From 23c14642b1d93905ab9bc86ca821183dd4a97f8c Mon Sep 17 00:00:00 2001
From: Dennis Kobert <d-kobert@web.de>
Date: Sun, 2 Jun 2019 11:34:51 +0200
Subject: Rework collision detection to use projection

---
 game_server/src/collide.rs | 113 ++++++++++++++++++++++++++++++---------------
 1 file changed, 76 insertions(+), 37 deletions(-)

(limited to 'game_server/src/collide.rs')

diff --git a/game_server/src/collide.rs b/game_server/src/collide.rs
index 7439101..d510a04 100644
--- a/game_server/src/collide.rs
+++ b/game_server/src/collide.rs
@@ -18,54 +18,31 @@ impl Collide<Vec2> for AABox {
 
 impl Collide<AABox> for AABox {
     fn collides(&self, other: &Self) -> bool {
-        self.collides(&other.pos)
-        || self.collides(&(other.pos + Vec2{x: other.size.x, y: 0.0}))
-        || self.collides(&(other.pos + Vec2{x: 0.0, y: other.size.y}))
-        || self.collides(&(other.pos + other.size))
-
-        || other.collides(&(self.pos))
-        || other.collides(&(self.pos + Vec2{x: self.size.x, y: 0.0}))
-        || other.collides(&(self.pos + Vec2{x: 0.0, y: self.size.y}))
-        || other.collides(&(self.pos + self.size))
+        self.pos.x < other.pos.x + other.size.x && other.pos.x < self.pos.x + self.size.x
+        && self.pos.y < other.pos.y + other.size.y && other.pos.y < self.pos.y + self.size.y
     }
 }
 
 impl Collide<Vec2> for RBox {
     fn collides(&self, other: &Vec2) -> bool {
+        let v1_diff = *other + self.v1 * (-self.v1.scalar(&other) / self.v1.distance2());
+        let v2_diff = *other + self.v2 * (-self.v2.scalar(&other) / self.v2.distance2());
 
-        let da = self.size.norm();
-        let dax = other.x - self.pos.x;
-        let day = other.y - self.pos.y;
-        
-        let dot = dax * da.x + day * da.y;
-        let px = self.pos.x + da.x * dot;
-        let py = self.pos.y + da.y * dot;
-       
-        let p = Vec2{x: px, y: py};
-        if !(self.pos < p && p < self.pos + self.size) {
-            return false; 
-        } 
-
-        let ddx = other.x-px; 
-        let ddy = other.y-py;
-        let manhattenDistance = ddx + ddy;
-
-        manhattenDistance < self.w 
+        self.pos < v1_diff && v1_diff < self.pos + self.v2
+        && self.pos < v2_diff && v2_diff < self.pos + self.v1
     }
 }
 
 impl Collide<AABox> for RBox {
     fn collides(&self, other: &AABox) -> bool {
-        self.collides(&other.pos)
-        || self.collides(&(other.pos + Vec2{x: other.size.x, y: 0.0}))
-        || self.collides(&(other.pos + Vec2{x: 0.0, y: other.size.y}))
-        || self.collides(&(other.pos + other.size))
-
-        || other.collides(&(self.pos))
-        || other.collides(&(self.pos + Vec2{x: self.size.x, y: 0.0}))
-        || other.collides(&(self.pos + Vec2{x: 0.0, y: self.size.y}))
-        || other.collides(&(self.pos + self.size))
-        
+        let v1_diff = other.pos + self.v1 * (-self.v1.scalar(&other.pos) / self.v1.distance2());
+        let v2_diff = other.pos + self.v2 * (-self.v2.scalar(&other.pos) / self.v2.distance2());
+        let other_size = other.pos + other.size;
+        let v1_diff_size = other_size + self.v1 * (-self.v1.scalar(&other_size) / self.v1.distance2());
+        let v2_diff_size = other_size + self.v2 * (-self.v2.scalar(&other_size) / self.v2.distance2());
+
+        self.pos < v1_diff + other.size && v1_diff < self.pos + self.v2
+        && self.pos < v2_diff + other.size && v2_diff < self.pos + self.v1
     }
 }
 
@@ -74,3 +51,65 @@ impl<S, T: Collide<S>> Collide<S> for Vec<T> {
         self.iter().any(|x| x.collides(other))
     }
 }
+
+#[cfg(test)]
+    mod tests {
+        use super::*;
+        
+        #[test]
+        fn test_collide_dot_dot() {
+             let a = Vec2{x: 1.0, y: 7.5};
+             assert!(a.collides(&a));
+        }
+    
+        #[test]
+        fn test_not_collide_dot_dot() {
+             let a = Vec2{x: 1.0, y: 7.5};
+             let b = Vec2{x: 5.0, y: 7.5};
+             assert!(!a.collides(&b));
+        }
+
+        #[test]
+        fn test_collide_aabox_dot() {
+             let a = Vec2{x: 1.0, y: 2.5};
+             let b = Vec2{x: 3.0, y: 7.5};
+             let c = Vec2{x: 1.5, y: 5.0};
+             let aa_box = AABox{pos: a, size: b};
+
+             assert!(aa_box.collides(&c));
+        }
+    
+        #[test]
+        fn test_not_collide_aabox_aabox() {
+             let a = Vec2{x: 1.0, y: 7.5};
+             let b = Vec2{x: 3.0, y: 2.5};
+             let c = Vec2{x: 0.5, y: 5.0};
+             let aa_box = AABox{pos: a, size: b};
+             let a = Vec2{x: 1.0, y: 7.5};
+             let b = Vec2{x: 3.0, y: 2.5};
+             let c = Vec2{x: 0.5, y: 5.0};
+             let aa_box = AABox{pos: a, size: b};
+
+             assert!(!(aa_box.collides(&c)));
+        }
+
+        #[test]
+        fn test_collide_Rbox_dot() {
+             let a = Vec2{x: 1.0, y: 2.5};
+             let b = Vec2{x: 3.0, y: 7.5};
+             let c = Vec2{x: 1.5, y: 5.0};
+             let aa_box = AABox{pos: a, size: b};
+
+             assert!(aa_box.collides(&c));
+        }
+    
+        #[test]
+        fn test_not_collide_Rbox_dot() {
+             let a = Vec2{x: 1.0, y: 7.5};
+             let b = Vec2{x: 3.0, y: 2.5};
+             let c = Vec2{x: 0.5, y: 5.0};
+             let aa_box = AABox{pos: a, size: b};
+
+             assert!(!(aa_box.collides(&c)));
+        }
+}
-- 
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