From cf3c8378557457363853d6795e4ddf9e70a4738e Mon Sep 17 00:00:00 2001
From: Arne Dußin
Date: Thu, 26 Nov 2020 20:50:30 +0100
Subject: Make polygons deletable

Before, the deletion tool was not targeting polygons. I also took the
liberty to broaden the functionality of the surface trait, which now can
check if a rectangle or polygon is contained.
---
 src/math/polygon/mod.rs | 50 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

(limited to 'src/math/polygon')

diff --git a/src/math/polygon/mod.rs b/src/math/polygon/mod.rs
index ed48751..c9dad91 100644
--- a/src/math/polygon/mod.rs
+++ b/src/math/polygon/mod.rs
@@ -6,7 +6,7 @@ pub mod triangulate;
 pub use polygon_graph::*;
 pub use triangulate::*;
 
-use super::{LineSegment, Surface, TripletOrientation, Vec2};
+use super::{LineSegment, Rect, Surface, TripletOrientation, Vec2};
 use crate::math;
 use nalgebra::{ClosedDiv, ClosedMul, ClosedSub, RealField, Scalar};
 use num_traits::Zero;
@@ -361,6 +361,54 @@ impl<
 
         true
     }
+
+    fn contains_rect(&self, rect: &Rect<T>) -> bool {
+        /* Turn the rectangle into a vector with its hull line segments. If all hull segments are
+         * contained in the polygon, the rectangle is contained completely.
+         */
+        let hull_edges = [
+            // Top left to bottom left.
+            LineSegment::new(
+                Vec2::new(rect.x, rect.y),
+                Vec2::new(rect.x, rect.y + rect.h),
+            ),
+            // Bottom left to bottom right.
+            LineSegment::new(
+                Vec2::new(rect.x, rect.y + rect.h),
+                Vec2::new(rect.x + rect.w, rect.y + rect.h),
+            ),
+            // Bottom right to top right.
+            LineSegment::new(
+                Vec2::new(rect.x + rect.w, rect.y + rect.h),
+                Vec2::new(rect.x + rect.w, rect.y),
+            ),
+            // Top right to top left.
+            LineSegment::new(
+                Vec2::new(rect.x + rect.w, rect.y),
+                Vec2::new(rect.x, rect.y),
+            ),
+        ];
+
+        hull_edges
+            .iter()
+            .all(|edge| self.contains_line_segment(edge))
+    }
+
+    fn contains_polygon(&self, polygon: &Polygon<T>) -> bool {
+        /* Check for all edges of the polygon that they are contained by the polygon. If they all
+         * are, then the polygon itself must also be contained.
+         */
+        for i in 0..polygon.corners.len() {
+            let next = (i + 1) % polygon.corners.len();
+            if !self
+                .contains_line_segment(&LineSegment::new(polygon.corners[i], polygon.corners[next]))
+            {
+                return false;
+            }
+        }
+
+        true
+    }
 }
 
 /* Helper function to calculate the combined angle of a set of points when connecting them one
-- 
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