1 files changed, 112 insertions, 0 deletions
diff --git a/src/dynamics/joint/joint.rs b/src/dynamics/joint/joint.rs
new file mode 100644
index 0000000..074f802
--- /dev/null
+++ b/src/dynamics/joint/joint.rs
@@ -0,0 +1,112 @@
+#[cfg(feature = "dim3")]
+use crate::dynamics::RevoluteJoint;
+use crate::dynamics::{BallJoint, FixedJoint, JointHandle, PrismaticJoint, RigidBodyHandle};
+
+#[derive(Copy, Clone)]
+#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+/// An enum grouping all possible types of joints.
+pub enum JointParams {
+    /// A Ball joint that removes all relative linear degrees of freedom between the affected bodies.
+    BallJoint(BallJoint),
+    /// A fixed joint that removes all relative degrees of freedom between the affected bodies.
+    FixedJoint(FixedJoint),
+    /// A prismatic joint that removes all degrees of degrees of freedom between the affected
+    /// bodies except for the translation along one axis.
+    PrismaticJoint(PrismaticJoint),
+    #[cfg(feature = "dim3")]
+    /// A revolute joint that removes all degrees of degrees of freedom between the affected
+    /// bodies except for the translation along one axis.
+    RevoluteJoint(RevoluteJoint),
+}
+
+impl JointParams {
+    /// An integer identifier for each type of joint.
+    pub fn type_id(&self) -> usize {
+        match self {
+            JointParams::BallJoint(_) => 0,
+            JointParams::FixedJoint(_) => 1,
+            JointParams::PrismaticJoint(_) => 2,
+            #[cfg(feature = "dim3")]
+            JointParams::RevoluteJoint(_) => 3,
+        }
+    }
+
+    /// Gets a reference to the underlying ball joint, if `self` is one.
+    pub fn as_ball_joint(&self) -> Option<&BallJoint> {
+        if let JointParams::BallJoint(j) = self {
+            Some(j)
+        } else {
+            None
+        }
+    }
+
+    /// Gets a reference to the underlying fixed joint, if `self` is one.
+    pub fn as_fixed_joint(&self) -> Option<&FixedJoint> {
+        if let JointParams::FixedJoint(j) = self {
+            Some(j)
+        } else {
+            None
+        }
+    }
+
+    /// Gets a reference to the underlying prismatic joint, if `self` is one.
+    pub fn as_prismatic_joint(&self) -> Option<&PrismaticJoint> {
+        if let JointParams::PrismaticJoint(j) = self {
+            Some(j)
+        } else {
+            None
+        }
+    }
+
+    /// Gets a reference to the underlying revolute joint, if `self` is one.
+    #[cfg(feature = "dim3")]
+    pub fn as_revolute_joint(&self) -> Option<&RevoluteJoint> {
+        if let JointParams::RevoluteJoint(j) = self {
+            Some(j)
+        } else {
+            None
+        }
+    }
+}
+
+impl From<BallJoint> for JointParams {
+    fn from(j: BallJoint) -> Self {
+        JointParams::BallJoint(j)
+    }
+}
+
+impl From<FixedJoint> for JointParams {
+    fn from(j: FixedJoint) -> Self {
+        JointParams::FixedJoint(j)
+    }
+}
+
+#[cfg(feature = "dim3")]
+impl From<RevoluteJoint> for JointParams {
+    fn from(j: RevoluteJoint) -> Self {
+        JointParams::RevoluteJoint(j)
+    }
+}
+
+impl From<PrismaticJoint> for JointParams {
+    fn from(j: PrismaticJoint) -> Self {
+        JointParams::PrismaticJoint(j)
+    }
+}
+
+#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+/// A joint attached to two bodies.
+pub struct Joint {
+    /// Handle to the first body attached to this joint.
+    pub body1: RigidBodyHandle,
+    /// Handle to the second body attached to this joint.
+    pub body2: RigidBodyHandle,
+    // A joint needs to know its handle to simplify its removal.
+    pub(crate) handle: JointHandle,
+    #[cfg(feature = "parallel")]
+    pub(crate) constraint_index: usize,
+    #[cfg(feature = "parallel")]
+    pub(crate) position_constraint_index: usize,
+    /// The joint geometric parameters and impulse.
+    pub params: JointParams,
+}