Improved Plane, fixed Frustum computation from Matrix4, implemented Frustum contains() tests.

src/frustum.rs

@@ -16,14 +16,15 @@
 //! View frustum for visibility determination
 
 use array::Array2;
+use bound::*;
 use matrix::Matrix4;
 use num::BaseFloat;
 use plane::Plane;
 use point::Point3;
 use vector::{Vector, EuclideanVector};
 
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
-pub struct Frustum<S> {
+#[derive(Copy, Clone, Debug, PartialEq, RustcEncodable, RustcDecodable)]
+pub struct Frustum<S: BaseFloat> {
     pub left:   Plane<S>,
     pub right:  Plane<S>,
     pub bottom: Plane<S>,
@@ -34,7 +35,7 @@ pub struct Frustum<S> {
 
 impl<S: BaseFloat + 'static>
 Frustum<S> {
-    /// Constructs a frustum
+    /// Construct a frustum.
     pub fn new(left:   Plane<S>, right:  Plane<S>,
                bottom: Plane<S>, top:    Plane<S>,
                near:   Plane<S>, far:    Plane<S>) -> Frustum<S> {
@@ -48,14 +49,38 @@ Frustum<S> {
         }
     }
 
-    /// Extracts frustum planes from a projection matrix
-    pub fn from_matrix4(mat: Matrix4<S>) -> Frustum<S> {
-        Frustum::new(Plane::from_vector4(mat.row(3).add_v(&mat.row(0)).normalize()),
-                     Plane::from_vector4(mat.row(3).sub_v(&mat.row(0)).normalize()),
-                     Plane::from_vector4(mat.row(3).add_v(&mat.row(1)).normalize()),
-                     Plane::from_vector4(mat.row(3).sub_v(&mat.row(1)).normalize()),
-                     Plane::from_vector4(mat.row(3).add_v(&mat.row(2)).normalize()),
-                     Plane::from_vector4(mat.row(3).sub_v(&mat.row(2)).normalize()))
+    /// Extract frustum planes from a projection matrix.
+    pub fn from_matrix4(mat: Matrix4<S>) -> Option<Frustum<S>> {
+        Some(Frustum::new(
+            match Plane::from_vector4_alt(mat.row(3).add_v(&mat.row(0))).normalize()
+                { Some(p) => p, None => return None },
+            match Plane::from_vector4_alt(mat.row(3).sub_v(&mat.row(0))).normalize()
+                { Some(p) => p, None => return None },
+            match Plane::from_vector4_alt(mat.row(3).add_v(&mat.row(1))).normalize()
+                { Some(p) => p, None => return None },
+            match Plane::from_vector4_alt(mat.row(3).sub_v(&mat.row(1))).normalize()
+                { Some(p) => p, None => return None },
+            match Plane::from_vector4_alt(mat.row(3).add_v(&mat.row(2))).normalize()
+                { Some(p) => p, None => return None },
+            match Plane::from_vector4_alt(mat.row(3).sub_v(&mat.row(2))).normalize()
+                { Some(p) => p, None => return None }
+        ))
+    }
+
+    /// Find the spatial relation of a bound inside this frustum.
+    pub fn contains<B: Bound<S>>(&self, bound: &B) -> Relation {
+        [&self.left, &self.right, &self.top, &self.bottom, &self.near, &self.far]
+            .iter().fold(Relation::In, |cur, p| {
+            let r = bound.relate(p);
+            // if we see Cross, then the result is Cross
+            // if we see In, then we keep the old result
+            // otherwise, take the current result
+            if cur == Relation::Cross || r == Relation::In {
+                cur
+            }else {
+                r
+            }
+        })
     }
 }
 

src/plane.rs

@@ -17,7 +17,7 @@ use std::fmt;
 
 use approx::ApproxEq;
 use intersect::Intersect;
-use num::{BaseFloat, Zero, zero};
+use num::{BaseFloat, one, Zero, zero};
 use point::{Point, Point3};
 use ray::Ray3;
 use vector::{Vector3, Vector4};
@@ -65,9 +65,13 @@ impl<S: BaseFloat> Plane<S> {
 
     /// Construct a plane from the components of a four-dimensional vector
     pub fn from_vector4(v: Vector4<S>) -> Plane<S> {
-        match v {
-            Vector4 { x, y, z, w } => Plane { n: Vector3::new(x, y, z), d: w },
-        }
+        Plane { n: Vector3::new(v.x, v.y, v.z), d: v.w }
+    }
+
+    /// Construct a plane from the components of a four-dimensional vector
+    /// Assuming alternative representation: `A*x + B*y + C*z + D = 0`
+    pub fn from_vector4_alt(v: Vector4<S>) -> Plane<S> {
+        Plane { n: Vector3::new(v.x, v.y, v.z), d: -v.w }
     }
 
     /// Constructs a plane that passes through the the three points `a`, `b` and `c`
@@ -94,6 +98,15 @@ impl<S: BaseFloat> Plane<S> {
     pub fn from_point_normal(p: Point3<S>, n: Vector3<S>) -> Plane<S> {
         Plane { n: n, d: p.dot(&n) }
     }
+
+    /// Normalize a plane.
+    pub fn normalize(&self) -> Option<Plane<S>> {
+        if self.n.approx_eq(&zero()) { None }
+        else {
+            let denom = one::<S>() / self.n.length();
+            Some(Plane::new(self.n.mul_s(denom), self.d*denom))
+        }
+    }
 }
 
 impl<S: BaseFloat> Intersect<Option<Point3<S>>> for (Plane<S>, Ray3<S>) {

src/projection.rs

@@ -97,7 +97,7 @@ impl<S: BaseFloat, A: Angle<S>> PerspectiveFov<S, A> {
 impl<S: BaseFloat + 'static, A: Angle<S>> Projection<S> for PerspectiveFov<S, A> {
     fn to_frustum(&self) -> Frustum<S> {
         // TODO: Could this be faster?
-        Frustum::from_matrix4(self.to_matrix4())
+        Frustum::from_matrix4(self.to_matrix4()).unwrap()
     }
 }
 
@@ -153,7 +153,7 @@ pub struct Perspective<S> {
 impl<S: BaseFloat + 'static> Projection<S> for Perspective<S> {
     fn to_frustum(&self) -> Frustum<S> {
         // TODO: Could this be faster?
-        Frustum::from_matrix4(self.to_matrix4())
+        Frustum::from_matrix4(self.to_matrix4()).unwrap()
     }
 }
 

tests/frustum.rs

@@ -0,0 +1,40 @@
+// Copyright 2015 The CGMath Developers. For a full listing of the authors,
+// refer to the AUTHORS file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+extern crate cgmath;
+
+use cgmath::{PerspectiveFov, Point3, Projection, Relation, Sphere, rad};
+
+#[test]
+fn test_contains() {
+    let frustum = PerspectiveFov {
+        fovy: rad(1f32),
+        aspect: 1f32,
+        near: 1f32,
+        far: 10f32,
+    }.to_frustum();
+    assert_eq!(frustum.contains(&Sphere {
+            center: Point3::new(0f32, 0f32, -5f32),
+            radius: 1f32,
+        }), Relation::In);
+    assert_eq!(frustum.contains(&Sphere {
+            center: Point3::new(0f32, 3f32, -5f32),
+            radius: 1f32,
+        }), Relation::Cross);
+    assert_eq!(frustum.contains(&Sphere {
+            center: Point3::new(0f32, 0f32, 5f32),
+            radius: 1f32,
+        }), Relation::Out);
+}