Allow disabling colliders, rigid-bodies and impulse joints

src/dynamics/joint/generic_joint.rs

@@ -5,6 +5,7 @@ use crate::utils::{WBasis, WReal};
 
 #[cfg(feature = "dim3")]
 use crate::dynamics::SphericalJoint;
+use crate::geometry::ColliderEnabled;
 
 #[cfg(feature = "dim3")]
 bitflags::bitflags! {
@@ -182,6 +183,19 @@ impl JointMotor {
     }
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
+/// Enum indicating whether or not a joint is enabled.
+pub enum JointEnabled {
+    /// The joint is enabled.
+    Enabled,
+    /// The joint wasn’t disabled by the user explicitly but it is attached to
+    /// a disabled rigid-body.
+    DisabledByAttachedBody,
+    /// The joint is disabled by the user explicitly.
+    Disabled,
+}
+
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
 #[derive(Copy, Clone, Debug, PartialEq)]
 /// A generic joint.
@@ -208,6 +222,8 @@ pub struct GenericJoint {
     pub motors: [JointMotor; SPATIAL_DIM],
     /// Are contacts between the attached rigid-bodies enabled?
     pub contacts_enabled: bool,
+    /// Whether or not the joint is enabled.
+    pub enabled: JointEnabled,
 }
 
 impl Default for GenericJoint {
@@ -222,6 +238,7 @@ impl Default for GenericJoint {
             limits: [JointLimits::default(); SPATIAL_DIM],
             motors: [JointMotor::default(); SPATIAL_DIM],
             contacts_enabled: true,
+            enabled: JointEnabled::Enabled,
         }
     }
 }
@@ -260,6 +277,27 @@ impl GenericJoint {
         }
     }
 
+    /// Is this joint enabled?
+    pub fn is_enabled(&self) -> bool {
+        self.enabled == JointEnabled::Enabled
+    }
+
+    /// Set whether this joint is enabled or not.
+    pub fn set_enabled(&mut self, enabled: bool) {
+        match self.enabled {
+            JointEnabled::Enabled | JointEnabled::DisabledByAttachedBody => {
+                if !enabled {
+                    self.enabled = JointEnabled::Disabled;
+                }
+            }
+            JointEnabled::Disabled => {
+                if enabled {
+                    self.enabled = JointEnabled::Enabled;
+                }
+            }
+        }
+    }
+
     /// Add the specified axes to the set of axes locked by this joint.
     pub fn lock_axes(&mut self, axes: JointAxesMask) -> &mut Self {
         self.locked_axes |= axes;