Fix rustdoc error in Triangle. (#235)

src/shape/shape.rs

@@ -893,10 +893,13 @@ impl Shape for Triangle {
 
     fn feature_normal_at_point(
         &self,
-        feature: FeatureId,
+        _feature: FeatureId,
         _point: &Point<Real>,
     ) -> Option<Unit<Vector<Real>>> {
-        self.feature_normal(feature)
+        #[cfg(feature = "dim2")]
+        return None;
+        #[cfg(feature = "dim3")]
+        return self.feature_normal(_feature);
     }
 }
 

src/shape/triangle.rs

@@ -1,16 +1,17 @@
 //! Definition of the triangle shape.
 
 use crate::math::{Isometry, Point, Real, Vector};
-use crate::shape::{FeatureId, SupportMap};
+use crate::shape::SupportMap;
 use crate::shape::{PolygonalFeature, Segment};
 use crate::utils;
 
 use na::{self, ComplexField, Unit};
 use num::Zero;
-#[cfg(feature = "dim3")]
-use std::f64;
 use std::mem;
 
+#[cfg(feature = "dim3")]
+use {crate::shape::FeatureId, std::f64};
+
 #[cfg(feature = "dim2")]
 use crate::shape::PackedFeatureId;
 
@@ -138,6 +139,7 @@ impl Triangle {
     /// The normal points such that it is collinear to `AB × AC` (where `×` denotes the cross
     /// product).
     #[inline]
+    #[cfg(feature = "dim3")]
     pub fn normal(&self) -> Option<Unit<Vector<Real>>> {
         Unit::try_new(self.scaled_normal(), crate::math::DEFAULT_EPSILON)
     }
@@ -230,10 +232,12 @@ impl Triangle {
     ///
     /// The vector points such that it is collinear to `AB × AC` (where `×` denotes the cross
     /// product).
+    ///
     /// Note that on thin triangles the calculated normals can suffer from numerical issues.
     /// For a more robust (but more computationally expensive) normal calculation, see
     /// [`Triangle::robust_scaled_normal`].
     #[inline]
+    #[cfg(feature = "dim3")]
     pub fn scaled_normal(&self) -> Vector<Real> {
         let ab = self.b - self.a;
         let ac = self.c - self.a;
@@ -535,6 +539,7 @@ impl Triangle {
     }
 
     /// The normal of the given feature of this shape.
+    #[cfg(feature = "dim3")]
     pub fn feature_normal(&self, _: FeatureId) -> Option<Unit<Vector<Real>>> {
         self.normal()
     }