First public release of Rapier.v0.1.0

1 files changed, 33 insertions, 0 deletions

diff --git a/src/dynamics/mass_properties_cuboid.rs b/src/dynamics/mass_properties_cuboid.rs
new file mode 100644
index 0000000..2d870cf
--- /dev/null
+++ b/src/dynamics/mass_properties_cuboid.rs
@@ -0,0 +1,33 @@
+use crate::dynamics::MassProperties;
+use crate::math::{Point, PrincipalAngularInertia, Vector};
+
+impl MassProperties {
+    pub(crate) fn cuboid_volume_unit_inertia(
+        half_extents: Vector<f32>,
+    ) -> (f32, PrincipalAngularInertia<f32>) {
+        #[cfg(feature = "dim2")]
+        {
+            let volume = half_extents.x * half_extents.y * 4.0;
+            let ix = (half_extents.x * half_extents.x) / 3.0;
+            let iy = (half_extents.y * half_extents.y) / 3.0;
+
+            (volume, ix + iy)
+        }
+
+        #[cfg(feature = "dim3")]
+        {
+            let volume = half_extents.x * half_extents.y * half_extents.z * 8.0;
+            let ix = (half_extents.x * half_extents.x) / 3.0;
+            let iy = (half_extents.y * half_extents.y) / 3.0;
+            let iz = (half_extents.z * half_extents.z) / 3.0;
+
+            (volume, Vector::new(iy + iz, ix + iz, ix + iy))
+        }
+    }
+
+    pub(crate) fn from_cuboid(density: f32, half_extents: Vector<f32>) -> Self {
+        let (vol, unit_i) = Self::cuboid_volume_unit_inertia(half_extents);
+        let mass = vol * density;
+        Self::new(Point::origin(), mass, unit_i * mass)
+    }
+}