shader-rt: fix recursion when generating shader node

Author: Firestar99

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

@@ -21,6 +21,10 @@ pub fn modify_cfg(attributes: &NodeFnAttributes) -> TokenStream {
 
 #[derive(Debug, Clone, VariantNames)]
 pub(crate) enum ShaderNodeType {
+	/// 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.
+	GpuNode,
 	PerPixelAdjust(PerPixelAdjust),
 }
 
@@ -41,17 +45,24 @@ pub trait CodegenShaderEntryPoint {
 
 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"));
+		match self {
+			ShaderNodeType::GpuNode => (),
+			_ => {
+				if parsed.is_async {
+					return Err(Error::new_spanned(&parsed.fn_name, "Shader nodes must not be async"));
+				}
+			}
 		}
 
 		match self {
+			ShaderNodeType::GpuNode => Ok(TokenStream::new()),
 			ShaderNodeType::PerPixelAdjust(x) => x.codegen_shader_entry_point(parsed),
 		}
 	}
 
 	fn codegen_gpu_node(&self, parsed: &ParsedNodeFn) -> syn::Result<TokenStream> {
 		match self {
+			ShaderNodeType::GpuNode => Ok(TokenStream::new()),
 			ShaderNodeType::PerPixelAdjust(x) => x.codegen_gpu_node(parsed),
 		}
 	}

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

@@ -1,11 +1,12 @@
 use crate::parsing::{Input, NodeFnAttributes, ParsedField, ParsedFieldType, ParsedNodeFn, RegularParsedField};
-use crate::shader_nodes::CodegenShaderEntryPoint;
+use crate::shader_nodes::{CodegenShaderEntryPoint, ShaderNodeType};
 use convert_case::{Case, Casing};
-use proc_macro2::{Ident, TokenStream};
+use proc_macro2::{Ident, Span, TokenStream};
 use quote::{ToTokens, format_ident, quote};
 use std::borrow::Cow;
 use syn::parse::{Parse, ParseStream};
-use syn::{Path, Type, TypePath};
+use syn::punctuated::Punctuated;
+use syn::{Path, Token, TraitBound, TraitBoundModifier, Type, TypeImplTrait, TypeParamBound};
 
 #[derive(Debug, Clone)]
 pub struct PerPixelAdjust {}
@@ -115,12 +116,16 @@ impl CodegenShaderEntryPoint for PerPixelAdjust {
 				ParsedFieldType::Node { .. } => Err(syn::Error::new_spanned(&f.pat_ident, "PerPixelAdjust shader nodes cannot accept other nodes as generics")),
 			})
 			.collect::<syn::Result<_>>()?;
-		let body = quote! {};
+		let body = quote! {
+			{
+
+			}
+		};
 
 		crate::codegen::generate_node_code(&ParsedNodeFn {
 			vis: parsed.vis.clone(),
 			attributes: NodeFnAttributes {
-				shader_node: None,
+				shader_node: Some(ShaderNodeType::GpuNode),
 				..parsed.attributes.clone()
 			},
 			fn_name,
@@ -130,9 +135,14 @@ impl CodegenShaderEntryPoint for PerPixelAdjust {
 			where_clause: None,
 			input: Input {
 				pat_ident: parsed.input.pat_ident.clone(),
-				ty: Type::Path(TypePath {
-					path: Path::from(format_ident!("Ctx")),
-					qself: None,
+				ty: Type::ImplTrait(TypeImplTrait {
+					impl_token: Token![impl](Span::call_site()),
+					bounds: Punctuated::from_iter([TypeParamBound::Trait(TraitBound {
+						paren_token: None,
+						modifier: TraitBoundModifier::None,
+						lifetimes: None,
+						path: Path::from(format_ident!("Ctx")),
+					})]),
 				}),
 				implementations: Default::default(),
 			},