1 files changed, 40 insertions, 0 deletions
diff --git a/src/dynamics/mass_properties_cylinder.rs b/src/dynamics/mass_properties_cylinder.rs
new file mode 100644
index 0000000..66a1343
--- /dev/null
+++ b/src/dynamics/mass_properties_cylinder.rs
@@ -0,0 +1,40 @@
+use crate::dynamics::MassProperties;
+#[cfg(feature = "dim3")]
+use crate::geometry::Capsule;
+use crate::math::{Point, PrincipalAngularInertia, Rotation, Vector};
+
+impl MassProperties {
+    pub(crate) fn cylinder_y_volume_unit_inertia(
+        half_height: f32,
+        radius: f32,
+    ) -> (f32, PrincipalAngularInertia<f32>) {
+        #[cfg(feature = "dim2")]
+        {
+            Self::cuboid_volume_unit_inertia(Vector::new(radius, half_height))
+        }
+
+        #[cfg(feature = "dim3")]
+        {
+            let volume = half_height * radius * radius * std::f32::consts::PI * 2.0;
+            let sq_radius = radius * radius;
+            let sq_height = half_height * half_height * 4.0;
+            let off_principal = (sq_radius * 3.0 + sq_height) / 12.0;
+
+            let inertia = Vector::new(off_principal, sq_radius / 2.0, off_principal);
+            (volume, inertia)
+        }
+    }
+
+    #[cfg(feature = "dim3")]
+    pub(crate) fn from_cylinder(density: f32, half_height: f32, radius: f32) -> Self {
+        let (cyl_vol, cyl_unit_i) = Self::cylinder_y_volume_unit_inertia(half_height, radius);
+        let cyl_mass = cyl_vol * density;
+
+        Self::with_principal_inertia_frame(
+            Point::origin(),
+            cyl_mass,
+            cyl_unit_i * cyl_mass,
+            Rotation::identity(),
+        )
+    }
+}