diff --git a/src/primitives.rs b/src/primitives.rs
index 2951071..772c694 100644
--- a/src/primitives.rs
+++ b/src/primitives.rs
@@ -215,7 +215,7 @@ pub fn generate_partial_unit_cube(face_descriptions:CubeFaceDescription)->Mesh{
 	let mut generated_vertices=Vec::new();
 	let mut polygon_groups=Vec::new();
 	let mut graphics_groups=Vec::new();
-	let mut physics_groups=vec![IndexedPhysicsGroup::default()];
+	let mut physics_group=IndexedPhysicsGroup::default();
 	let mut transforms=Vec::new();
 	//note that on a cube every vertex is guaranteed to be unique, so there's no need to hash them against existing vertices.
 	for (face_id,face_description) in face_descriptions.pairs(){
@@ -271,7 +271,7 @@ pub fn generate_partial_unit_cube(face_descriptions:CubeFaceDescription)->Mesh{
 			render:face_description.render,
 			groups:vec![group_id],
 		});
-		physics_groups[0].groups.push(group_id);
+		physics_group.groups.push(group_id);
 	}
 	Mesh{
 		unique_pos:generated_pos,
@@ -281,7 +281,7 @@ pub fn generate_partial_unit_cube(face_descriptions:CubeFaceDescription)->Mesh{
 		unique_vertices:generated_vertices,
 		polygon_groups,
 		graphics_groups,
-		physics_groups,
+		physics_groups:vec![physics_group],
 	}
 }
 //don't think too hard about the copy paste because this is all going into the map tool eventually...
@@ -328,7 +328,7 @@ pub fn generate_partial_unit_wedge(face_descriptions:WedgeFaceDescription)->Mesh
 	let mut generated_vertices=Vec::new();
 	let mut polygon_groups=Vec::new();
 	let mut graphics_groups=Vec::new();
-	let mut physics_groups=vec![IndexedPhysicsGroup::default()];
+	let mut physics_group=IndexedPhysicsGroup::default();
 	let mut transforms=Vec::new();
 	//note that on a cube every vertex is guaranteed to be unique, so there's no need to hash them against existing vertices.
 	for (face_id,face_description) in face_descriptions.pairs(){
@@ -384,7 +384,7 @@ pub fn generate_partial_unit_wedge(face_descriptions:WedgeFaceDescription)->Mesh
 			render:face_description.render,
 			groups:vec![group_id],
 		});
-		physics_groups[0].groups.push(group_id);
+		physics_group.groups.push(group_id);
 	}
 	Mesh{
 		unique_pos:generated_pos,
@@ -394,7 +394,7 @@ pub fn generate_partial_unit_wedge(face_descriptions:WedgeFaceDescription)->Mesh
 		unique_vertices:generated_vertices,
 		polygon_groups,
 		graphics_groups,
-		physics_groups,
+		physics_groups:vec![physics_group],
 	}
 }
 
@@ -439,7 +439,7 @@ pub fn generate_partial_unit_cornerwedge(face_descriptions:CornerWedgeFaceDescri
 	let mut generated_vertices=Vec::new();
 	let mut polygon_groups=Vec::new();
 	let mut graphics_groups=Vec::new();
-	let mut physics_groups=vec![IndexedPhysicsGroup::default()];
+	let mut physics_group=IndexedPhysicsGroup::default();
 	let mut transforms=Vec::new();
 	//note that on a cube every vertex is guaranteed to be unique, so there's no need to hash them against existing vertices.
 	for (face_id,face_description) in face_descriptions.pairs(){
@@ -495,7 +495,7 @@ pub fn generate_partial_unit_cornerwedge(face_descriptions:CornerWedgeFaceDescri
 			render:face_description.render,
 			groups:vec![group_id],
 		});
-		physics_groups[0].groups.push(group_id);
+		physics_group.groups.push(group_id);
 	}
 	Mesh{
 		unique_pos:generated_pos,
@@ -505,6 +505,6 @@ pub fn generate_partial_unit_cornerwedge(face_descriptions:CornerWedgeFaceDescri
 		unique_vertices:generated_vertices,
 		polygon_groups,
 		graphics_groups,
-		physics_groups,
+		physics_groups:vec![physics_group],
 	}
 }