Restructure project directories (#333)

`/client/web` -> `/frontend`
`/client/cli` -> *delete for now*
`/client/native` -> *delete for now*
`/core/editor` -> `/editor`
`/core/document` -> `/graphene`
`/core/renderer` -> `/charcoal`
`/core/proc-macro` -> `/proc-macros` *(now plural)*

graphene/src/intersection.rs

@@ -0,0 +1,80 @@
+use std::ops::Mul;
+
+use glam::{DAffine2, DVec2};
+use kurbo::{BezPath, Line, PathSeg, Point, Shape, Vec2};
+
+#[derive(Debug, Clone, Default, Copy)]
+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]])
+	}
+
+	pub fn lines(&self) -> [Line; 4] {
+		[
+			Line::new(to_point(self.0[0]), to_point(self.0[1])),
+			Line::new(to_point(self.0[1]), to_point(self.0[2])),
+			Line::new(to_point(self.0[2]), to_point(self.0[3])),
+			Line::new(to_point(self.0[3]), to_point(self.0[0])),
+		]
+	}
+}
+
+impl Mul<Quad> for DAffine2 {
+	type Output = Quad;
+
+	fn mul(self, rhs: Quad) -> Self::Output {
+		let mut output = Quad::default();
+		for (i, point) in rhs.0.iter().enumerate() {
+			output.0[i] = self.transform_point2(*point);
+		}
+		output
+	}
+}
+
+fn to_point(vec: DVec2) -> Point {
+	Point::new(vec.x, vec.y)
+}
+
+pub fn intersect_quad_bez_path(quad: Quad, shape: &BezPath, closed: bool) -> bool {
+	// check if outlines intersect
+	if shape.segments().any(|path_segment| quad.lines().iter().any(|line| !path_segment.intersect_line(*line).is_empty())) {
+		return true;
+	}
+	// check if selection is entirely within the shape
+	if closed && quad.0.iter().any(|q| shape.contains(to_point(*q))) {
+		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
+}
+
+pub fn get_arbitrary_point_on_path(path: &BezPath) -> Option<Point> {
+	path.segments().next().map(|seg| match seg {
+		PathSeg::Line(line) => line.p0,
+		PathSeg::Quad(quad) => quad.p0,
+		PathSeg::Cubic(cubic) => cubic.p0,
+	})
+}