Add "Perpendicular to Endpoint" snapping target (#2581)

* Perpendicular snap for line's endpoints

* move comment

* Code review

---------

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

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

@@ -99,6 +99,7 @@ impl SnappingState {
 				PathSnapTarget::NormalToPath => self.path.normal_to_path,
 				PathSnapTarget::TangentToPath => self.path.tangent_to_path,
 				PathSnapTarget::IntersectionPoint => self.path.path_intersection_point,
+				PathSnapTarget::PerpendicularToEndpoint => self.path.perpendicular_from_endpoint,
 			},
 			SnapTarget::Artboard(_) => self.artboards,
 			SnapTarget::Grid(_) => self.grid_snapping,
@@ -142,6 +143,7 @@ pub struct PathSnapping {
 	pub tangent_to_path: bool,
 	pub path_intersection_point: bool,
 	pub align_with_anchor_point: bool, // TODO: Rename
+	pub perpendicular_from_endpoint: bool,
 }
 
 impl Default for PathSnapping {
@@ -154,6 +156,7 @@ impl Default for PathSnapping {
 			tangent_to_path: true,
 			path_intersection_point: true,
 			align_with_anchor_point: true,
+			perpendicular_from_endpoint: true,
 		}
 	}
 }
@@ -476,6 +479,7 @@ pub enum PathSnapTarget {
 	NormalToPath,
 	TangentToPath,
 	IntersectionPoint,
+	PerpendicularToEndpoint,
 }
 
 impl fmt::Display for PathSnapTarget {
@@ -487,6 +491,7 @@ impl fmt::Display for PathSnapTarget {
 			PathSnapTarget::NormalToPath => write!(f, "Path: Normal to Path"),
 			PathSnapTarget::TangentToPath => write!(f, "Path: Tangent to Path"),
 			PathSnapTarget::IntersectionPoint => write!(f, "Path: Intersection Point"),
+			PathSnapTarget::PerpendicularToEndpoint => write!(f, "Path: Perp. to Endpoint"),
 		}
 	}
 }
@@ -533,6 +538,7 @@ pub enum AlignmentSnapTarget {
 	ArtboardCenterPoint,
 	AlignWithAnchorPoint,
 	IntersectionPoint,
+	PerpendicularToEndpoint,
 }
 
 impl fmt::Display for AlignmentSnapTarget {
@@ -544,6 +550,7 @@ impl fmt::Display for AlignmentSnapTarget {
 			AlignmentSnapTarget::ArtboardCenterPoint => write!(f, "{}", ArtboardSnapTarget::CenterPoint),
 			AlignmentSnapTarget::AlignWithAnchorPoint => write!(f, "{}", PathSnapTarget::AnchorPointWithColinearHandles),
 			AlignmentSnapTarget::IntersectionPoint => write!(f, "{}", PathSnapTarget::IntersectionPoint),
+			AlignmentSnapTarget::PerpendicularToEndpoint => write!(f, "{}", PathSnapTarget::PerpendicularToEndpoint),
 		}
 	}
 }

editor/src/messages/tool/common_functionality/snapping/alignment_snapper.rs

@@ -59,13 +59,46 @@ impl AlignmentSnapper {
 		// TODO: snap handle points
 		let document = snap_data.document;
 		let tolerance = snap_tolerance(document);
-
+		let tolerance_squared = tolerance.powi(2);
 		let mut snap_x: Option<SnappedPoint> = None;
 		let mut snap_y: Option<SnappedPoint> = None;
 
 		for target_point in self.bounding_box_points.iter().chain(unselected_geometry) {
 			let target_position = target_point.document_point;
 
+			// Perpendicular snap for line's endpoints
+			if let Some(quad) = target_point.quad.map(|q| q.0) {
+				if quad[0] == quad[3] && quad[1] == quad[2] && quad[0] == target_point.document_point {
+					let [p1, p2, ..] = quad;
+					let direction = (p2 - p1).normalize();
+					let normal = DVec2::new(-direction.y, direction.x);
+
+					for endpoint in [p1, p2] {
+						if let Some(perpendicular_snap) = Quad::intersect_rays(point.document_point, direction, endpoint, normal) {
+							let distance_squared = point.document_point.distance_squared(perpendicular_snap);
+							if distance_squared < tolerance_squared {
+								let distance = distance_squared.sqrt();
+								let distance_to_align_target = perpendicular_snap.distance_squared(endpoint).sqrt();
+
+								let snap_point = SnappedPoint {
+									snapped_point_document: perpendicular_snap,
+									source: point.source,
+									target: SnapTarget::Alignment(AlignmentSnapTarget::PerpendicularToEndpoint),
+									target_bounds: Some(Quad(quad)),
+									distance,
+									tolerance,
+									distance_to_align_target,
+									fully_constrained: false,
+									at_intersection: true,
+									alignment_target_x: Some(endpoint),
+									..Default::default()
+								};
+								snap_results.points.push(snap_point);
+							}
+						}
+					}
+				}
+			}
 			let [point_on_x, point_on_y] = if let SnapConstraint::Line { origin, direction } = constraint {
 				[
 					Quad::intersect_rays(target_point.document_point, DVec2::Y, origin, direction),