New node: Merge by Distance

node-graph/gcore/Cargo.toml

@@ -28,10 +28,7 @@ std = [
 	"image",
 	"reflections",
 ]
-reflections = [
-	"alloc",
-	"ctor",
-]
+reflections = ["alloc", "ctor"]
 serde = [
 	"dep:serde",
 	"glam/serde",
@@ -67,7 +64,7 @@ rand_chacha = { workspace = true, optional = true }
 bezier-rs = { workspace = true, optional = true }
 kurbo = { workspace = true, optional = true }
 base64 = { workspace = true, optional = true }
-vello = { workspace  = true, optional = true }
+vello = { workspace = true, optional = true }
 wgpu = { workspace = true, optional = true }
 specta = { workspace = true, optional = true }
 rustybuzz = { workspace = true, optional = true }
@@ -80,6 +77,8 @@ image = { workspace = true, optional = true, default-features = false, features
 	"png",
 ] }
 math-parser = { path = "../../libraries/math-parser" }
+rustc-hash = { workspace = true }
+petgraph = "0.7.1"
 
 [dev-dependencies]
 # Workspace dependencies

node-graph/gcore/src/vector/merge_by_distance.rs

@@ -0,0 +1,109 @@
+//! Collapse all nodes with all edges < distance
+
+use glam::DVec2;
+use petgraph::prelude::UnGraphMap;
+use rustc_hash::FxHashSet;
+
+use super::PointId;
+use super::VectorData;
+
+use super::VectorDataIndex;
+
+impl VectorData {
+	/// Collapse all nodes with all edges < distance
+	pub(crate) fn merge_by_distance(&mut self, distance: f64) {
+		// treat self as an undirected graph with point = node, and segment = edge
+		let indices = VectorDataIndex::build_from(self);
+
+		// Graph that will contain only short edges. References data graph
+		let mut short_edges = UnGraphMap::new();
+		for seg_id in self.segment_ids().iter().copied() {
+			let length = indices.segment_chord_length(seg_id);
+			if length < distance {
+				let [start, end] = indices.segment_ends(seg_id);
+				let start = indices.point_graph.node_weight(start).unwrap().id;
+				let end = indices.point_graph.node_weight(end).unwrap().id;
+
+				short_edges.add_node(start);
+				short_edges.add_node(end);
+				short_edges.add_edge(start, end, seg_id);
+			}
+		}
+
+		// Now group connected segments - all will be collapsed to a single point.
+		// Note: there are a few algos for this - perhaps test empirically to find fastest
+		let collapse: Vec<FxHashSet<PointId>> = petgraph::algo::tarjan_scc(&short_edges).into_iter().map(|connected| connected.into_iter().collect()).collect();
+		let average_position = collapse
+			.iter()
+			.map(|collapse_set| {
+				let sum: DVec2 = collapse_set.iter().map(|&id| indices.point_position(id, self)).sum();
+				sum / collapse_set.len() as f64
+			})
+			.collect::<Vec<_>>();
+
+		// we collect all points up and delete them at the end, so that our indices aren't invalidated
+		let mut points_to_delete = FxHashSet::default();
+		let mut segments_to_delete = FxHashSet::default();
+		for (mut collapse_set, average_pos) in collapse.into_iter().zip(average_position.into_iter()) {
+			// remove any segments where both endpoints are in the collapse set
+			segments_to_delete.extend(self.segment_domain.iter().filter_map(|(id, start_offset, end_offset, _)| {
+				let start = self.point_domain.ids()[start_offset];
+				let end = self.point_domain.ids()[end_offset];
+				if collapse_set.contains(&start) && collapse_set.contains(&end) {
+					Some(id)
+				} else {
+					None
+				}
+			}));
+
+			// Delete all points but the first (arbitrary). Set that point's position to the
+			// average of the points, update segments to use replace all points with collapsed
+			// point.
+
+			// Unwrap: set created from connected algo will not be empty
+			let first_id = collapse_set.iter().copied().next().unwrap();
+			// `first_id` the point we will collapse to.
+			collapse_set.remove(&first_id);
+			let first_offset = indices.point_to_offset[&first_id];
+
+			// look for segments with ends in collapse_set and replace them with the point we are collapsing to
+			for (_, start_offset, end_offset, handles) in self.segment_domain.iter_mut() {
+				let start_id = self.point_domain.ids()[*start_offset];
+				let end_id = self.point_domain.ids()[*end_offset];
+
+				// moved points (only need to update Bezier handles)
+				if start_id == first_id {
+					let point_position = self.point_domain.positions[*start_offset];
+					handles.move_start(average_pos - point_position);
+				}
+				if end_id == first_id {
+					let point_position = self.point_domain.positions[*end_offset];
+					handles.move_end(average_pos - point_position);
+				}
+
+				// removed points
+				if collapse_set.contains(&start_id) {
+					let point_position = self.point_domain.positions[*start_offset];
+					*start_offset = first_offset;
+					handles.move_start(average_pos - point_position);
+				}
+				if collapse_set.contains(&end_id) {
+					let point_position = self.point_domain.positions[*end_offset];
+					*end_offset = first_offset;
+					handles.move_end(average_pos - point_position);
+				}
+			}
+			// This must come after iterating segments, so segments involving the point at
+			// `first_offset` have their handles updated correctly.
+			self.point_domain.positions[first_offset] = average_pos;
+
+			points_to_delete.extend(collapse_set)
+		}
+		self.segment_domain.retain(|id| !segments_to_delete.contains(id), usize::MAX);
+		self.point_domain.retain(&mut self.segment_domain, |id| !points_to_delete.contains(id));
+
+		log::debug!("{:?}", self.segment_domain.handles());
+
+		// TODO: don't forget about faces
+	}
+}

node-graph/gcore/src/vector/mod.rs

@@ -12,3 +12,5 @@ mod vector_nodes;
 pub use vector_nodes::*;
 
 pub use bezier_rs;
+
+mod merge_by_distance;

node-graph/gcore/src/vector/vector_data.rs

@@ -1,6 +1,9 @@
 mod attributes;
+mod indexed;
 mod modification;
+
 pub use attributes::*;
+pub use indexed::VectorDataIndex;
 pub use modification::*;
 
 use super::style::{PathStyle, Stroke};
@@ -12,6 +15,7 @@ use dyn_any::DynAny;
 
 use core::borrow::Borrow;
 use glam::{DAffine2, DVec2};
+use std::borrow::Cow;
 
 // TODO: Eventually remove this migration document upgrade code
 pub fn migrate_vector_data<'de, D: serde::Deserializer<'de>>(deserializer: D) -> Result<VectorDataTable, D::Error> {
@@ -35,6 +39,8 @@ pub type VectorDataTable = Instances<VectorData>;
 
 /// [VectorData] is passed between nodes.
 /// It contains a list of subpaths (that may be open or closed), a transform, and some style information.
+///
+/// Segments are connected if they share end points.
 #[derive(Clone, Debug, PartialEq, DynAny)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct VectorData {
@@ -65,6 +71,24 @@ impl core::hash::Hash for VectorData {
 	}
 }
 
+impl<'a> From<&'a VectorData> for Cow<'a, VectorData> {
+	fn from(value: &'a VectorData) -> Self {
+		Self::Borrowed(value)
+	}
+}
+
+impl<'a> From<&'a mut VectorData> for Cow<'a, VectorData> {
+	fn from(value: &'a mut VectorData) -> Self {
+		Self::Borrowed(value)
+	}
+}
+
+impl From<VectorData> for Cow<'static, VectorData> {
+	fn from(value: VectorData) -> Self {
+		Self::Owned(value)
+	}
+}
+
 impl VectorData {
 	/// An empty subpath with no data, an identity transform, and a black fill.
 	pub const fn empty() -> Self {
@@ -241,6 +265,13 @@ impl VectorData {
 		index.flat_map(|index| self.segment_domain.connected_points(index).map(|index| self.point_domain.ids()[index]))
 	}
 
+	/// A slice all segment IDs
+	///
+	/// Convenience function
+	pub fn segment_ids(&self) -> &[SegmentId] {
+		self.segment_domain.ids()
+	}
+
 	/// Enumerate all segments that start at the point.
 	pub fn start_connected(&self, point: PointId) -> impl Iterator<Item = SegmentId> + '_ {
 		let index = [self.point_domain.resolve_id(point)].into_iter().flatten();

node-graph/gcore/src/vector/vector_data/attributes.rs

@@ -1,8 +1,10 @@
 use crate::vector::vector_data::{HandleId, VectorData, VectorDataTable};
 use crate::vector::ConcatElement;
 
+use bezier_rs::BezierHandles;
 use dyn_any::DynAny;
 
+use core::iter::zip;
 use glam::{DAffine2, DVec2};
 use std::collections::HashMap;
 use std::hash::{Hash, Hasher};
@@ -82,7 +84,7 @@ impl core::hash::BuildHasher for NoHashBuilder {
 /// Stores data which is per-point. Each point is merely a position and can be used in a point cloud or to for a bézier path. In future this will be extendable at runtime with custom attributes.
 pub struct PointDomain {
 	id: Vec<PointId>,
-	positions: Vec<DVec2>,
+	pub(crate) positions: Vec<DVec2>,
 }
 
 impl core::hash::Hash for PointDomain {
@@ -117,7 +119,8 @@ impl PointDomain {
 				id_map.push(new_index);
 				new_index += 1;
 			} else {
-				id_map.push(usize::MAX); // A placeholder for invalid ids. This is checked after the segment domain is modified.
+				// A placeholder for invalid ids. This is checked after the segment domain is modified.
+				id_map.push(usize::MAX);
 			}
 		}
 
@@ -184,6 +187,11 @@ impl PointDomain {
 			*pos = transform.transform_point2(*pos);
 		}
 	}
+
+	/// Iterate over point IDs and positions
+	pub fn iter(&self) -> impl Iterator<Item = (PointId, DVec2)> + '_ {
+		self.ids().iter().copied().zip(self.positions().iter().copied())
+	}
 }
 
 #[derive(Clone, Debug, Default, PartialEq, Hash, DynAny)]
@@ -359,6 +367,7 @@ impl SegmentDomain {
 		})
 	}
 
+	/// Get index from ID, `O(n)`
 	fn id_to_index(&self, id: SegmentId) -> Option<usize> {
 		debug_assert_eq!(self.ids.len(), self.handles.len());
 		debug_assert_eq!(self.ids.len(), self.start_point.len());
@@ -413,11 +422,35 @@ impl SegmentDomain {
 	pub(crate) fn connected_count(&self, point: usize) -> usize {
 		self.all_connected(point).count()
 	}
+
+	/// Iterate over segments in the domain.
+	///
+	/// tuple is: (id, start point, end point, handles)
+	pub(crate) fn iter(&self) -> impl Iterator<Item = (SegmentId, usize, usize, BezierHandles)> + '_ {
+		let ids = self.ids.iter().copied();
+		let start_point = self.start_point.iter().copied();
+		let end_point = self.end_point.iter().copied();
+		let handles = self.handles.iter().copied();
+		zip(ids, zip(start_point, zip(end_point, handles))).map(|(id, (start_point, (end_point, handles)))| (id, start_point, end_point, handles))
+	}
+
+	/// Iterate over segments in the domain.
+	///
+	/// tuple is: (id, start point, end point, handles)
+	pub(crate) fn iter_mut(&mut self) -> impl Iterator<Item = (&mut SegmentId, &mut usize, &mut usize, &mut BezierHandles)> + '_ {
+		let ids = self.ids.iter_mut();
+		let start_point = self.start_point.iter_mut();
+		let end_point = self.end_point.iter_mut();
+		let handles = self.handles.iter_mut();
+		zip(ids, zip(start_point, zip(end_point, handles))).map(|(id, (start_point, (end_point, handles)))| (id, start_point, end_point, handles))
+	}
 }
 
 #[derive(Clone, Debug, Default, PartialEq, Hash, DynAny)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-/// Stores data which is per-region. A region is an enclosed area composed of a range of segments from the [`SegmentDomain`] that can be given a fill. In future this will be extendable at runtime with custom attributes.
+/// Stores data which is per-region. A region is an enclosed area composed of a range
+/// of segments from the [`SegmentDomain`] that can be given a fill. In future this will
+/// be extendable at runtime with custom attributes.
 pub struct RegionDomain {
 	ids: Vec<RegionId>,
 	segment_range: Vec<core::ops::RangeInclusive<SegmentId>>,
@@ -457,10 +490,6 @@ impl RegionDomain {
 		self.fill.push(fill);
 	}
 
-	fn _resolve_id(&self, id: RegionId) -> Option<usize> {
-		self.ids.iter().position(|&check_id| check_id == id)
-	}
-
 	pub fn next_id(&self) -> RegionId {
 		self.ids.iter().copied().max_by(|a, b| a.0.cmp(&b.0)).map(|mut id| id.next_id()).unwrap_or(RegionId::ZERO)
 	}