From 65bf7af24e2bf0f7e5b7b7f5ceee1b64f0e73387 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Wed, 2 Dec 2015 10:03:25 +1100
Subject: [PATCH] matrix: perspective construction takes a Z-range

---
 matrix.cpp | 6 +++---
 matrix.hpp | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/matrix.cpp b/matrix.cpp
index 5d9b1e62..63167538 100644
--- a/matrix.cpp
+++ b/matrix.cpp
@@ -307,14 +307,14 @@ matrix<S,T>::ortho2D (T left, T right,
 //-----------------------------------------------------------------------------
 template <size_t S, typename T>
 matrix4<T>
-matrix<S,T>::perspective (T fov, T aspect, T near, T far)
+matrix<S,T>::perspective (T fov, T aspect, range<T> Z)
 {
     T f = std::tan (fov / 2);
 
     T tx = 1 / (f * aspect);
     T ty = 1 / f;
-    T z1 =     (far + near) / (near - far);
-    T z2 = (2 * far * near) / (near - far);
+    T z1 =     (Z.max + Z.min) / (Z.min - Z.max);
+    T z2 = (2 * Z.max * Z.min) / (Z.min - Z.max);
 
     return { {
         { tx,  0,  0,  0 },
diff --git a/matrix.hpp b/matrix.hpp
index 81489f27..88076155 100644
--- a/matrix.hpp
+++ b/matrix.hpp
@@ -18,6 +18,7 @@
 #define __UTIL_MATRIX_HPP
 
 #include "point.hpp"
+#include "range.hpp"
 
 #include <iostream>
 
@@ -65,7 +66,7 @@ namespace util {
         // Perspective matrices
         static matrix<4,T> ortho   (T left, T right, T bottom, T top, T near, T far);
         static matrix<4,T> ortho2D (T left, T right, T bottom, T top);
-        static matrix<4,T> perspective (T fov, T aspect, T near, T far);
+        static matrix<4,T> perspective (T fov, T aspect, range<T> Z);
         static matrix<4,T> look_at (point<3,T> eye, point<3,T> centre, vector<3,T> up);
 
         // Affine matrices