push solve!

Cargo.lock

@@ -2107,6 +2107,7 @@ checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 name = "strafe-client"
 version = "0.10.5"
 dependencies = [
+ "arrayvec",
  "bytemuck",
  "configparser",
  "ddsfile",

Cargo.toml

@@ -15,6 +15,7 @@ source = ["dep:strafesnet_deferred_loader", "dep:strafesnet_bsp_loader"]
 roblox = ["dep:strafesnet_deferred_loader", "dep:strafesnet_rbx_loader"]
 
 [dependencies]
+arrayvec = "0.7.6"
 bytemuck = { version = "1.13.1", features = ["derive"] }
 configparser = "3.0.2"
 ddsfile = "0.5.1"

src/main.rs

@@ -5,6 +5,7 @@ mod worker;
 mod physics;
 mod graphics;
 mod settings;
+mod push_solve;
 mod face_crawler;
 mod compat_worker;
 mod model_physics;

src/physics.rs

@@ -766,23 +766,31 @@ impl TouchingState{
 		a
 	}
 	fn constrain_velocity(&self,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,velocity:&mut Planar64Vec3){
-		//TODO: trey push solve
+		let contacts=self.contacts.iter().map(|contact|{
-		for contact in &self.contacts{
 			let n=contact_normal(models,hitbox_mesh,contact);
-			let d=n.dot(*velocity);
+			crate::push_solve::Contact{
-			if d.is_negative(){
+				position:Planar64Vec3::ZERO,
-				*velocity-=(n*d/n.length_squared()).divide().fix_1();
+				velocity:n,
+				normal:n,
 			}
+		}).collect();
+		match crate::push_solve::push_solve(&contacts,*velocity){
+			Some(new_velocity)=>*velocity=new_velocity,
+			None=>println!("Algorithm silently failing :)"),
 		}
 	}
 	fn constrain_acceleration(&self,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,acceleration:&mut Planar64Vec3){
-		//TODO: trey push solve
+		let contacts=self.contacts.iter().map(|contact|{
-		for contact in &self.contacts{
 			let n=contact_normal(models,hitbox_mesh,contact);
-			let d=n.dot(*acceleration);
+			crate::push_solve::Contact{
-			if d.is_negative(){
+				position:Planar64Vec3::ZERO,
-				*acceleration-=(n*d/n.length_squared()).divide().fix_1();
+				velocity:n,
+				normal:n,
 			}
+		}).collect();
+		match crate::push_solve::push_solve(&contacts,*acceleration){
+			Some(new_acceleration)=>*acceleration=new_acceleration,
+			None=>println!("Algorithm silently failing :)"),
 		}
 	}
 	fn predict_collision_end(&self,collector:&mut instruction::InstructionCollector<PhysicsInternalInstruction>,models:&PhysicsModels,hitbox_mesh:&HitboxMesh,body:&Body,time:Time){

src/push_solve.rs

@@ -0,0 +1,339 @@
+use strafesnet_common::integer::{Planar64,Planar64Vec3};
+
+// This algorithm is based on Lua code
+// written by Trey Reynolds in 2021
+
+// 1/2^10
+const EPSILON:Planar64=Planar64::raw(1<<(32-10));
+
+// A stack-allocated variable-size list that holds up to 4 elements
+// Direct references are used instead of indices i0, i1, i2, i3
+type Conts<'a>=arrayvec::ArrayVec<&'a Contact,4>;
+
+struct Ray{
+	origin:Planar64Vec3,
+	direction:Planar64Vec3,
+}
+impl Ray{
+	fn extrapolate(&self,t:Planar64)->Planar64Vec3{
+		self.origin+self.direction*t
+	}
+}
+
+/// Information about a contact restriction
+pub struct Contact{
+	pub position:Planar64Vec3,
+	pub velocity:Planar64Vec3,
+	pub normal:Planar64Vec3,
+}
+impl Contact{
+	fn relative_to(&self,point:Planar64Vec3)->Self{
+		Self{
+			position:self.position-point,
+			velocity:self.velocity,
+			normal:self.normal,
+		}
+	}
+	fn relative_dot(&self,direction:Planar64Vec3)->Planar64{
+		(direction-self.velocity).dot(self.normal)
+	}
+	/// Calculate the time of intersection. (previously get_touch_time)
+	fn solve(&self,ray:&Ray)->Planar64{
+		(self.position-ray.origin).dot(self.normal)/(ray.direction-self.velocity).dot(self.normal)
+	}
+}
+
+//note that this is horrible with fixed point arithmetic
+fn solve1(c0:&Contact)->Option<Planar64Vec3>{
+	let det=c0.normal.dot(c0.velocity);
+	if det.get().abs()<EPSILON.get(){
+		return None;
+	}
+	let d0=c0.normal.dot(c0.position);
+	Some(c0.normal*d0/det)
+}
+fn solve2(c0:&Contact,c1:&Contact)->Option<Planar64Vec3>{
+	let u0_u1=c0.velocity.cross(c1.velocity);
+	let n0_n1=c0.normal.cross(c1.normal);
+	let det=u0_u1.dot(n0_n1);
+	if det.get().abs()<EPSILON.get(){
+		return None;
+	}
+	let d0=c0.normal.dot(c0.position);
+	let d1=c1.normal.dot(c1.position);
+	Some((c1.normal.cross(u0_u1)*d0+u0_u1.cross(c0.normal)*d1)/det)
+}
+fn solve3(c0:&Contact,c1:&Contact,c2:&Contact)->Option<Planar64Vec3>{
+	let n0_n1=c0.normal.cross(c1.normal);
+	let det=c2.normal.dot(n0_n1);
+	if det.get().abs()<EPSILON.get(){
+		return None;
+	}
+	let d0=c0.normal.dot(c0.position);
+	let d1=c1.normal.dot(c1.position);
+	let d2=c2.normal.dot(c2.position);
+	Some((c1.normal.cross(c2.normal)*d0+c2.normal.cross(c0.normal)*d1+c0.normal.cross(c1.normal)*d2)/det)
+}
+
+fn decompose1(point:Planar64Vec3,u0:Planar64Vec3)->Option<Planar64>{
+	let det=u0.dot(u0);
+	if det==Planar64::ZERO{
+		return None;
+	}
+	let s0=u0.dot(point)/det;
+	Some(s0)
+}
+fn decompose2(point:Planar64Vec3,u0:Planar64Vec3,u1:Planar64Vec3)->Option<(Planar64,Planar64)>{
+	let u0_u1=u0.cross(u1);
+	let det=u0_u1.dot(u0_u1);
+	if det==Planar64::ZERO{
+		return None;
+	}
+	let s0=u0_u1.dot(point.cross(u1))/det;
+	let s1=u0_u1.dot(u0.cross(point))/det;
+	Some((s0,s1))
+}
+fn decompose3(point:Planar64Vec3,u0:Planar64Vec3,u1:Planar64Vec3,u2:Planar64Vec3)->Option<(Planar64,Planar64,Planar64)>{
+	let det=u0.cross(u1).dot(u2);
+	if det==Planar64::ZERO{
+		return None;
+	}
+	let s0=point.cross(u1).dot(u2)/det;
+	let s1=u0.cross(point).dot(u2)/det;
+	let s2=u0.cross(u1).dot(point)/det;
+	Some((s0,s1,s2))
+}
+
+fn is_space_enclosed_2(
+	a:Planar64Vec3,
+	b:Planar64Vec3,
+)->bool{
+	a.cross(b)==Planar64Vec3::ZERO
+	&&a.dot(b)<Planar64::ZERO
+}
+fn is_space_enclosed_3(
+	a:Planar64Vec3,
+	b:Planar64Vec3,
+	c:Planar64Vec3
+)->bool{
+	a.cross(b).dot(c)==Planar64::ZERO
+	&&{
+		let det_abac=a.cross(b).dot(a.cross(c));
+		let det_abbc=a.cross(b).dot(b.cross(c));
+		let det_acbc=a.cross(c).dot(b.cross(c));
+		return det_abac*det_abbc<=Planar64::ZERO
+			&& det_abbc*det_acbc<=Planar64::ZERO
+			&&-det_acbc*det_abac<=Planar64::ZERO
+			||is_space_enclosed_2(a,b)
+			||is_space_enclosed_2(a,c)
+			||is_space_enclosed_2(b,c)
+	}
+}
+fn is_space_enclosed_4(
+	a:Planar64Vec3,
+	b:Planar64Vec3,
+	c:Planar64Vec3,
+	d:Planar64Vec3,
+)->bool{
+	let det_abc=a.cross(b).dot(c);
+	let det_abd=a.cross(b).dot(d);
+	let det_acd=a.cross(c).dot(d);
+	let det_bcd=b.cross(c).dot(d);
+	return det_abc*det_abd<Planar64::ZERO
+		&&-det_abc*det_acd<Planar64::ZERO
+		&& det_abd*det_acd<Planar64::ZERO
+		&& det_abc*det_bcd<Planar64::ZERO
+		&&-det_abd*det_bcd<Planar64::ZERO
+		&& det_acd*det_bcd<Planar64::ZERO
+		||is_space_enclosed_3(a,b,c)
+		||is_space_enclosed_3(a,b,d)
+		||is_space_enclosed_3(a,c,d)
+		||is_space_enclosed_3(b,c,d)
+}
+
+const fn get_push_ray_0(point:Planar64Vec3)->Option<Ray>{
+	Some(Ray{origin:point,direction:Planar64Vec3::ZERO})
+}
+fn get_push_ray_1(point:Planar64Vec3,c0:&Contact)->Option<Ray>{
+	let direction=solve1(c0)?;
+	let s0=decompose1(direction,c0.velocity)?;
+	if s0<Planar64::ZERO{
+		return None;
+	}
+	let origin=point+solve1(
+		&c0.relative_to(point),
+	)?;
+	Some(Ray{origin,direction})
+}
+fn get_push_ray_2(point:Planar64Vec3,c0:&Contact,c1:&Contact)->Option<Ray>{
+	let direction=solve2(c0,c1)?;
+	let (s0,s1)=decompose2(direction,c0.velocity,c1.velocity)?;
+	if s0<Planar64::ZERO||s1<Planar64::ZERO{
+		return None;
+	}
+	let origin=point+solve2(
+		&c0.relative_to(point),
+		&c1.relative_to(point),
+	)?;
+	Some(Ray{origin,direction})
+}
+fn get_push_ray_3(point:Planar64Vec3,c0:&Contact,c1:&Contact,c2:&Contact)->Option<Ray>{
+	let direction=solve3(c0,c1,c2)?;
+	let (s0,s1,s2)=decompose3(direction,c0.velocity,c1.velocity,c2.velocity)?;
+	if s0<Planar64::ZERO||s1<Planar64::ZERO||s2<Planar64::ZERO{
+		return None;
+	}
+	let origin=point+solve3(
+		&c0.relative_to(point),
+		&c1.relative_to(point),
+		&c2.relative_to(point),
+	)?;
+	Some(Ray{origin,direction})
+}
+
+const fn get_best_push_ray_and_conts_0<'a>(point:Planar64Vec3)->Option<(Ray,Conts<'a>)>{
+	match get_push_ray_0(point){
+		Some(ray)=>Some((ray,Conts::new_const())),
+		None=>None,
+	}
+}
+fn get_best_push_ray_and_conts_1(point:Planar64Vec3,c0:&Contact)->Option<(Ray,Conts)>{
+	get_push_ray_1(point,c0)
+		.map(|ray|(ray,Conts::from_iter([c0])))
+}
+fn get_best_push_ray_and_conts_2<'a>(point:Planar64Vec3,c0:&'a Contact,c1:&'a Contact)->Option<(Ray,Conts<'a>)>{
+	if is_space_enclosed_2(c0.normal,c1.normal){
+		return None;
+	}
+	if let Some(ray)=get_push_ray_2(point,c0,c1){
+		return Some((ray,Conts::from_iter([c0,c1])));
+	}
+	if let Some(ray)=get_push_ray_1(point,c0){
+		if Planar64::ZERO<=c1.relative_dot(ray.direction){
+			return Some((ray,Conts::from_iter([c0])));
+		}
+	}
+	return None;
+}
+fn get_best_push_ray_and_conts_3<'a>(point:Planar64Vec3,c0:&'a Contact,c1:&'a Contact,c2:&'a Contact)->Option<(Ray,Conts<'a>)>{
+	if is_space_enclosed_3(c0.normal,c1.normal,c2.normal){
+		return None;
+	}
+	if let Some(ray)=get_push_ray_3(point,c0,c1,c2){
+		return Some((ray,Conts::from_iter([c0,c1,c2])));
+	}
+	if let Some(ray)=get_push_ray_2(point,c0,c1){
+		if Planar64::ZERO<=c2.relative_dot(ray.direction){
+			return Some((ray,Conts::from_iter([c0,c1])));
+		}
+	}
+	if let Some(ray)=get_push_ray_2(point,c0,c2){
+		if Planar64::ZERO<=c1.relative_dot(ray.direction){
+			return Some((ray,Conts::from_iter([c0,c2])));
+		}
+	}
+	if let Some(ray)=get_push_ray_1(point,c0){
+		if Planar64::ZERO<=c1.relative_dot(ray.direction)
+		 &&Planar64::ZERO<=c2.relative_dot(ray.direction){
+			return Some((ray,Conts::from_iter([c0])));
+		}
+	}
+	return None;
+}
+fn get_best_push_ray_and_conts_4<'a>(point:Planar64Vec3,c0:&'a Contact,c1:&'a Contact,c2:&'a Contact,c3:&'a Contact)->Option<(Ray,Conts<'a>)>{
+	if is_space_enclosed_4(c0.normal,c1.normal,c2.normal,c3.normal){
+		return None;
+	}
+
+	let (ray012,conts012)=get_best_push_ray_and_conts_3(point,c0,c1,c2)?;
+	let (ray013,conts013)=get_best_push_ray_and_conts_3(point,c0,c1,c3)?;
+	let (ray023,conts023)=get_best_push_ray_and_conts_3(point,c0,c2,c3)?;
+
+	let err012=c3.relative_dot(ray012.direction);
+	let err013=c2.relative_dot(ray013.direction);
+	let err023=c1.relative_dot(ray023.direction);
+
+	let best_err=err012.max(err013).max(err023);
+
+	if best_err==err012{
+		return Some((ray012,conts012))
+	}else if best_err==err013{
+		return Some((ray013,conts013))
+	}else if best_err==err023{
+		return Some((ray023,conts023))
+	}
+	unreachable!()
+}
+
+fn get_best_push_ray_and_conts<'a>(
+	point:Planar64Vec3,
+	conts:Conts<'a>,
+)->Option<(Ray,Conts<'a>)>{
+	match conts.as_slice(){
+		&[c0,c1,c2,c3]=>get_best_push_ray_and_conts_4(point,c0,c1,c2,c3),
+		&[c0,c1,c2]=>get_best_push_ray_and_conts_3(point,c0,c1,c2),
+		&[c0,c1]=>get_best_push_ray_and_conts_2(point,c0,c1),
+		&[c0]=>get_best_push_ray_and_conts_1(point,c0),
+		&[]=>get_best_push_ray_and_conts_0(point),
+		_=>unreachable!(),
+	}
+}
+
+fn get_first_touch<'a>(contacts:&'a Vec<Contact>,ray:&Ray,conts:&Conts)->Option<(Planar64,&'a Contact)>{
+	contacts.iter()
+		.filter(|&contact|
+			!conts.iter().any(|&c|std::ptr::eq(c,contact))
+			&&contact.relative_dot(ray.direction)< -EPSILON
+		)
+		.map(|contact|(contact.solve(ray),contact))
+		.min_by_key(|&(t,_)|t)
+}
+
+pub fn push_solve(contacts:&Vec<Contact>,point:Planar64Vec3)->Option<Planar64Vec3>{
+	let (mut ray,mut conts)=get_best_push_ray_and_conts_0(point)?;
+	loop{
+		let (next_t,next_cont)=match get_first_touch(contacts,&ray,&conts){
+			Some((t,conts))=>(t,conts),
+			None=>return Some(ray.origin),
+		};
+
+		if Planar64::ZERO<=next_t{
+			return Some(ray.origin);
+		}
+
+		//push_front
+		if conts.len()==conts.capacity(){
+			//this is a dead case, new_conts never has more than 3 elements
+			conts.rotate_right(1);
+			conts[0]=next_cont;
+		}else{
+			conts.push(next_cont);
+			conts.rotate_right(1);
+		}
+
+		let meet_point=ray.extrapolate(next_t);
+		match get_best_push_ray_and_conts(meet_point,conts){
+			Some((new_ray,new_conts))=>(ray,conts)=(new_ray,new_conts),
+			None=>return Some(meet_point),
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests{
+	use super::*;
+	#[test]
+	fn test_push_solve(){
+		let contacts=vec![
+			Contact{
+				position:Planar64Vec3::ZERO,
+				velocity:Planar64Vec3::Y,
+				normal:Planar64Vec3::Y,
+			}
+		];
+		assert_eq!(
+			Some(Planar64Vec3::ZERO),
+			push_solve(&contacts,Planar64Vec3::NEG_Y)
+		);
+	}
+}