Compress CFrames using axis-angle representation

zap/src/config.rs

@@ -181,7 +181,7 @@ impl<'src> Ty<'src> {
 			Self::Color3 => (12, Some(12)),
 			Self::Vector3 => (12, Some(12)),
 			Self::AlignedCFrame => (13, Some(13)),
-			Self::CFrame => (48, Some(48)),
+			Self::CFrame => (24, Some(24)),
 			Self::Unknown => (0, None),
 		}
 	}

zap/src/irgen/des.rs

@@ -281,18 +281,44 @@ 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 branch is required.
 
+				// if angle ~= 0 then
+				//		value = CFrame.fromAxisAngle(axisangle, angle) + pos
+				// else
+				//		value = CFrame.new(pos)
+				// end
+
+				self.push_stmt(Stmt::If(Expr::Neq(Box::new("angle".into()), Box::new("0".into()))));
 				self.push_assign(
-					into,
-					Expr::Call(
-						Box::new(Var::from("CFrame").nindex("fromMatrix")),
-						None,
-						vec!["pos".into(), "vX".into(), "vY".into(), "vZ".into()],
+					into.clone(),
+					Expr::Add(
+						Box::new(Expr::Call(
+							Box::new(Var::from("CFrame").nindex("fromAxisAngle")),
+							None,
+							vec!["axisangle".into(), "angle".into()],
+						)),
+						Box::new("pos".into()),
 					),
 				);
+				self.push_stmt(Stmt::Else);
+				self.push_assign(
+					into,
+					Expr::Call(Box::new(Var::from("CFrame").nindex("new")), None, vec!["pos".into()]),
+				);
+				self.push_stmt(Stmt::End);
 			}
 		}
 	}

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}\")")),