mut p.param_type {
+					ParamType::Image { binding } => {
+						*binding = binding_cnt;
+						binding_cnt += 1;
+					}
+					ParamType::Uniform => {}
+				}
+			}
+		}
+
+		let entry_point_mod = format_ident!("{}_gpu_entry_point", fn_name);
+		let entry_point_name_ident = format_ident!("ENTRY_POINT_NAME");
+		let entry_point_name = quote!(#entry_point_mod::#entry_point_name_ident);
+		let uniform_struct_ident = format_ident!("Uniform");
+		let uniform_struct = quote!(#entry_point_mod::#uniform_struct_ident);
+		let shader_node_mod = format_ident!("{}_shader_node", fn_name);
+
+		let codegen = PerPixelAdjustCodegen {
+			parsed,
+			params,
+			has_uniform,
+			entry_point_mod,
+			entry_point_name_ident,
+			entry_point_name,
+			uniform_struct_ident,
+			uniform_struct,
+			shader_node_mod,
+		};
+
+		Ok(ShaderTokens {
+			shader_entry_point: codegen.codegen_shader_entry_point()?,
+			gpu_node: codegen.codegen_gpu_node()?,
+		})
+	}
+}
+
+pub struct PerPixelAdjustCodegen<'a> {
+	parsed: &'a ParsedNodeFn,
+	params: Vec<Param<'a>>,
+	has_uniform: bool,
+	entry_point_mod: Ident,
+	entry_point_name_ident: Ident,
+	entry_point_name: TokenStream,
+	uniform_struct_ident: Ident,
+	uniform_struct: TokenStream,
+	shader_node_mod: Ident,
+}
+
+impl PerPixelAdjustCodegen<'_> {
+	fn codegen_shader_entry_point(&self) -> syn::Result<TokenStream> {
+		let fn_name = &self.parsed.fn_name;
+		let uniform_members = self
+			.params
 			.iter()
 			.filter_map(|Param { ident, ty, param_type }| match param_type {
 				ParamType::Image { .. } => None,
 				ParamType::Uniform => Some(quote! {#ident: #ty}),
 			})
 			.collect::<Vec<_>>();
-		let image_params = params
+		let image_params = self
+			.params
 			.iter()
 			.filter_map(|Param { ident, ty, param_type }| match param_type {
 				ParamType::Image { binding } => Some(quote! {#[spirv(descriptor_set = 0, binding = #binding)] #ident: &#ty}),
 				ParamType::Uniform => None,
 			})
 			.collect::<Vec<_>>();
-		let call_args = params
+		let call_args = self
+			.params
 			.iter()
 			.map(|Param { ident, param_type, .. }| match param_type {
 				ParamType::Image { .. } => quote!(Color::from_vec4(#ident.fetch_with(texel_coord, lod(0)))),
@@ -69,8 +133,11 @@ impl CodegenShaderEntryPoint for PerPixelAdjust {
 			.collect::<Vec<_>>();
 		let context = quote!(());
 
+		let entry_point_mod = &self.entry_point_mod;
+		let entry_point_name = &self.entry_point_name_ident;
+		let uniform_struct_ident = &self.uniform_struct_ident;
 		Ok(quote! {
-			pub mod #gpu_mod {
+			pub mod #entry_point_mod {
 				use super::*;
 				use graphene_core_shaders::color::Color;
 				use spirv_std::spirv;
@@ -78,8 +145,12 @@ impl CodegenShaderEntryPoint for PerPixelAdjust {
 				use spirv_std::image::{Image2d, ImageWithMethods};
 				use spirv_std::image::sample_with::lod;
 
-				pub struct Uniform {
-					#(#uniform_members),*
+				pub const #entry_point_name: &str = core::concat!(core::module_path!(), "::entry_point");
+
+				#[repr(C)]
+				#[derive(Copy, Clone, bytemuck::NoUninit)]
+				pub struct #uniform_struct_ident {
+					#(pub #uniform_members),*
 				}
 
 				#[spirv(fragment)]
@@ -96,11 +167,162 @@ impl CodegenShaderEntryPoint for PerPixelAdjust {
 			}
 		})
 	}
+
+	fn codegen_gpu_node(&self) -> syn::Result<TokenStream> {
+		let gcore = match &self.parsed.crate_name {
+			FoundCrate::Itself => format_ident!("crate"),
+			FoundCrate::Name(name) => format_ident!("{name}"),
+		};
+
+		// adapt fields for gpu node
+		let raster_gpu: Type = parse_quote!(#gcore::table::Table<#gcore::raster_types::Raster<#gcore::raster_types::GPU>>);
+		let mut fields = self
+			.parsed
+			.fields
+			.iter()
+			.map(|f| match &f.ty {
+				ParsedFieldType::Regular(reg @ RegularParsedField { gpu_image: true, .. }) => Ok(ParsedField {
+					pat_ident: PatIdent {
+						mutability: None,
+						by_ref: None,
+						..f.pat_ident.clone()
+					},
+					ty: ParsedFieldType::Regular(RegularParsedField {
+						ty: raster_gpu.clone(),
+						implementations: Punctuated::default(),
+						..reg.clone()
+					}),
+					..f.clone()
+				}),
+				ParsedFieldType::Regular(RegularParsedField { gpu_image: false, .. }) => Ok(ParsedField {
+					pat_ident: PatIdent {
+						mutability: None,
+						by_ref: None,
+						..f.pat_ident.clone()
+					},
+					..f.clone()
+				}),
+				ParsedFieldType::Node { .. } => Err(syn::Error::new_spanned(&f.pat_ident, "PerPixelAdjust shader nodes cannot accept other nodes as generics")),
+			})
+			.collect::<syn::Result<Vec<_>>>()?;
+
+		// insert wgpu_executor field
+		let wgpu_executor = format_ident!("__wgpu_executor");
+		fields.push(ParsedField {
+			pat_ident: PatIdent {
+				attrs: vec![],
+				by_ref: None,
+				mutability: None,
+				ident: parse_quote!(#wgpu_executor),
+				subpat: None,
+			},
+			name: None,
+			description: "".to_string(),
+			widget_override: Default::default(),
+			ty: ParsedFieldType::Regular(RegularParsedField {
+				ty: parse_quote!(&'a WgpuExecutor),
+				exposed: false,
+				value_source: Default::default(),
+				number_soft_min: None,
+				number_soft_max: None,
+				number_hard_min: None,
+				number_hard_max: None,
+				number_mode_range: None,
+				implementations: Default::default(),
+				gpu_image: false,
+			}),
+			number_display_decimal_places: None,
+			number_step: None,
+			unit: None,
+		});
+
+		// find exactly one gpu_image field, runtime doesn't support more than 1 atm
+		let gpu_image_field = {
+			let mut iter = fields.iter().filter(|f| matches!(f.ty, ParsedFieldType::Regular(RegularParsedField { gpu_image: true, .. })));
+			match (iter.next(), iter.next()) {
+				(Some(v), None) => Ok(v),
+				(Some(_), Some(more)) => Err(syn::Error::new_spanned(&more.pat_ident, "No more than one parameter must be annotated with `#[gpu_image]`")),
+				(None, _) => Err(syn::Error::new_spanned(&self.parsed.fn_name, "At least one parameter must be annotated with `#[gpu_image]`")),
+			}?
+		};
+		let gpu_image = &gpu_image_field.pat_ident.ident;
+
+		// uniform buffer struct construction
+		let has_uniform = self.has_uniform;
+		let uniform_buffer = if has_uniform {
+			let uniform_struct = &self.uniform_struct;
+			let uniform_members = self
+				.params
+				.iter()
+				.filter_map(|p| match p.param_type {
+					ParamType::Image { .. } => None,
+					ParamType::Uniform => Some(p.ident.as_ref()),
+				})
+				.collect::<Vec<_>>();
+			quote!(Some(&super::#uniform_struct {
+				#(#uniform_members),*
+			}))
+		} else {
+			// explicit generics placed here cause it's easier than explicitly writing `run_per_pixel_adjust::<()>`
+			quote!(Option::<&()>::None)
+		};
+
+		// node function body
+		let entry_point_name = &self.entry_point_name;
+		let body = quote! {
+			{
+				#wgpu_executor.shader_runtime.run_per_pixel_adjust(&::wgpu_executor::shader_runtime::per_pixel_adjust_runtime::Shaders {
+					wgsl_shader: crate::WGSL_SHADER,
+					fragment_shader_name: super::#entry_point_name,
+					has_uniform: #has_uniform,
+				}, #gpu_image, #uniform_buffer).await
+			}
+		};
+
+		// call node codegen
+		let mut parsed_node_fn = ParsedNodeFn {
+			vis: self.parsed.vis.clone(),
+			attributes: NodeFnAttributes {
+				shader_node: Some(ShaderNodeType::ShaderNode),
+				..self.parsed.attributes.clone()
+			},
+			fn_name: self.shader_node_mod.clone(),
+			struct_name: format_ident!("{}", self.shader_node_mod.to_string().to_case(Case::Pascal)),
+			mod_name: self.shader_node_mod.clone(),
+			fn_generics: vec![parse_quote!('a: 'n)],
+			where_clause: None,
+			input: Input {
+				pat_ident: self.parsed.input.pat_ident.clone(),
+				ty: parse_quote!(impl #gcore::context::Ctx),
+				implementations: Default::default(),
+			},
+			output_type: raster_gpu,
+			is_async: true,
+			fields,
+			body,
+			crate_name: self.parsed.crate_name.clone(),
+			description: "".to_string(),
+		};
+		parsed_node_fn.replace_impl_trait_in_input();
+		let gpu_node_impl = crate::codegen::generate_node_code(&parsed_node_fn)?;
+
+		// wrap node in `mod #gpu_node_mod`
+		let shader_node_mod = &self.shader_node_mod;
+		Ok(quote! {
+			#[cfg(feature = #SHADER_NODES_FEATURE_GATE)]
+			mod #shader_node_mod {
+				use super::*;
+				use wgpu_executor::WgpuExecutor;
+
+				#gpu_node_impl
+			}
+		})
+	}
 }
 
 struct Param<'a> {
 	ident: Cow<'a, Ident>,
-	ty: Cow<'a, TokenStream>,
+	ty: TokenStream,
 	param_type: ParamType,
 }