Add snapping for a line's midpoint when it's being drawn

editor/src/messages/portfolio/document/utility_types/network_interface.rs

@@ -4198,7 +4198,6 @@ impl NodeNetworkInterface {
 					let Some(downstream_nodes) = outward_wires.get(&current_node) else { continue };
 					for downstream_node in downstream_nodes {
 						if let InputConnector::Node { node_id: downstream_id, .. } = downstream_node {
-							let downstream_node_output = OutputConnector::node(*downstream_id, 0);
 							if !delete_nodes.contains(downstream_id) {
 								can_delete = false;
 								break;

editor/src/messages/tool/tool_messages/line_tool.rs

@@ -394,6 +394,7 @@ fn generate_line(tool_data: &mut LineToolData, snap_data: SnapData, lock_angle:
 
 	let near_point = SnapCandidatePoint::handle_neighbors(document_points[1], [tool_data.drag_start]);
 	let far_point = SnapCandidatePoint::handle_neighbors(2. * document_points[0] - document_points[1], [tool_data.drag_start]);
+	let mid_point = SnapCandidatePoint::handle_neighbors((tool_data.drag_start + document_points[1]) / 2., [tool_data.drag_start]);
 	let config = SnapTypeConfiguration::default();
 
 	if constrained {
@@ -410,8 +411,15 @@ fn generate_line(tool_data: &mut LineToolData, snap_data: SnapData, lock_angle:
 			snap.update_indicator(best);
 		} else {
 			let snapped = snap.constrained_snap(&snap_data, &near_point, constraint, config);
-			document_points[1] = snapped.snapped_point_document;
-			snap.update_indicator(snapped);
+			let snapped_mid = snap.constrained_snap(&snap_data, &mid_point, constraint, config);
+			let best = if snap_data.document.snapping_state.path.line_midpoint && snapped_mid.other_snap_better(&snapped_mid) {
+				document_points[1] += (snapped_mid.snapped_point_document - mid_point.document_point) * 2.;
+				snapped_mid
+			} else {
+				document_points[1] = snapped.snapped_point_document;
+				snapped.clone()
+			};
+			snap.update_indicator(best);
 		}
 	} else if center {
 		let snapped = snap.free_snap(&snap_data, &near_point, config);
@@ -422,8 +430,15 @@ fn generate_line(tool_data: &mut LineToolData, snap_data: SnapData, lock_angle:
 		snap.update_indicator(best);
 	} else {
 		let snapped = snap.free_snap(&snap_data, &near_point, config);
-		document_points[1] = snapped.snapped_point_document;
-		snap.update_indicator(snapped);
+		let snapped_mid = snap.free_snap(&snap_data, &mid_point, config);
+		let best = if snap_data.document.snapping_state.path.line_midpoint && snapped_mid.other_snap_better(&snapped_mid) {
+			document_points[1] += (snapped_mid.snapped_point_document - mid_point.document_point) * 2.;
+			snapped_mid
+		} else {
+			document_points[1] = snapped.snapped_point_document;
+			snapped.clone()
+		};
+		snap.update_indicator(best);
 	}
 
 	// Snapping happens in other space, while document graph renders in another.
@@ -433,7 +448,8 @@ fn generate_line(tool_data: &mut LineToolData, snap_data: SnapData, lock_angle:
 #[cfg(test)]
 mod test_line_tool {
 	use crate::messages::portfolio::document::graph_operation::utility_types::TransformIn;
-	use crate::{messages::tool::common_functionality::graph_modification_utils::NodeGraphLayer, test_utils::test_prelude::*};
+	use crate::messages::tool::common_functionality::graph_modification_utils::NodeGraphLayer;
+	use crate::test_utils::test_prelude::*;
 	use glam::DAffine2;
 	use graph_craft::document::value::TaggedValue;