From b05d4349432dada25f9f51a58046de2d7544ec4c Mon Sep 17 00:00:00 2001
From: Rhys Lloyd <krakow20@gmail.com>
Date: Tue, 27 Jan 2026 08:30:10 -0800
Subject: [PATCH 1/3] body

---
 engine/physics/src/body.rs | 85 +++++++++++++++++++++++---------------
 1 file changed, 51 insertions(+), 34 deletions(-)

diff --git a/engine/physics/src/body.rs b/engine/physics/src/body.rs
index e1b69f0b..eb4534d1 100644
--- a/engine/physics/src/body.rs
+++ b/engine/physics/src/body.rs
@@ -2,12 +2,18 @@ use strafesnet_common::aabb;
 use strafesnet_common::integer::{self,vec3,Time,Planar64,Planar64Vec3};
 #[derive(Clone,Copy,Debug,Hash)]
 pub struct Body<T>{
-	pub position:Planar64Vec3,//I64 where 2^32 = 1 u
-	pub velocity:Planar64Vec3,//I64 where 2^32 = 1 u/s
-	pub acceleration:Planar64Vec3,//I64 where 2^32 = 1 u/s/s
-	pub time:Time<T>,//nanoseconds x xxxxD!
+	pub position:Planar64Vec3,
+	pub velocity:Planar64Vec3,
+	pub time:Time<T>,
 }
-impl<T> std::ops::Neg for Body<T>{
+#[derive(Clone,Copy,Debug,Hash)]
+pub struct Trajectory<T>{
+	pub position:Planar64Vec3,
+	pub velocity:Planar64Vec3,
+	pub acceleration:Planar64Vec3,
+	pub time:Time<T>,
+}
+impl<T> std::ops::Neg for Trajectory<T>{
 	type Output=Self;
 	fn neg(self)->Self::Output{
 		Self{
@@ -18,10 +24,10 @@ impl<T> std::ops::Neg for Body<T>{
 		}
 	}
 }
-impl<T:Copy> std::ops::Neg for &Body<T>{
-	type Output=Body<T>;
+impl<T:Copy> std::ops::Neg for &Trajectory<T>{
+	type Output=Trajectory<T>;
 	fn neg(self)->Self::Output{
-		Body{
+		Trajectory{
 			position:self.position,
 			velocity:-self.velocity,
 			acceleration:self.acceleration,
@@ -32,6 +38,19 @@ impl<T:Copy> std::ops::Neg for &Body<T>{
 
 impl<T> Body<T>
 	where Time<T>:Copy,
+{
+	pub const ZERO:Self=Self::new(vec3::zero(),vec3::zero(),Time::ZERO);
+	pub const fn new(position:Planar64Vec3,velocity:Planar64Vec3,time:Time<T>)->Self{
+		Self{
+			position,
+			velocity,
+			time,
+		}
+	}
+}
+
+impl<T> Trajectory<T>
+	where Time<T>:Copy,
 {
 	pub const ZERO:Self=Self::new(vec3::zero(),vec3::zero(),vec3::zero(),Time::ZERO);
 	pub const fn new(position:Planar64Vec3,velocity:Planar64Vec3,acceleration:Planar64Vec3,time:Time<T>)->Self{
@@ -42,13 +61,27 @@ impl<T> Body<T>
 			time,
 		}
 	}
-	pub const fn relative_to<'a>(&'a self,body0:&'a Body<T>)->VirtualBody<'a,T>{
+	pub const fn body_with_acceleration(body:Body<T>,acceleration:Planar64Vec3)->Trajectory<T>{
+		let Body{
+			position,
+			velocity,
+			time,
+		}=body;
+		Self{
+			position,
+			velocity,
+			acceleration,
+			time,
+		}
+	}
+	pub fn relative_to(&self,trj0:&Trajectory<T>,time:Time<T>)->Trajectory<T>{
 		//(p0,v0,a0,t0)
 		//(p1,v1,a1,t1)
-		VirtualBody{
-			body0,
-			body1:self,
-		}
+		Trajectory::new(
+			self.extrapolated_position(time)-trj0.extrapolated_position(time),
+			self.extrapolated_velocity(time)-trj0.extrapolated_velocity(time),
+			self.acceleration-trj0.acceleration,
+			time)
 	}
 	pub fn extrapolated_position(&self,time:Time<T>)->Planar64Vec3{
 		let dt=time-self.time;
@@ -144,28 +177,12 @@ impl<T> Body<T>
 
 }
 impl<T> std::fmt::Display for Body<T>{
+	fn fmt(&self,f:&mut std::fmt::Formatter<'_>)->std::fmt::Result{
+		write!(f,"p({}) v({}) t({})",self.position,self.velocity,self.time)
+	}
+}
+impl<T> std::fmt::Display for Trajectory<T>{
 	fn fmt(&self,f:&mut std::fmt::Formatter<'_>)->std::fmt::Result{
 		write!(f,"p({}) v({}) a({}) t({})",self.position,self.velocity,self.acceleration,self.time)
 	}
 }
-
-pub struct VirtualBody<'a,T>{
-	body0:&'a Body<T>,
-	body1:&'a Body<T>,
-}
-impl<T> VirtualBody<'_,T>
-	where Time<T>:Copy,
-{
-	pub fn extrapolated_position(&self,time:Time<T>)->Planar64Vec3{
-		self.body1.extrapolated_position(time)-self.body0.extrapolated_position(time)
-	}
-	pub fn extrapolated_velocity(&self,time:Time<T>)->Planar64Vec3{
-		self.body1.extrapolated_velocity(time)-self.body0.extrapolated_velocity(time)
-	}
-	pub fn acceleration(&self)->Planar64Vec3{
-		self.body1.acceleration-self.body0.acceleration
-	}
-	pub fn body(&self,time:Time<T>)->Body<T>{
-		Body::new(self.extrapolated_position(time),self.extrapolated_velocity(time),self.acceleration(),time)
-	}
-}
-- 
2.49.1


From b918772a00c9f9bafce185705600363fb99a2486 Mon Sep 17 00:00:00 2001
From: Rhys Lloyd <krakow20@gmail.com>
Date: Tue, 27 Jan 2026 08:55:27 -0800
Subject: [PATCH 2/3] DELETE Body.acceleration

---
 engine/graphics/src/graphics.rs        |   2 +-
 engine/physics/src/body.rs             |  46 +++---
 engine/physics/src/face_crawler.rs     |  34 ++---
 engine/physics/src/model.rs            |  34 ++---
 engine/physics/src/physics.rs          | 194 +++++++++++--------------
 engine/session/src/session.rs          |  10 +-
 integration-testing/src/main.rs        |   8 +-
 integration-testing/src/test_scenes.rs |   4 -
 integration-testing/src/tests.rs       |   2 -
 9 files changed, 151 insertions(+), 183 deletions(-)

diff --git a/engine/graphics/src/graphics.rs b/engine/graphics/src/graphics.rs
index dc1f9e16..90452239 100644
--- a/engine/graphics/src/graphics.rs
+++ b/engine/graphics/src/graphics.rs
@@ -909,7 +909,7 @@ impl GraphicsState{
 
 		// update rotation
 		let camera_uniforms=self.camera.to_uniform_data(
-			frame_state.body.extrapolated_position(frame_state.time).map(Into::<f32>::into).to_array().into(),
+			frame_state.trajectory.extrapolated_position(frame_state.time).map(Into::<f32>::into).to_array().into(),
 			frame_state.camera.simulate_move_angles(glam::IVec2::ZERO)
 		);
 		self.staging_belt
diff --git a/engine/physics/src/body.rs b/engine/physics/src/body.rs
index eb4534d1..4f676805 100644
--- a/engine/physics/src/body.rs
+++ b/engine/physics/src/body.rs
@@ -47,6 +47,19 @@ impl<T> Body<T>
 			time,
 		}
 	}
+	pub const fn with_acceleration(self,acceleration:Planar64Vec3)->Trajectory<T>{
+		let Body{
+			position,
+			velocity,
+			time,
+		}=self;
+		Trajectory{
+			position,
+			velocity,
+			acceleration,
+			time,
+		}
+	}
 }
 
 impl<T> Trajectory<T>
@@ -61,19 +74,6 @@ impl<T> Trajectory<T>
 			time,
 		}
 	}
-	pub const fn body_with_acceleration(body:Body<T>,acceleration:Planar64Vec3)->Trajectory<T>{
-		let Body{
-			position,
-			velocity,
-			time,
-		}=body;
-		Self{
-			position,
-			velocity,
-			acceleration,
-			time,
-		}
-	}
 	pub fn relative_to(&self,trj0:&Trajectory<T>,time:Time<T>)->Trajectory<T>{
 		//(p0,v0,a0,t0)
 		//(p1,v1,a1,t1)
@@ -93,10 +93,12 @@ impl<T> Trajectory<T>
 		let dt=time-self.time;
 		self.velocity+(self.acceleration*dt).map(|elem|elem.divide().clamp_1())
 	}
-	pub fn advance_time(&mut self,time:Time<T>){
-		self.position=self.extrapolated_position(time);
-		self.velocity=self.extrapolated_velocity(time);
-		self.time=time;
+	pub fn extrapolated_body(&self,time:Time<T>)->Body<T>{
+		Body::new(
+			self.extrapolated_position(time),
+			self.extrapolated_velocity(time),
+			time,
+		)
 	}
 	pub fn extrapolated_position_ratio_dt<Num,Den,N1,D1,N2,N3,D2,N4,T1>(&self,dt:integer::Ratio<Num,Den>)->Planar64Vec3
 		where
@@ -134,10 +136,12 @@ impl<T> Trajectory<T>
 		// a*dt + v
 		self.acceleration.map(|elem|(dt*elem).divide().clamp())+self.velocity
 	}
-	pub fn advance_time_ratio_dt(&mut self,dt:crate::model::GigaTime){
-		self.position=self.extrapolated_position_ratio_dt(dt);
-		self.velocity=self.extrapolated_velocity_ratio_dt(dt);
-		self.time+=dt.into();
+	pub fn extrapolated_body_ratio_dt(&self,dt:crate::model::GigaTime)->Body<T>{
+		Body::new(
+			self.extrapolated_position_ratio_dt(dt),
+			self.extrapolated_velocity_ratio_dt(dt),
+			self.time+dt.into(),
+		)
 	}
 	pub fn infinity_dir(&self)->Option<Planar64Vec3>{
 		if self.velocity==vec3::zero(){
diff --git a/engine/physics/src/face_crawler.rs b/engine/physics/src/face_crawler.rs
index 44cfb914..3cc3e1cf 100644
--- a/engine/physics/src/face_crawler.rs
+++ b/engine/physics/src/face_crawler.rs
@@ -1,6 +1,6 @@
 use crate::model::{into_giga_time,GigaTime,FEV,MeshQuery,DirectedEdge};
 use strafesnet_common::integer::{Fixed,Ratio,vec3::Vector3};
-use crate::physics::{Time,Body};
+use crate::physics::{Time,Trajectory};
 
 use core::ops::Bound;
 
@@ -74,7 +74,7 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 		<F as core::ops::Mul<Fixed<1,32>>>::Output:core::iter::Sum,
 		M::Offset:core::ops::Sub<<F as std::ops::Mul<Fixed<1,32>>>::Output>,
 {
-	fn next_transition(&self,mesh:&M,body:&Body,lower_bound:Bound<GigaTime>,mut upper_bound:Bound<GigaTime>)->Transition<M>{
+	fn next_transition(&self,mesh:&M,trajectory:&Trajectory,lower_bound:Bound<GigaTime>,mut upper_bound:Bound<GigaTime>)->Transition<M>{
 		//conflicting derivative means it crosses in the wrong direction.
 		//if the transition time is equal to an already tested transition, do not replace the current best.
 		let mut best_transition=Transition::Miss;
@@ -86,8 +86,8 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 				let (n,d)=mesh.face_nd(face_id);
 				//TODO: use higher precision d value?
 				//use the mesh transform translation instead of baking it into the d value.
-				for dt in Fixed::<4,128>::zeroes2((n.dot(body.position)-d)*2,n.dot(body.velocity)*2,n.dot(body.acceleration)){
-					if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+				for dt in Fixed::<4,128>::zeroes2((n.dot(trajectory.position)-d)*2,n.dot(trajectory.velocity)*2,n.dot(trajectory.acceleration)){
+					if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 						upper_bound=Bound::Included(dt);
 						best_transition=Transition::Hit(face_id,dt);
 						break;
@@ -101,8 +101,8 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 					//WARNING: d is moved out of the *2 block because of adding two vertices!
 					//WARNING: precision is swept under the rug!
 					//wrap for speed
-					for dt in Fixed::<4,128>::zeroes2(n.dot(body.position*2-(mesh.vert(v0)+mesh.vert(v1))).wrap_4(),n.dot(body.velocity).wrap_4()*2,n.dot(body.acceleration).wrap_4()){
-						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+					for dt in Fixed::<4,128>::zeroes2(n.dot(trajectory.position*2-(mesh.vert(v0)+mesh.vert(v1))).wrap_4(),n.dot(trajectory.velocity).wrap_4()*2,n.dot(trajectory.acceleration).wrap_4()){
+						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 							upper_bound=Bound::Included(dt);
 							best_transition=Transition::Next(FEV::Edge(directed_edge_id.as_undirected()),dt);
 							break;
@@ -117,15 +117,15 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 				let &[ev0,ev1]=edge_verts.as_ref();
 				let (v0,v1)=(mesh.vert(ev0),mesh.vert(ev1));
 				let edge_n=v1-v0;
-				let delta_pos=body.position*2-(v0+v1);
+				let delta_pos=trajectory.position*2-(v0+v1);
 				for (i,&edge_face_id) in mesh.edge_faces(edge_id).as_ref().iter().enumerate(){
 					let face_n=mesh.face_nd(edge_face_id).0;
 					//edge_n gets parity from the order of edge_faces
 					let n=face_n.cross(edge_n)*((i as i64)*2-1);
 					//WARNING yada yada d *2
 					//wrap for speed
-					for dt in Fixed::<4,128>::zeroes2(n.dot(delta_pos).wrap_4(),n.dot(body.velocity).wrap_4()*2,n.dot(body.acceleration).wrap_4()){
-						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+					for dt in Fixed::<4,128>::zeroes2(n.dot(delta_pos).wrap_4(),n.dot(trajectory.velocity).wrap_4()*2,n.dot(trajectory.acceleration).wrap_4()){
+						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 							upper_bound=Bound::Included(dt);
 							best_transition=Transition::Next(FEV::Face(edge_face_id),dt);
 							break;
@@ -136,8 +136,8 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 				for (i,&vert_id) in edge_verts.as_ref().iter().enumerate(){
 					//vertex normal gets parity from vert index
 					let n=edge_n*(1-2*(i as i64));
-					for dt in Fixed::<2,64>::zeroes2((n.dot(body.position-mesh.vert(vert_id)))*2,n.dot(body.velocity)*2,n.dot(body.acceleration)){
-						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+					for dt in Fixed::<2,64>::zeroes2((n.dot(trajectory.position-mesh.vert(vert_id)))*2,n.dot(trajectory.velocity)*2,n.dot(trajectory.acceleration)){
+						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 							let dt=Ratio::new(dt.num.widen_4(),dt.den.widen_4());
 							upper_bound=Bound::Included(dt);
 							best_transition=Transition::Next(FEV::Vert(vert_id),dt);
@@ -152,8 +152,8 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 				for &directed_edge_id in mesh.vert_edges(vert_id).as_ref(){
 					//edge is directed away from vertex, but we want the dot product to turn out negative
 					let n=-mesh.directed_edge_n(directed_edge_id);
-					for dt in Fixed::<2,64>::zeroes2((n.dot(body.position-mesh.vert(vert_id)))*2,n.dot(body.velocity)*2,n.dot(body.acceleration)){
-						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+					for dt in Fixed::<2,64>::zeroes2((n.dot(trajectory.position-mesh.vert(vert_id)))*2,n.dot(trajectory.velocity)*2,n.dot(trajectory.acceleration)){
+						if low(&lower_bound,&dt)&&upp(&dt,&upper_bound)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 							let dt=Ratio::new(dt.num.widen_4(),dt.den.widen_4());
 							upper_bound=Bound::Included(dt);
 							best_transition=Transition::Next(FEV::Edge(directed_edge_id.as_undirected()),dt);
@@ -166,11 +166,11 @@ impl<F:Copy,M:MeshQuery<Normal=Vector3<F>,Offset=Fixed<4,128>>> FEV<M>
 		}
 		best_transition
 	}
-	pub fn crawl(mut self,mesh:&M,relative_body:&Body,lower_bound:Bound<&Time>,upper_bound:Bound<&Time>)->CrawlResult<M>{
-		let mut lower_bound=lower_bound.map(|&t|into_giga_time(t,relative_body.time));
-		let upper_bound=upper_bound.map(|&t|into_giga_time(t,relative_body.time));
+	pub fn crawl(mut self,mesh:&M,trajectory:&Trajectory,lower_bound:Bound<&Time>,upper_bound:Bound<&Time>)->CrawlResult<M>{
+		let mut lower_bound=lower_bound.map(|&t|into_giga_time(t,trajectory.time));
+		let upper_bound=upper_bound.map(|&t|into_giga_time(t,trajectory.time));
 		for _ in 0..20{
-			match self.next_transition(mesh,relative_body,lower_bound,upper_bound){
+			match self.next_transition(mesh,trajectory,lower_bound,upper_bound){
 				Transition::Miss=>return CrawlResult::Miss(self),
 				Transition::Next(next_fev,next_time)=>(self,lower_bound)=(next_fev,Bound::Included(next_time)),
 				Transition::Hit(face,time)=>return CrawlResult::Hit(face,time),
diff --git a/engine/physics/src/model.rs b/engine/physics/src/model.rs
index 57dc0618..4809fbcf 100644
--- a/engine/physics/src/model.rs
+++ b/engine/physics/src/model.rs
@@ -5,7 +5,7 @@ use strafesnet_common::model::{self,MeshId,PolygonIter};
 use strafesnet_common::integer::{self,vec3,Fixed,Planar64,Planar64Vec3,Ratio};
 use strafesnet_common::physics::Time;
 
-type Body=crate::body::Body<strafesnet_common::physics::TimeInner>;
+type Trajectory=crate::body::Trajectory<strafesnet_common::physics::TimeInner>;
 
 struct AsRefHelper<T>(T);
 impl<T> AsRef<T> for AsRefHelper<T>{
@@ -670,40 +670,40 @@ impl MinkowskiMesh<'_>{
 			mesh1,
 		}
 	}
-	pub fn predict_collision_in(&self,relative_body:&Body,range:impl RangeBounds<Time>)->Option<(MinkowskiFace,GigaTime)>{
+	pub fn predict_collision_in(&self,trajectory:&Trajectory,range:impl RangeBounds<Time>)->Option<(MinkowskiFace,GigaTime)>{
 		let start_position=match range.start_bound(){
-			Bound::Included(time)=>relative_body.extrapolated_position(*time),
-			Bound::Excluded(time)=>relative_body.extrapolated_position(*time),
-			Bound::Unbounded=>relative_body.position,
+			Bound::Included(time)=>trajectory.extrapolated_position(*time),
+			Bound::Excluded(time)=>trajectory.extrapolated_position(*time),
+			Bound::Unbounded=>trajectory.position,
 		};
 		let fev=crate::minimum_difference::closest_fev_not_inside(self,start_position)?;
 		//continue forwards along the body parabola
-		fev.crawl(self,relative_body,range.start_bound(),range.end_bound()).hit()
+		fev.crawl(self,trajectory,range.start_bound(),range.end_bound()).hit()
 	}
-	pub fn predict_collision_out(&self,relative_body:&Body,range:impl RangeBounds<Time>)->Option<(MinkowskiFace,GigaTime)>{
+	pub fn predict_collision_out(&self,trajectory:&Trajectory,range:impl RangeBounds<Time>)->Option<(MinkowskiFace,GigaTime)>{
 		let (lower_bound,upper_bound)=(range.start_bound(),range.end_bound());
 		// TODO: handle unbounded collision using infinity fev
 		let start_position=match upper_bound{
-			Bound::Included(time)=>relative_body.extrapolated_position(*time),
-			Bound::Excluded(time)=>relative_body.extrapolated_position(*time),
-			Bound::Unbounded=>relative_body.position,
+			Bound::Included(time)=>trajectory.extrapolated_position(*time),
+			Bound::Excluded(time)=>trajectory.extrapolated_position(*time),
+			Bound::Unbounded=>trajectory.position,
 		};
 		let fev=crate::minimum_difference::closest_fev_not_inside(self,start_position)?;
 		// swap and negate bounds to do a time inversion
 		let (lower_bound,upper_bound)=(upper_bound.map(|&t|-t),lower_bound.map(|&t|-t));
-		let infinity_body=-relative_body;
+		let time_reversed_trajectory=-trajectory;
 		//continue backwards along the body parabola
-		fev.crawl(self,&infinity_body,lower_bound.as_ref(),upper_bound.as_ref()).hit()
+		fev.crawl(self,&time_reversed_trajectory,lower_bound.as_ref(),upper_bound.as_ref()).hit()
 			//no need to test -time<time_limit because of the first step
 			.map(|(face,time)|(face,-time))
 	}
-	pub fn predict_collision_face_out(&self,relative_body:&Body,range:impl RangeBounds<Time>,contact_face_id:MinkowskiFace)->Option<(MinkowskiDirectedEdge,GigaTime)>{
+	pub fn predict_collision_face_out(&self,trajectory:&Trajectory,range:impl RangeBounds<Time>,contact_face_id:MinkowskiFace)->Option<(MinkowskiDirectedEdge,GigaTime)>{
 		// TODO: make better
 		use crate::face_crawler::{low,upp};
 		//no algorithm needed, there is only one state and two cases (Edge,None)
 		//determine when it passes an edge ("sliding off" case)
-		let start_time=range.start_bound().map(|&t|(t-relative_body.time).to_ratio());
-		let mut best_time=range.end_bound().map(|&t|into_giga_time(t,relative_body.time));
+		let start_time=range.start_bound().map(|&t|(t-trajectory.time).to_ratio());
+		let mut best_time=range.end_bound().map(|&t|into_giga_time(t,trajectory.time));
 		let mut best_edge=None;
 		let face_n=self.face_nd(contact_face_id).0;
 		for &directed_edge_id in self.face_edges(contact_face_id).as_ref(){
@@ -715,8 +715,8 @@ impl MinkowskiMesh<'_>{
 			//WARNING! d outside of *2
 			//WARNING: truncated precision
 			//wrap for speed
-			for dt in Fixed::<4,128>::zeroes2(((n.dot(relative_body.position))*2-d).wrap_4(),n.dot(relative_body.velocity).wrap_4()*2,n.dot(relative_body.acceleration).wrap_4()){
-				if low(&start_time,&dt)&&upp(&dt,&best_time)&&n.dot(relative_body.extrapolated_velocity_ratio_dt(dt)).is_negative(){
+			for dt in Fixed::<4,128>::zeroes2(((n.dot(trajectory.position))*2-d).wrap_4(),n.dot(trajectory.velocity).wrap_4()*2,n.dot(trajectory.acceleration).wrap_4()){
+				if low(&start_time,&dt)&&upp(&dt,&best_time)&&n.dot(trajectory.extrapolated_velocity_ratio_dt(dt)).is_negative(){
 					best_time=Bound::Included(dt);
 					best_edge=Some((directed_edge_id,dt));
 					break;
diff --git a/engine/physics/src/physics.rs b/engine/physics/src/physics.rs
index 905569fb..8275abf0 100644
--- a/engine/physics/src/physics.rs
+++ b/engine/physics/src/physics.rs
@@ -15,6 +15,7 @@ pub use strafesnet_common::physics::{Time,TimeInner};
 use gameplay::ModeState;
 
 pub type Body=crate::body::Body<TimeInner>;
+pub type Trajectory=crate::body::Trajectory<TimeInner>;
 type MouseState=strafesnet_common::mouse::MouseState<TimeInner>;
 
 //external influence
@@ -498,19 +499,6 @@ enum MoveState{
 	Fly,
 }
 impl MoveState{
-	//call this after state.move_state is changed
-	fn apply_enum(&self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
-		match self{
-			MoveState::Fly=>body.acceleration=vec3::zero(),
-			MoveState::Air=>{
-				//calculate base acceleration
-				let a=touching.base_acceleration(models,style,camera,input_state);
-				//set_acceleration clips according to contacts
-				set_acceleration(body,touching,models,hitbox_mesh,a);
-			},
-			_=>(),
-		}
-	}
 	//function to coerce &mut self into &self
 	fn apply_to_body(&self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
 		match self{
@@ -522,13 +510,9 @@ impl MoveState{
 				//set_velocity clips velocity according to current touching state
 				set_velocity(body,touching,models,hitbox_mesh,v);
 			},
-			MoveState::Walk(walk_state)
-			|MoveState::Ladder(walk_state)
-			=>{
-				//accelerate towards walk target or do nothing
-				let a=walk_state.target.acceleration();
-				set_acceleration(body,touching,models,hitbox_mesh,a);
-			},
+			MoveState::Walk(_walk_state)
+			|MoveState::Ladder(_walk_state)
+			=>(),
 		}
 	}
 	/// changes the move state
@@ -591,12 +575,10 @@ impl MoveState{
 	}
 	//lmao idk this is convenient
 	fn apply_enum_and_input_and_body(&mut self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
-		self.apply_enum(body,touching,models,hitbox_mesh,style,camera,input_state);
 		self.apply_input(body,touching,models,hitbox_mesh,style,camera,input_state);
 		self.apply_to_body(body,touching,models,hitbox_mesh,style,camera,input_state);
 	}
 	fn apply_enum_and_body(&mut self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
-		self.apply_enum(body,touching,models,hitbox_mesh,style,camera,input_state);
 		self.apply_to_body(body,touching,models,hitbox_mesh,style,camera,input_state);
 	}
 	fn apply_input_and_body(&mut self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
@@ -829,16 +811,15 @@ impl TouchingState{
 		}).collect();
 		crate::push_solve::push_solve(&contacts,acceleration)
 	}
-	fn predict_collision_end(&self,collector:&mut instruction::InstructionCollector<InternalInstruction,Time>,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,body:&Body,start_time:Time){
+	fn predict_collision_end(&self,collector:&mut instruction::InstructionCollector<InternalInstruction,Time>,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,trajectory:&Trajectory,start_time:Time){
 		// let relative_body=body.relative_to(&Body::ZERO);
-		let relative_body=body;
 		for (convex_mesh_id,face_id) in &self.contacts{
 			//detect face slide off
 			let model_mesh=models.contact_mesh(convex_mesh_id);
 			let minkowski=model_physics::MinkowskiMesh::minkowski_sum(model_mesh,hitbox_mesh.transformed_mesh());
-			collector.collect(minkowski.predict_collision_face_out(&relative_body,start_time..collector.time(),*face_id).map(|(_face,time)|{
+			collector.collect(minkowski.predict_collision_face_out(&trajectory,start_time..collector.time(),*face_id).map(|(_face,time)|{
 				TimedInstruction{
-					time:relative_body.time+time.into(),
+					time:trajectory.time+time.into(),
 					instruction:InternalInstruction::CollisionEnd(
 						Collision::Contact(ContactCollision{face_id:*face_id,convex_mesh_id:*convex_mesh_id}),
 						time
@@ -850,9 +831,9 @@ impl TouchingState{
 			//detect model collision in reverse
 			let model_mesh=models.intersect_mesh(convex_mesh_id);
 			let minkowski=model_physics::MinkowskiMesh::minkowski_sum(model_mesh,hitbox_mesh.transformed_mesh());
-			collector.collect(minkowski.predict_collision_out(&relative_body,start_time..collector.time()).map(|(_face,time)|{
+			collector.collect(minkowski.predict_collision_out(&trajectory,start_time..collector.time()).map(|(_face,time)|{
 				TimedInstruction{
-					time:relative_body.time+time.into(),
+					time:trajectory.time+time.into(),
 					instruction:InternalInstruction::CollisionEnd(
 						Collision::Intersect(IntersectCollision{convex_mesh_id:*convex_mesh_id}),
 						time
@@ -887,7 +868,7 @@ pub struct PhysicsState{
 impl Default for PhysicsState{
 	fn default()->Self{
  		Self{
-			body:Body::new(vec3::int(0,50,0),vec3::int(0,0,0),vec3::int(0,-100,0),Time::ZERO),
+			body:Body::new(vec3::int(0,50,0),vec3::int(0,0,0),Time::ZERO),
 			time:Time::ZERO,
 			style:StyleModifiers::default(),
 			touching:TouchingState::default(),
@@ -911,11 +892,14 @@ impl PhysicsState{
 	pub const fn body(&self)->&Body{
 		&self.body
 	}
-	pub fn camera_body(&self)->Body{
-		Body{
-			position:self.body.position+self.style.camera_offset,
-			..self.body
-		}
+	pub fn camera_trajectory(&self,data:&PhysicsData)->Trajectory{
+		let acceleration=self.acceleration(data);
+		Trajectory::new(
+			self.body.position+self.style.camera_offset,
+			self.body.velocity,
+			acceleration,
+			self.body.time,
+		)
 	}
 	pub const fn camera(&self)->PhysicsCamera{
 		self.camera
@@ -947,6 +931,10 @@ impl PhysicsState{
 	fn apply_input_and_body(&mut self,data:&PhysicsData){
 		self.move_state.apply_input_and_body(&mut self.body,&self.touching,&data.models,&data.hitbox_mesh,&self.style,&self.camera,&self.input_state);
 	}
+	fn acceleration(&self,data:&PhysicsData)->Planar64Vec3{
+		let base_acceleration=self.touching.base_acceleration(&data.models,&self.style,&self.camera,&self.input_state);
+		self.touching.constrain_acceleration(&data.models,&data.hitbox_mesh,base_acceleration)
+	}
 	//state mutated on collision:
 	//Accelerator
 	//stair step-up
@@ -1199,15 +1187,15 @@ impl<'a> PhysicsContext<'a>{
 
 		collector.collect(state.next_move_instruction());
 
+		let trajectory=state.body.with_acceleration(state.acceleration(data));
 		//check for collision ends
-		state.touching.predict_collision_end(&mut collector,&data.models,&data.hitbox_mesh,&state.body,state.time);
+		state.touching.predict_collision_end(&mut collector,&data.models,&data.hitbox_mesh,&trajectory,state.time);
 		//check for collision starts
 		let mut aabb=aabb::Aabb::default();
-		state.body.grow_aabb(&mut aabb,state.time,collector.time());
+		trajectory.grow_aabb(&mut aabb,state.time,collector.time());
 		aabb.inflate(data.hitbox_mesh.halfsize);
 		//relative to moving platforms
 		//let relative_body=state.body.relative_to(&Body::ZERO);
-		let relative_body=&state.body;
 		data.bvh.sample_aabb(&aabb,&mut |convex_mesh_id|{
 			if state.touching.contains(convex_mesh_id){
 				return;
@@ -1215,10 +1203,10 @@ impl<'a> PhysicsContext<'a>{
 			//no checks are needed because of the time limits.
 			let model_mesh=data.models.mesh(*convex_mesh_id);
 			let minkowski=model_physics::MinkowskiMesh::minkowski_sum(model_mesh,data.hitbox_mesh.transformed_mesh());
-			collector.collect(minkowski.predict_collision_in(relative_body,state.time..collector.time())
+			collector.collect(minkowski.predict_collision_in(&trajectory,state.time..collector.time())
 				.map(|(face,dt)|
 					TimedInstruction{
-						time:relative_body.time+dt.into(),
+						time:trajectory.time+dt.into(),
 						instruction:InternalInstruction::CollisionStart(
 							Collision::new(*convex_mesh_id,face),
 							dt
@@ -1336,24 +1324,6 @@ fn set_velocity_cull(body:&mut Body,touching:&mut TouchingState,models:&PhysicsM
 fn set_velocity(body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,v:Planar64Vec3){
 	body.velocity=touching.constrain_velocity(models,hitbox_mesh,v);
 }
-#[expect(dead_code)]
-fn set_acceleration_cull(body:&mut Body,touching:&mut TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,a:Planar64Vec3)->bool{
-	//This is not correct but is better than what I have
-	let mut culled=false;
-	touching.contacts.retain(|convex_mesh_id,face_id|{
-		let n=contact_normal(models,hitbox_mesh,convex_mesh_id,*face_id);
-		let r=n.dot(a).is_positive();
-		if r{
-			culled=true;
-		}
-		!r
-	});
-	set_acceleration(body,touching,models,hitbox_mesh,a);
-	culled
-}
-fn set_acceleration(body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,a:Planar64Vec3){
-	body.acceleration=touching.constrain_acceleration(models,hitbox_mesh,a);
-}
 
 fn teleport(
 	point:Planar64Vec3,
@@ -1372,7 +1342,6 @@ fn teleport(
 	time:Time,
 ){
 	set_position(point,move_state,body,touching,run,mode_state,mode,models,hitbox_mesh,bvh,style,camera,input_state,time);
-	set_acceleration(body,touching,models,hitbox_mesh,style.gravity);
 }
 enum TeleportToSpawnError{
 	NoModel,
@@ -1760,9 +1729,11 @@ fn atomic_internal_instruction(state:&mut PhysicsState,data:&PhysicsData,ins:Tim
 	match ins.instruction{
 		// collisions advance the body precisely
 		InternalInstruction::CollisionStart(_,dt)
-		|InternalInstruction::CollisionEnd(_,dt)=>state.body.advance_time_ratio_dt(dt),
+		|InternalInstruction::CollisionEnd(_,dt)=>{
+			state.body=state.body.with_acceleration(state.acceleration(data)).extrapolated_body_ratio_dt(dt);
+		},
 		// this advances imprecisely
-		InternalInstruction::ReachWalkTargetVelocity=>state.body.advance_time(state.time),
+		InternalInstruction::ReachWalkTargetVelocity=>state.body=state.body.with_acceleration(state.acceleration(data)).extrapolated_body(state.time),
 		// strafe tick decides for itself whether to advance the body.
 		InternalInstruction::StrafeTick=>(),
 	}
@@ -1812,7 +1783,7 @@ fn atomic_internal_instruction(state:&mut PhysicsState,data:&PhysicsData,ins:Tim
 					let control_dir=state.style.get_control_dir(masked_controls);
 					if control_dir!=vec3::zero(){
 						// manually advance time
-						state.body.advance_time(state.time);
+						state.body=state.body.with_acceleration(state.acceleration(data)).extrapolated_body(state.time);
 						let camera_mat=state.camera.simulate_move_rotation_y(state.input_state.lerp_delta(state.time).x);
 						if let Some(ticked_velocity)=strafe_settings.tick_velocity(state.body.velocity,(camera_mat*control_dir).with_length(Planar64::ONE).divide().wrap_1()){
 							//this is wrong but will work ig
@@ -1830,12 +1801,11 @@ fn atomic_internal_instruction(state:&mut PhysicsState,data:&PhysicsData,ins:Tim
 				|MoveState::Fly
 				=>println!("ReachWalkTargetVelocity fired for non-walking MoveState"),
 				MoveState::Walk(walk_state)|MoveState::Ladder(walk_state)=>{
-					//velocity is already handled by advance_time
+					//velocity is already handled by extrapolated_body
 					//we know that the acceleration is precisely zero because the walk target is known to be reachable
 					//which means that gravity can be fully cancelled
 					//ignore moving platforms for now
 					let target=core::mem::replace(&mut walk_state.target,TransientAcceleration::Reached);
-					set_acceleration(&mut state.body,&state.touching,&data.models,&data.hitbox_mesh,vec3::zero());
 					// check what the target was to see if it was invalid
 					match target{
 						//you are not supposed to reach a walk target which is already reached!
@@ -1874,7 +1844,7 @@ fn atomic_input_instruction(state:&mut PhysicsState,data:&PhysicsData,ins:TimedI
 		Instruction::Misc(MiscInstruction::PracticeFly)=>true,
 	};
 	if should_advance_body{
-		state.body.advance_time(state.time);
+		state.body=state.body.with_acceleration(state.acceleration(data)).extrapolated_body(state.time);
 	}
 
 	let mut b_refresh_walk_target=true;
@@ -1982,7 +1952,7 @@ fn atomic_input_instruction(state:&mut PhysicsState,data:&PhysicsData,ins:TimedI
 mod test{
 	use strafesnet_common::integer::{vec3::{self,int as int3},mat3};
 	use super::*;
-	fn test_collision_axis_aligned(relative_body:Body,expected_collision_time:Option<Time>){
+	fn test_collision_axis_aligned(relative_body:Trajectory,expected_collision_time:Option<Time>){
 		let h0=HitboxMesh::new(PhysicsMesh::unit_cube(),integer::Planar64Affine3::new(mat3::from_diagonal(int3(5,1,5)>>1),vec3::zero()));
 		let h1=StyleModifiers::roblox_bhop().calculate_mesh();
 		let hitbox_mesh=h1.transformed_mesh();
@@ -1991,7 +1961,7 @@ mod test{
 		let collision=minkowski.predict_collision_in(&relative_body,..);
 		assert_eq!(collision.map(|tup|relative_body.time+tup.1.into()),expected_collision_time,"Incorrect time of collision");
 	}
-	fn test_collision_rotated(relative_body:Body,expected_collision_time:Option<Time>){
+	fn test_collision_rotated(relative_body:Trajectory,expected_collision_time:Option<Time>){
 		let h0=HitboxMesh::new(PhysicsMesh::unit_cube(),
 			integer::Planar64Affine3::new(
 				Planar64Mat3::from_cols([
@@ -2009,13 +1979,13 @@ mod test{
 		let collision=minkowski.predict_collision_in(&relative_body,..);
 		assert_eq!(collision.map(|tup|relative_body.time+tup.1.into()),expected_collision_time,"Incorrect time of collision");
 	}
-	fn test_collision(relative_body:Body,expected_collision_time:Option<Time>){
+	fn test_collision(relative_body:Trajectory,expected_collision_time:Option<Time>){
 		test_collision_axis_aligned(relative_body,expected_collision_time);
 		test_collision_rotated(relative_body,expected_collision_time);
 	}
 	#[test]
 	fn test_collision_degenerate_straight_down(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,5,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2024,7 +1994,7 @@ mod test{
 	}
 	#[test]
 	fn test_collision_small_mv(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,5,0),
 			int3(0,-1,0)+(vec3::X>>32),
 			vec3::zero(),
@@ -2033,7 +2003,7 @@ mod test{
 	}
 	#[test]
 	fn test_collision_degenerate_east(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(3,5,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2042,7 +2012,7 @@ mod test{
 	}
 	#[test]
 	fn test_collision_degenerate_south(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,5,3),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2051,7 +2021,7 @@ mod test{
 	}
 	#[test]
 	fn test_collision_degenerate_west(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(-3,5,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2060,7 +2030,7 @@ mod test{
 	}
 	#[test]
 	fn test_collision_degenerate_north(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,5,-3),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2069,115 +2039,115 @@ mod test{
 	}
 	#[test]
 	fn test_collision_parabola_edge_east_from_west(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(3,3,0),
 			int3(100,-1,0),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_south_from_north(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,3,3),
 			int3(0,-1,100),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_west_from_east(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(-3,3,0),
 			int3(-100,-1,0),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_north_from_south(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,3,-3),
 			int3(0,-1,-100),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_north_from_ne(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,6,-7)>>1,
 			int3(-10,-1,1),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_north_from_nw(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,6,-7)>>1,
 			int3(10,-1,1),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_east_from_se(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(7,6,0)>>1,
 			int3(-1,-1,-10),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_east_from_ne(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(7,6,0)>>1,
 			int3(-1,-1,10),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_south_from_se(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,6,7)>>1,
 			int3(-10,-1,-1),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_south_from_sw(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,6,7)>>1,
 			int3(10,-1,-1),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_west_from_se(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(-7,6,0)>>1,
 			int3(1,-1,-10),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_parabola_edge_west_from_ne(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(-7,6,0)>>1,
 			int3(1,-1,10),
 			int3(0,-1,0),
 			Time::ZERO
-		).relative_to(&Body::ZERO).body(Time::from_secs(-1)),Some(Time::from_secs(0)));
+		).relative_to(&Trajectory::ZERO,Time::from_secs(-1)),Some(Time::from_secs(0)));
 	}
 	#[test]
 	fn test_collision_oblique(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,5,0),
 			int3(1,-64,2)>>6,// /64
 			vec3::zero(),
@@ -2186,7 +2156,7 @@ mod test{
 	}
 	#[test]
 	fn zoom_hit_nothing(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			int3(0,10,0),
 			int3(1,0,0),
 			int3(0,1,0),
@@ -2195,7 +2165,7 @@ mod test{
 	}
 	#[test]
 	fn already_inside_hit_nothing(){
-		test_collision(Body::new(
+		test_collision(Trajectory::new(
 			vec3::zero(),
 			int3(1,0,0),
 			int3(0,1,0),
@@ -2205,7 +2175,7 @@ mod test{
 	// overlap edges by 1 epsilon
 	#[test]
 	fn almost_miss_north(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(0,10,-7)>>1)+vec3::raw_xyz(0,0,1),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2214,7 +2184,7 @@ mod test{
 	}
 	#[test]
 	fn almost_miss_east(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(7,10,0)>>1)+vec3::raw_xyz(-1,0,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2223,7 +2193,7 @@ mod test{
 	}
 	#[test]
 	fn almost_miss_south(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(0,10,7)>>1)+vec3::raw_xyz(0,0,-1),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2232,7 +2202,7 @@ mod test{
 	}
 	#[test]
 	fn almost_miss_west(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(-7,10,0)>>1)+vec3::raw_xyz(1,0,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2242,7 +2212,7 @@ mod test{
 	// exactly miss edges
 	#[test]
 	fn exact_miss_north(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			int3(0,10,-7)>>1,
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2251,7 +2221,7 @@ mod test{
 	}
 	#[test]
 	fn exact_miss_east(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			int3(7,10,0)>>1,
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2260,7 +2230,7 @@ mod test{
 	}
 	#[test]
 	fn exact_miss_south(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			int3(0,10,7)>>1,
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2269,7 +2239,7 @@ mod test{
 	}
 	#[test]
 	fn exact_miss_west(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			int3(-7,10,0)>>1,
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2279,7 +2249,7 @@ mod test{
 	// miss edges by 1 epsilon
 	#[test]
 	fn narrow_miss_north(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(0,10,-7)>>1)-vec3::raw_xyz(0,0,1),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2288,7 +2258,7 @@ mod test{
 	}
 	#[test]
 	fn narrow_miss_east(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(7,10,0)>>1)-vec3::raw_xyz(-1,0,0),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2297,7 +2267,7 @@ mod test{
 	}
 	#[test]
 	fn narrow_miss_south(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(0,10,7)>>1)-vec3::raw_xyz(0,0,-1),
 			int3(0,-1,0),
 			vec3::zero(),
@@ -2306,7 +2276,7 @@ mod test{
 	}
 	#[test]
 	fn narrow_miss_west(){
-		test_collision_axis_aligned(Body::new(
+		test_collision_axis_aligned(Trajectory::new(
 			(int3(-7,10,0)>>1)-vec3::raw_xyz(1,0,0),
 			int3(0,-1,0),
 			vec3::zero(),
diff --git a/engine/session/src/session.rs b/engine/session/src/session.rs
index cb61e13e..a6b41ee6 100644
--- a/engine/session/src/session.rs
+++ b/engine/session/src/session.rs
@@ -57,7 +57,7 @@ pub enum SessionPlaybackInstruction{
 }
 
 pub struct FrameState{
-	pub body:physics::Body,
+	pub trajectory:physics::Trajectory,
 	pub camera:physics::PhysicsCamera,
 	pub time:PhysicsTime,
 }
@@ -76,9 +76,9 @@ impl Simulation{
 			physics,
 		}
 	}
-	pub fn get_frame_state(&self,time:SessionTime)->FrameState{
+	pub fn get_frame_state(&self,time:SessionTime,data:&PhysicsData)->FrameState{
 		FrameState{
-			body:self.physics.camera_body(),
+			trajectory:self.physics.camera_trajectory(data),
 			camera:self.physics.camera(),
 			time:self.timer.time(time),
 		}
@@ -187,9 +187,9 @@ impl Session{
 	}
 	pub fn get_frame_state(&self,time:SessionTime)->Option<FrameState>{
 		match &self.view_state{
-			ViewState::Play=>Some(self.simulation.get_frame_state(time)),
+			ViewState::Play=>Some(self.simulation.get_frame_state(time,&self.geometry_shared)),
 			ViewState::Replay(bot_id)=>self.replays.get(bot_id).map(|replay|
-				replay.simulation.get_frame_state(time)
+				replay.simulation.get_frame_state(time,&self.geometry_shared)
 			),
 		}
 	}
diff --git a/integration-testing/src/main.rs b/integration-testing/src/main.rs
index ef13197e..221f7ce4 100644
--- a/integration-testing/src/main.rs
+++ b/integration-testing/src/main.rs
@@ -71,16 +71,16 @@ fn segment_determinism(bot:strafesnet_snf::bot::Segment,physics_data:&PhysicsDat
 	for (i,ins) in bot.instructions.into_iter().enumerate(){
 		let state_deterministic=physics_deterministic.clone();
 		let state_filtered=physics_filtered.clone();
-		PhysicsContext::run_input_instruction(&mut physics_deterministic,&physics_data,ins.clone());
+		PhysicsContext::run_input_instruction(&mut physics_deterministic,physics_data,ins.clone());
 		match ins{
 			strafesnet_common::instruction::TimedInstruction{instruction:strafesnet_common::physics::Instruction::Idle,..}=>(),
 			other=>{
 				non_idle_count+=1;
 				// run
-				PhysicsContext::run_input_instruction(&mut physics_filtered,&physics_data,other.clone());
+				PhysicsContext::run_input_instruction(&mut physics_filtered,physics_data,other.clone());
 				// check if position matches
-				let b0=physics_deterministic.camera_body();
-				let b1=physics_filtered.camera_body();
+				let b0=physics_deterministic.camera_trajectory(physics_data);
+				let b1=physics_filtered.camera_trajectory(physics_data);
 				if b0.position!=b1.position{
 					let nanoseconds=start.elapsed().as_nanos() as u64;
 					println!("desync at instruction #{}",i);
diff --git a/integration-testing/src/test_scenes.rs b/integration-testing/src/test_scenes.rs
index d2008d01..cde90676 100644
--- a/integration-testing/src/test_scenes.rs
+++ b/integration-testing/src/test_scenes.rs
@@ -73,7 +73,6 @@ fn simultaneous_collision(){
 	let body=strafesnet_physics::physics::Body::new(
 		(vec3::int(5+2,0,0)>>1)+vec3::int(1,1,0),
 		vec3::int(-1,-1,0),
-		vec3::int(0,0,0),
 		Time::ZERO,
 	);
 	let mut physics=PhysicsState::new_with_body(body);
@@ -88,7 +87,6 @@ fn simultaneous_collision(){
 	let body=physics.body();
 	assert_eq!(body.position,vec3::int(5,0,0));
 	assert_eq!(body.velocity,vec3::int(0,0,0));
-	assert_eq!(body.acceleration,vec3::int(0,0,0));
 	assert_eq!(body.time,Time::from_secs(1));
 }
 #[test]
@@ -97,7 +95,6 @@ fn bug_3(){
 	let body=strafesnet_physics::physics::Body::new(
 		(vec3::int(5+2,0,0)>>1)+vec3::int(1,2,0),
 		vec3::int(-1,-1,0),
-		vec3::int(0,0,0),
 		Time::ZERO,
 	);
 	let mut physics=PhysicsState::new_with_body(body);
@@ -112,6 +109,5 @@ fn bug_3(){
 	let body=physics.body();
 	assert_eq!(body.position,vec3::int(5+2,0,0)>>1);
 	assert_eq!(body.velocity,vec3::int(0,0,0));
-	assert_eq!(body.acceleration,vec3::int(0,0,0));
 	assert_eq!(body.time,Time::from_secs(2));
 }
diff --git a/integration-testing/src/tests.rs b/integration-testing/src/tests.rs
index bcc64b0c..7b8cc3b3 100644
--- a/integration-testing/src/tests.rs
+++ b/integration-testing/src/tests.rs
@@ -22,7 +22,6 @@ fn physics_bug_2()->Result<(),ReplayError>{
 	let body=strafesnet_physics::physics::Body::new(
 		vec3::raw_xyz(555690659654,1490485868773,1277783839382),
 		vec3::int(0,0,0),
-		vec3::int(0,-100,0),
 		Time::ZERO,
 	);
 	let mut physics=PhysicsState::new_with_body(body);
@@ -66,7 +65,6 @@ fn physics_bug_3()->Result<(),ReplayError>{
 		// Actual bug 3 repro
 		vec3::raw_xyz(-2505538624455,3357963283914,557275711118),
 		vec3::raw_xyz(204188283920,-282280474198,166172785440),
-		vec3::raw_xyz(0,-429496729600,0),
 		Time::ZERO,
 	);
 	let mut physics=PhysicsState::new_with_body(body);
-- 
2.49.1


From 1a958a11b4830a55c112a0efd988073ce8d5631a Mon Sep 17 00:00:00 2001
From: Rhys Lloyd <krakow20@gmail.com>
Date: Tue, 27 Jan 2026 09:02:26 -0800
Subject: [PATCH 3/3] fix bugs

---
 engine/physics/src/physics.rs | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/engine/physics/src/physics.rs b/engine/physics/src/physics.rs
index 8275abf0..848eb23c 100644
--- a/engine/physics/src/physics.rs
+++ b/engine/physics/src/physics.rs
@@ -499,6 +499,23 @@ enum MoveState{
 	Fly,
 }
 impl MoveState{
+	//call this after state.move_state is changed
+	fn acceleration(&self,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState)->Planar64Vec3{
+		match self{
+			MoveState::Fly=>vec3::zero(),
+			MoveState::Air
+			|MoveState::Water
+			=>{
+				// calculate base acceleration
+				let base_acceleration=touching.base_acceleration(models,style,camera,input_state);
+				// constrain_acceleration clips according to contacts
+				touching.constrain_acceleration(models,hitbox_mesh,base_acceleration)
+			},
+			MoveState::Walk(walk_state)
+			|MoveState::Ladder(walk_state)
+			=>walk_state.target.acceleration(),
+		}
+	}
 	//function to coerce &mut self into &self
 	fn apply_to_body(&self,body:&mut Body,touching:&TouchingState,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,style:&StyleModifiers,camera:&PhysicsCamera,input_state:&InputState){
 		match self{
@@ -932,8 +949,7 @@ impl PhysicsState{
 		self.move_state.apply_input_and_body(&mut self.body,&self.touching,&data.models,&data.hitbox_mesh,&self.style,&self.camera,&self.input_state);
 	}
 	fn acceleration(&self,data:&PhysicsData)->Planar64Vec3{
-		let base_acceleration=self.touching.base_acceleration(&data.models,&self.style,&self.camera,&self.input_state);
-		self.touching.constrain_acceleration(&data.models,&data.hitbox_mesh,base_acceleration)
+		self.move_state.acceleration(&self.touching,&data.models,&data.hitbox_mesh,&self.style,&self.camera,&self.input_state)
 	}
 	//state mutated on collision:
 	//Accelerator
-- 
2.49.1