Add workaround for cache context nullification breaking nested loop indexes (#3178)

* Disable caching for the instance repeat etc. nodes

* Add usize implementation for caching and monitor nodes

* Change return type of instance index node back to f64

* Cleanup while loop

* Remove stray usize changes

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

Author: TrueDoctor

node-graph/gcore/src/context.rs

@@ -27,7 +27,7 @@ pub trait ExtractAnimationTime {
 }
 
 pub trait ExtractIndex {
-	fn try_index(&self) -> Option<Vec<usize>>;
+	fn try_index(&self) -> Option<impl Iterator<Item = usize>>;
 }
 
 // Consider returning a slice or something like that
@@ -175,7 +175,7 @@ impl<T: ExtractAnimationTime + Sync> ExtractAnimationTime for Option<T> {
 	}
 }
 impl<T: ExtractIndex> ExtractIndex for Option<T> {
-	fn try_index(&self) -> Option<Vec<usize>> {
+	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		self.as_ref().and_then(|x| x.try_index())
 	}
 }
@@ -212,7 +212,7 @@ impl<T: ExtractAnimationTime + Sync> ExtractAnimationTime for Arc<T> {
 	}
 }
 impl<T: ExtractIndex> ExtractIndex for Arc<T> {
-	fn try_index(&self) -> Option<Vec<usize>> {
+	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		(**self).try_index()
 	}
 }
@@ -268,8 +268,8 @@ impl ExtractRealTime for ContextImpl<'_> {
 	}
 }
 impl ExtractIndex for ContextImpl<'_> {
-	fn try_index(&self) -> Option<Vec<usize>> {
-		self.index.clone()
+	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
+		self.index.clone().map(|x| x.into_iter())
 	}
 }
 impl ExtractVarArgs for ContextImpl<'_> {
@@ -304,8 +304,8 @@ impl ExtractAnimationTime for OwnedContextImpl {
 	}
 }
 impl ExtractIndex for OwnedContextImpl {
-	fn try_index(&self) -> Option<Vec<usize>> {
-		self.index.clone()
+	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
+		self.index.clone().map(|x| x.into_iter())
 	}
 }
 impl ExtractVarArgs for OwnedContextImpl {
@@ -418,7 +418,7 @@ impl OwnedContextImpl {
 			footprint,
 			varargs: None,
 			parent,
-			index,
+			index: index.map(|x| x.collect()),
 			real_time,
 			animation_time,
 		}

node-graph/gcore/src/vector/algorithms/instance.rs

@@ -2,7 +2,7 @@ use crate::gradient::GradientStops;
 use crate::raster_types::{CPU, Raster};
 use crate::table::{Table, TableRowRef};
 use crate::vector::Vector;
-use crate::{CloneVarArgs, Context, Ctx, ExtractAll, ExtractIndex, ExtractVarArgs, Graphic, InjectIndex, InjectVarArgs, OwnedContextImpl};
+use crate::{CloneVarArgs, Context, Ctx, ExtractAll, ExtractIndex, ExtractVarArgs, Graphic, InjectVarArgs, OwnedContextImpl};
 use glam::DVec2;
 use graphene_core_shaders::color::Color;
 
@@ -19,7 +19,7 @@ impl std::hash::Hash for HashableDVec2 {
 
 #[node_macro::node(name("Instance on Points"), category("Instancing"), path(graphene_core::vector))]
 async fn instance_on_points<T: Into<Graphic> + Default + Send + Clone + 'static>(
-	ctx: impl ExtractAll + CloneVarArgs + Sync + Ctx + InjectIndex + InjectVarArgs,
+	ctx: impl ExtractAll + CloneVarArgs + Sync + Ctx + InjectVarArgs,
 	points: Table<Vector>,
 	#[implementations(
 		Context -> Table<Graphic>,
@@ -63,7 +63,7 @@ async fn instance_on_points<T: Into<Graphic> + Default + Send + Clone + 'static>
 
 #[node_macro::node(category("Instancing"), path(graphene_core::vector))]
 async fn instance_repeat<T: Into<Graphic> + Default + Send + Clone + 'static>(
-	ctx: impl ExtractAll + CloneVarArgs + Ctx + InjectIndex,
+	ctx: impl ExtractAll + CloneVarArgs + Ctx,
 	#[implementations(
 		Context -> Table<Graphic>,
 		Context -> Table<Vector>,
@@ -106,9 +106,15 @@ async fn instance_position(ctx: impl Ctx + ExtractVarArgs) -> DVec2 {
 // TODO: Make this return a u32 instead of an f64, but we ned to improve math-related compatibility with integer types first.
 #[node_macro::node(category("Instancing"), path(graphene_core::vector))]
 async fn instance_index(ctx: impl Ctx + ExtractIndex, _primary: (), loop_level: u32) -> f64 {
-	ctx.try_index()
-		.and_then(|indexes| indexes.get(indexes.len().wrapping_sub(1).wrapping_sub(loop_level as usize)).copied())
-		.unwrap_or_default() as f64
+	let Some(index_iter) = ctx.try_index() else { return 0. };
+	let mut last = 0;
+	for (i, index) in index_iter.enumerate() {
+		if i == loop_level as usize {
+			return index as f64;
+		}
+		last = index;
+	}
+	last as f64
 }
 
 #[cfg(test)]