--- a/rust/hwphysics/src/collision.rs	Wed Jul 24 23:37:58 2019 +0300
+++ b/rust/hwphysics/src/collision.rs	Thu Jul 25 00:05:30 2019 +0300
@@ -79,7 +79,7 @@
 }
 
 pub struct DetectedCollisions {
-    pub pairs: Vec<(GearId, GearId)>,
+    pub pairs: Vec<(GearId, Option<GearId>)>,
     pub positions: Vec<Point>,
 }
 
@@ -91,7 +91,12 @@
         }
     }
 
-    pub fn push(&mut self, contact_gear_id1: GearId, contact_gear_id2: GearId, position: &FPPoint) {
+    pub fn push(
+        &mut self,
+        contact_gear_id1: GearId,
+        contact_gear_id2: Option<GearId>,
+        position: &FPPoint,
+    ) {
         self.pairs.push((contact_gear_id1, contact_gear_id2));
         self.positions.push(fppoint_round(&position));
     }
@@ -119,7 +124,7 @@
                 .any(|(y, r)| (&land[y][r]).iter().any(|v| *v != 0))
             {
                 self.detected_collisions
-                    .push(gear_id, 0, &collision.bounds.center)
+                    .push(gear_id, None, &collision.bounds.center)
             }
         }
     }

--- a/rust/hwphysics/src/common.rs	Wed Jul 24 23:37:58 2019 +0300
+++ b/rust/hwphysics/src/common.rs	Thu Jul 25 00:05:30 2019 +0300
@@ -1,4 +1,4 @@
-pub type GearId = u16;
+pub type GearId = std::num::NonZeroU16;
 pub trait GearData {}
 
 pub trait GearDataProcessor<T: GearData> {

--- a/rust/hwphysics/src/grid.rs	Wed Jul 24 23:37:58 2019 +0300
+++ b/rust/hwphysics/src/grid.rs	Thu Jul 25 00:05:30 2019 +0300
@@ -114,16 +114,24 @@
 
     pub fn check_collisions(&self, collisions: &mut DetectedCollisions) {
         for bin in &self.bins {
-            for bounds in &bin.dynamic_entries {
-                for other in &bin.dynamic_entries {
+            for (index, bounds) in bin.dynamic_entries.iter().enumerate() {
+                for (other_index, other) in bin.dynamic_entries.iter().enumerate().skip(index + 1) {
                     if bounds.intersects(other) && bounds != other {
-                        collisions.push(0, 0, &bounds.center)
+                        collisions.push(
+                            bin.dynamic_refs[index],
+                            Some(bin.dynamic_refs[other_index]),
+                            &bounds.center,
+                        )
                     }
                 }
 
-                for other in &bin.static_entries {
+                for (other_index, other) in bin.static_entries.iter().enumerate() {
                     if bounds.intersects(other) {
-                        collisions.push(0, 0, &bounds.center)
+                        collisions.push(
+                            bin.dynamic_refs[index],
+                            Some(bin.static_refs[other_index]),
+                            &bounds.center,
+                        )
                     }
                 }
             }

--- a/rust/lib-hedgewars-engine/src/world.rs	Wed Jul 24 23:37:58 2019 +0300
+++ b/rust/lib-hedgewars-engine/src/world.rs	Thu Jul 25 00:05:30 2019 +0300
@@ -40,7 +40,7 @@
             map_renderer: None,
             gear_renderer: None,
             camera: Camera::new(),
-            last_gear_id: GearId::default(),
+            last_gear_id: std::num::NonZeroU16::new(1).unwrap(),
         }
     }
 
@@ -130,7 +130,7 @@
 
     fn get_unused_gear_id(&mut self) -> GearId {
         let id = self.last_gear_id;
-        self.last_gear_id += 1;
+        self.last_gear_id = std::num::NonZeroU16::new(self.last_gear_id.get() + 1).unwrap();
         id
     }