Compress CFrames using axis-angle representation

zap/src/config.rs

@@ -101,7 +101,7 @@ impl<'src> Ty<'src> {
 			Self::Color3 => Some(NumTy::U8.size() * 3),
 			Self::Vector3 => Some(NumTy::F32.size() * 3),
 			Self::AlignedCFrame => Some(NumTy::U8.size() + NumTy::F32.size() * 3),
-			Self::CFrame => Some(NumTy::F32.size() * 12),
+			Self::CFrame => Some(NumTy::F32.size() * 6),
 			Self::Boolean => Some(1),
 			Self::Opt(ty) => ty.max_size(config, recursed).map(|size| size + 1),
 			Self::Str(len) => len.max().map(|len| len as usize),

zap/src/irgen/des.rs

@@ -281,16 +281,41 @@ impl Des {
 			}
 			Ty::CFrame => {
 				self.push_local("pos", Some(self.readvector3()));
-				self.push_local("vX", Some(self.readvector3()));
-				self.push_local("vY", Some(self.readvector3()));
-				self.push_local("vZ", Some(self.readvector3()));
+				self.push_local("axisangle", Some(self.readvector3()));
+				self.push_local(
+					"angle",
+					Some(Expr::Var(Box::new(Var::NameIndex(
+						Box::new("axisangle".into()),
+						"Magnitude".into(),
+					)))),
+				);
+
+				// We don't need to convert the axis back to a unit vector as the constructor does that for us
+				// The angle is the magnitude of the axis vector
+				// If the magnitude is 0, there is no rotation, so just make a cframe at the right position.
+				// 	Trying to use fromAxisAngle in this situation gives NAN which is not ideal, so the and/or clause is required.
+
+				// value = angle ~= 0 and CFrame.fromAxisAngle(axisangle, angle) + pos or CFrame.new(pos)
 
 				self.push_assign(
 					into,
-					Expr::Call(
-						Box::new(Var::from("CFrame").nindex("fromMatrix")),
-						None,
-						vec!["pos".into(), "vX".into(), "vY".into(), "vZ".into()],
+					Expr::Or(
+						Box::new(Expr::And(
+							Box::new(Expr::Neq(Box::new("angle".into()), Box::new("0".into()))),
+							Box::new(Expr::Add(
+								Box::new(Expr::Call(
+									Box::new(Var::from("CFrame").nindex("fromAxisAngle")),
+									None,
+									vec!["axisangle".into(), "angle".into()],
+								)),
+								Box::new("pos".into()),
+							)),
+						)),
+						Box::new(Expr::Call(
+							Box::new(Var::from("CFrame").nindex("new")),
+							None,
+							vec!["pos".into()],
+						)),
 					),
 				);
 			}

zap/src/irgen/mod.rs

@@ -249,6 +249,7 @@ pub trait Gen {
 #[derive(Debug, Clone)]
 pub enum Stmt {
 	Local(&'static str, Option<Expr>),
+	LocalTuple(Vec<&'static str>, Option<Expr>),
 	Assign(Var, Expr),
 	Error(String),
 	Assert(Expr, Option<String>),

zap/src/irgen/ser.rs

@@ -266,10 +266,21 @@ impl Ser {
 			}
 
 			Ty::CFrame => {
+				// local axis, angle = Value:ToAxisAngle()
+				self.push_stmt(Stmt::LocalTuple(
+					vec!["axis", "angle"],
+					Some(Expr::Call(from.clone().into(), Some("ToAxisAngle".into()), vec![])),
+				));
+
+				// axis = axis * angle
+				// store the angle into the axis, as it is a unit vector, so the magnitude can be used to encode a number
+				self.push_stmt(Stmt::Assign(
+					Var::Name("axis".into()),
+					Expr::Mul(Box::new("axis".into()), Box::new("angle".into())),
+				));
+
 				self.push_ty(&Ty::Vector3, from.clone().nindex("Position"));
-				self.push_ty(&Ty::Vector3, from.clone().nindex("XVector"));
-				self.push_ty(&Ty::Vector3, from.clone().nindex("YVector"));
-				self.push_ty(&Ty::Vector3, from.clone().nindex("ZVector"));
+				self.push_ty(&Ty::Vector3, "axis".into());
 			}
 
 			Ty::Boolean => self.push_writeu8(from_expr.and(1.0.into()).or(0.0.into())),

zap/src/output/luau/mod.rs

@@ -31,6 +31,22 @@ pub trait Output {
 					self.push_line(&format!("local {name}"));
 				}
 			}
+			Stmt::LocalTuple(var, expr) => {
+				let mut items = String::new();
+
+				for (i, exp) in var.iter().enumerate() {
+					if i != 0 {
+						items.push_str(", ");
+					}
+					items.push_str(exp)
+				}
+
+				if let Some(expr) = expr {
+					self.push_line(&format!("local {items} = {expr}"));
+				} else {
+					self.push_line(&format!("local {items}"));
+				}
+			}
 
 			Stmt::Assign(var, expr) => self.push_line(&format!("{var} = {expr}")),
 			Stmt::Error(msg) => self.push_line(&format!("error(\"{msg}\")")),