Add projection module

src/cgmath/lib.rs

@@ -27,3 +27,5 @@ pub mod matrix;
 pub mod point;
 pub mod quaternion;
 pub mod vector;
+
+pub mod projection;

src/cgmath/projection.rs

@@ -0,0 +1,99 @@
+// Copyright 2013 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.
+
+use std::num::{zero, one};
+
+use matrix::Mat4;
+
+/// Ick. We really need better from-int support in std::num.
+#[inline]
+fn two<T: Num>() -> T {
+    one::<T>() + one::<T>()
+}
+
+/// Create a perspective projection matrix
+///
+/// Note: the fovy parameter should be specified in degrees.
+///
+/// This is the equivalent of the gluPerspective function, the algorithm of which
+/// can be found [here](http://www.opengl.org/wiki/GluPerspective_code).
+pub fn perspective<S: Clone + Float>(fovy: S, aspectRatio: S, near: S, far: S) -> Mat4<S> {
+    let ymax = near * (fovy / two::<S>()).to_radians().tan();
+    let xmax = ymax * aspectRatio;
+
+    frustum(-xmax, xmax, -ymax, ymax, near, far)
+}
+
+/// Define a view frustrum
+///
+/// This is the equivalent of the now deprecated [glFrustrum]
+/// (http://www.opengl.org/sdk/docs/man2/xhtml/glFrustum.xml) function.
+pub fn frustum<S: Clone + Float>(left: S, right: S, bottom: S, top: S, near: S, far: S) -> Mat4<S> {
+    let c0r0 = (two::<S>() * near) / (right - left);
+    let c0r1 = zero();
+    let c0r2 = zero();
+    let c0r3 = zero();
+
+    let c1r0 = zero();
+    let c1r1 = (two::<S>() * near) / (top - bottom);
+    let c1r2 = zero();
+    let c1r3 = zero();
+
+    let c2r0 = (right + left) / (right - left);
+    let c2r1 = (top + bottom) / (top - bottom);
+    let c2r2 = -(far + near) / (far - near);
+    let c2r3 = -one::<S>();
+
+    let c3r0 = zero();
+    let c3r1 = zero();
+    let c3r2 = -(two::<S>() * far * near) / (far - near);
+    let c3r3 = zero();
+
+    Mat4::new(c0r0, c0r1, c0r2, c0r3,
+              c1r0, c1r1, c1r2, c1r3,
+              c2r0, c2r1, c2r2, c2r3,
+              c3r0, c3r1, c3r2, c3r3)
+}
+
+/// Create an orthographic projection matrix
+///
+/// This is the equivalent of the now deprecated [glOrtho]
+/// (http://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml) function.
+pub fn ortho<S: Clone + Float>(left: S, right: S, bottom: S, top: S, near: S, far: S) -> Mat4<S> {
+    let c0r0 = two::<S>() / (right - left);
+    let c0r1 = zero();
+    let c0r2 = zero();
+    let c0r3 = zero();
+
+    let c1r0 = zero();
+    let c1r1 = two::<S>() / (top - bottom);
+    let c1r2 = zero();
+    let c1r3 = zero();
+
+    let c2r0 = zero();
+    let c2r1 = zero();
+    let c2r2 = -two::<S>() / (far - near);
+    let c2r3 = zero();
+
+    let c3r0 = -(right + left) / (right - left);
+    let c3r1 = -(top + bottom) / (top - bottom);
+    let c3r2 = -(far + near) / (far - near);
+    let c3r3 = one();
+
+    Mat4::new(c0r0, c0r1, c0r2, c0r3,
+              c1r0, c1r1, c1r2, c1r3,
+              c2r0, c2r1, c2r2, c2r3,
+              c3r0, c3r1, c3r2, c3r3)
+}