diff --git a/src/face_crawler.rs b/src/face_crawler.rs
index 9e80789..d7a7e80 100644
--- a/src/face_crawler.rs
+++ b/src/face_crawler.rs
@@ -1,5 +1,5 @@
 use crate::physics::Body;
-use crate::integer::Time;
+use crate::integer::{Time,Planar64Vec3};
 
 struct VertexId(usize);
 struct EdgeId(usize);
@@ -24,24 +24,31 @@ enum Transition{
 }
 
 impl State{
-	fn next_transition(&self,mesh:&VirtualMesh,time_limit:Time)->Transition{
+	fn next_transition(&self,mesh:&VirtualMesh,body:&Body,time_limit:Time)->Transition{
 		//conflicting derivative means it crosses in the wrong direction.
-		match self.fev{
+		//if the transition time is equal to an already tested transition, do not replace the current best.
+		match &self.fev{
 			FEV::Face(face_id)=>{
-				//test own face collision time
+				//test own face collision time, ignoring edges with zero or conflicting derivative
 				//test each edge collision time, ignoring edges with zero or conflicting derivative
-				//if face: return (Face,Time)
-				//if edge: goto edge
+				//if face: Transition::Hit(Face,Time)
+				//if edge: Transition::NextState(State{time,fev:FEV::Edge(edge_id)})
+				//if none:
+				Transition::Miss
 			},
 			FEV::Edge(edge_id)=>{
 				//test each face collision time, ignoring faces with zero or conflicting derivative
 				//test each vertex collision time, ignoring vertices with zero or conflicting derivative
-				//if face: goto face
-				//if vertex: goto vertex
+				//if face: Transition::NextState(State{time,fev:FEV::Face(face_id)})
+				//if vert: Transition::NextState(State{time,fev:FEV::Vertex(vertex_id)})
+				//if none:
+				Transition::Miss
 			},
 			FEV::Vertex(vertex_id)=>{
 				//test each edge collision time, ignoring edges with zero or conflicting derivative
-				//goto edge
+				//if some: Transition::NextState(State{time,fev:FEV::Edge(edge_id)})
+				//if none:
+				Transition::Miss
 			},
 		}
 	}
@@ -52,24 +59,30 @@ impl State{
 //(edge,edge)
 //(vertex,face)
 
-struct VirtualMesh{
-	//???
+struct VirtualMesh<'a>{
+	mesh0:&'a PhysicsMesh,
+	mesh1:&'a PhysicsMesh,
 }
 
-impl VirtualMesh{
-	pub fn minkowski_sum(mesh0:&PhysicsMesh,mesh1:&PhysicsMesh)->Self{
-		//?????
+impl VirtualMesh<'_>{
+	pub fn minkowski_sum<'a>(mesh0:&PhysicsMesh,mesh1:&PhysicsMesh)->VirtualMesh<'a>{
+		Self{
+			mesh0,
+			mesh1,
+		}
 	}
-	pub fn predict_collision(&self,body:&Body,time:Time,time_limit:Time)->Option<(FaceId,Time)>{
-		//mesh.closest_point returns if the point is on a face, edge or vertex
-		let (point,fev)=self.closest_point(body.extrapolated_position(time));
+	fn closest_fev(&self,point:Planar64Vec3)->FEV{
+		//put some genius code right here
+		todo!()
+	}
+	pub fn predict_collision(&self,relative_body:&Body,time_limit:Time)->Option<(FaceId,Time)>{
 		let mut state=State{
-			time,
-			fev,
+			time:relative_body.time,
+			fev:self.closest_fev(relative_body.position),
 		};
 		//it would be possible to write down the point of closest approach...
 		loop{
-			match state.next_transition(self,time_limit){
+			match state.next_transition(self,relative_body,time_limit){
 				Transition::Miss=>return None,
 				Transition::NextState(next_state)=>state=next_state,
 				Transition::Hit(hit_face,hit_time)=>return Some((hit_face,hit_time)),