From 9cd6d57337af419917ebc267ecb5e1c3e20a9f9d Mon Sep 17 00:00:00 2001
From: Paul Kupper <11900073+pkupper@users.noreply.github.com>
Date: Wed, 11 Aug 2021 23:58:10 +0200
Subject: [PATCH] Fix n-gon intersection (#342)

* Fix n-gon intersection

* Fix not all layers selected with box selection

* Code golf for TrueDoctor
---
 Cargo.lock                   |  2 +-
 graphene/Cargo.toml          |  4 +++-
 graphene/src/intersection.rs | 41 ++++++++++++++----------------------
 3 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 2459b309d2..1c56b9a347 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -168,7 +168,7 @@ dependencies = [
 [[package]]
 name = "kurbo"
 version = "0.8.1"
-source = "git+https://github.com/linebender/kurbo#0ef68211223b956942c4a5834d66a2625cb8d575"
+source = "git+https://github.com/GraphiteEditor/kurbo.git#feb9ef74f841fcc5890bfe6ae763fbb986c80490"
 dependencies = [
  "arrayvec",
  "serde",
diff --git a/graphene/Cargo.toml b/graphene/Cargo.toml
index 019f056ee8..f6d8964ea8 100644
--- a/graphene/Cargo.toml
+++ b/graphene/Cargo.toml
@@ -11,6 +11,8 @@ license = "Apache-2.0"
 [dependencies]
 log = "0.4"
 
-kurbo = {git="https://github.com/linebender/kurbo", features = ["serde"]}
+kurbo = { git = "https://github.com/GraphiteEditor/kurbo.git", features = [
+    "serde",
+] }
 serde = { version = "1.0", features = ["derive"] }
 glam = { version = "0.17", features = ["serde"] }
diff --git a/graphene/src/intersection.rs b/graphene/src/intersection.rs
index ddbbfe53fa..c4a940ff74 100644
--- a/graphene/src/intersection.rs
+++ b/graphene/src/intersection.rs
@@ -1,7 +1,7 @@
 use std::ops::Mul;
 
 use glam::{DAffine2, DVec2};
-use kurbo::{BezPath, Line, PathSeg, Point, Shape, Vec2};
+use kurbo::{BezPath, Line, PathSeg, Point, Shape};
 
 #[derive(Debug, Clone, Default, Copy)]
 pub struct Quad([DVec2; 4]);
@@ -9,7 +9,7 @@ pub struct Quad([DVec2; 4]);
 impl Quad {
 	pub fn from_box(bbox: [DVec2; 2]) -> Self {
 		let size = bbox[1] - bbox[0];
-		Self([bbox[0], bbox[0] + size * DVec2::X, bbox[0] + size * DVec2::Y, bbox[1]])
+		Self([bbox[0], bbox[0] + size * DVec2::X, bbox[1], bbox[0] + size * DVec2::Y])
 	}
 
 	pub fn lines(&self) -> [Line; 4] {
@@ -20,6 +20,16 @@ impl Quad {
 			Line::new(to_point(self.0[3]), to_point(self.0[0])),
 		]
 	}
+
+	pub fn path(&self) -> BezPath {
+		let mut path = kurbo::BezPath::new();
+		path.move_to(to_point(self.0[0]));
+		path.line_to(to_point(self.0[1]));
+		path.line_to(to_point(self.0[2]));
+		path.line_to(to_point(self.0[3]));
+		path.close_path();
+		path
+	}
 }
 
 impl Mul<Quad> for DAffine2 {
@@ -44,31 +54,12 @@ pub fn intersect_quad_bez_path(quad: Quad, shape: &BezPath, closed: bool) -> boo
 		return true;
 	}
 	// check if selection is entirely within the shape
-	if closed && quad.0.iter().any(|q| shape.contains(to_point(*q))) {
+	if closed && shape.contains(to_point(quad.0[0])) {
 		return true;
 	}
-	// check if shape is entirely within the selection
-	if let Some(shape_point) = get_arbitrary_point_on_path(shape) {
-		let mut pos = 0;
-		let mut neg = 0;
-		for line in quad.lines() {
-			if line.p0 == shape_point {
-				return true;
-			};
-			let line_vec = Vec2::new(line.p1.x - line.p0.x, line.p1.y - line.p0.y);
-			let point_vec = Vec2::new(line.p1.x - shape_point.x, line.p1.y - shape_point.y);
-			let cross = line_vec.cross(point_vec);
-			if cross > 0.0 {
-				pos += 1;
-			} else if cross < 0.0 {
-				neg += 1;
-			}
-			if pos > 0 && neg > 0 {
-				return false;
-			}
-		}
-	}
-	true
+
+	// check if shape is entirely within selection
+	get_arbitrary_point_on_path(shape).map(|shape_point| quad.path().contains(shape_point)).unwrap_or_default()
 }
 
 pub fn get_arbitrary_point_on_path(path: &BezPath) -> Option<Point> {