Function auto_tangents

node-graph/nodes/vector/src/vector_nodes.rs:994–1145

(
	_: impl Ctx,
	source: List<Vector>,
	/// The amount of spread for the auto-tangents, from 0 (sharp corner) to 1 (full spread).
	#[default(0.5)]
	#[range]
	#[soft(0..1)]
	spread: f64,
	/// If active

/// Automatically constructs tangents (Bézier handles) for anchor points in a vector path.
#[node_macro::node(category("Vector: Modifier"), name("Auto-Tangents"), path(core_types::vector))]
async fn auto_tangents(
	_: impl Ctx,
	source: List<Vector>,
	/// The amount of spread for the auto-tangents, from 0 (sharp corner) to 1 (full spread).
	#[default(0.5)]
	#[range]
	#[soft(0..1)]
	spread: f64,
	/// If active, existing non-zero handles won't be affected.
	#[default(true)]
	preserve_existing: bool,
) -> List<Vector> {
	(0..source.len())
		.map(|index| {
			let transform: DAffine2 = source.attribute_cloned_or_default(ATTR_TRANSFORM, index);
			let attributes = source.clone_item_attributes(index);
			let source = source.element(index).unwrap();

			let mut result = Vector {
				stroke: source.stroke.clone(),
				..Default::default()
			};

			for mut subpath in source.stroke_bezier_paths() {
				subpath.apply_transform(transform);

				let manipulators_list = subpath.manipulator_groups();
				if manipulators_list.len() < 2 {
					// Not enough points for softening or handle removal
					result.append_subpath(subpath, true);
					continue;
				}

				let mut new_manipulators_list = Vec::with_capacity(manipulators_list.len());
				// Track which manipulator indices were given auto-tangent (colinear) handles
				let mut auto_tangented = vec![false; manipulators_list.len()];
				let is_closed = subpath.closed();

				for i in 0..manipulators_list.len() {
					let current = &manipulators_list[i];
					let is_endpoint = !is_closed && (i == 0 || i == manipulators_list.len() - 1);

					if preserve_existing {
						// Check if this point has handles that are meaningfully different from the anchor
						let has_handles = (current.in_handle.is_some() && !current.in_handle.unwrap().abs_diff_eq(current.anchor, 1e-5))
							|| (current.out_handle.is_some() && !current.out_handle.unwrap().abs_diff_eq(current.anchor, 1e-5));

						// If the point already has handles, keep it as is
						if has_handles {
							new_manipulators_list.push(*current);
							continue;
						}
					}

					// If spread is 0, remove handles for this point, making it a sharp corner
					if spread == 0. {
						new_manipulators_list.push(ManipulatorGroup {
							anchor: current.anchor,