From 8100f49047d003740aa183eaa60376e060e12b4d Mon Sep 17 00:00:00 2001
From: Philippe Renon <philippe_renon@yahoo.fr>
Date: Mon, 26 Oct 2020 12:26:24 +0100
Subject: [PATCH] fix OpenGL (is actually RhNo and not LhNo)

add LhZo and RhNo
---
 src/geometry/ndc.rs         |  16 +++++-
 src/geometry/perspective.rs | 101 ++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+), 2 deletions(-)

diff --git a/src/geometry/ndc.rs b/src/geometry/ndc.rs
index 4c489018..31a76f4f 100644
--- a/src/geometry/ndc.rs
+++ b/src/geometry/ndc.rs
@@ -7,6 +7,18 @@ pub struct LhNo {}
 
 impl System for LhNo {}
 
+/// Left handed with a depth range of 0 to 1.
+#[derive(Default)]
+pub struct LhZo {}
+
+impl System for LhZo {}
+
+/// Right handed with a depth range of -1 to 1.
+#[derive(Default)]
+pub struct RhNo {}
+
+impl System for RhNo {}
+
 /// Right handed with a depth range of 0 to 1.
 #[derive(Default)]
 pub struct RhZo {}
@@ -15,8 +27,8 @@ impl System for RhZo {}
 
 // Aliases for commonly used NDCs.
 
-/// OpenGL NDC (left handed with a depth range of -1 to 1).
-pub type OpenGL = LhNo;
+/// OpenGL NDC (right handed with a depth range of -1 to 1).
+pub type OpenGL = RhNo;
 
 /// Vulkan NDC (right handed with a depth range of 0 to 1).
 pub type Vulkan = RhZo;
diff --git a/src/geometry/perspective.rs b/src/geometry/perspective.rs
index 1e065290..87bc655e 100644
--- a/src/geometry/perspective.rs
+++ b/src/geometry/perspective.rs
@@ -293,6 +293,107 @@ impl<N: RealField> Perspective3<LhNo, N> {
     }
 }
 
+/// LhZo specialization (Left handed with a depth range of 0 to 1).
+impl<N: RealField> Perspective3<LhZo, N> {
+    /// Implementation note: new() must be specialized because it calls other specialized functions.
+    pub fn new(aspect: N, fovy: N, znear: N, zfar: N) -> Self {
+        assert!(
+            !relative_eq!(zfar - znear, N::zero()),
+            "The near-plane and far-plane must not be superimposed."
+        );
+        assert!(
+            !relative_eq!(aspect, N::zero()),
+            "The aspect ratio must not be zero."
+        );
+
+        let matrix = Matrix4::identity();
+        let mut res = Self::from_matrix_unchecked(matrix);
+
+        res.set_fovy(fovy);
+        res.set_aspect(aspect);
+        res.set_znear_and_zfar(znear, zfar);
+
+        res.matrix[(3, 3)] = N::zero();
+        res.matrix[(3, 2)] = N::one();
+
+        res
+    }
+
+    /// Updates this perspective matrix with a new near plane offset of the view frustum.
+    /// Implementation note: set_znear() must be specialized because it calls other specialized functions.
+    #[inline]
+    pub fn set_znear(&mut self, znear: N) {
+        let zfar = self.zfar();
+        self.set_znear_and_zfar(znear, zfar);
+    }
+
+    /// Updates this perspective matrix with a new far plane offset of the view frustum.
+    /// Implementation note: set_zfar() must be specialized because it calls other specialized functions.
+    #[inline]
+    pub fn set_zfar(&mut self, zfar: N) {
+        let znear = self.znear();
+        self.set_znear_and_zfar(znear, zfar);
+    }
+
+    /// Updates this perspective matrix with new near and far plane offsets of the view frustum.
+    #[inline]
+    pub fn set_znear_and_zfar(&mut self, znear: N, zfar: N) {
+        self.matrix[(2, 2)] = zfar / (zfar - znear);
+        self.matrix[(2, 3)] = -(zfar * znear) / (zfar - znear);
+    }
+}
+
+// RhNo specialization (right handed with a depth range of -1 to 1).
+impl<N: RealField> Perspective3<RhNo, N> {
+    /// Implementation note: new() must be specialized because it calls other specialized functions.
+    pub fn new(aspect: N, fovy: N, znear: N, zfar: N) -> Self {
+        assert!(
+            !relative_eq!(zfar - znear, N::zero()),
+            "The near-plane and far-plane must not be superimposed."
+        );
+        assert!(
+            !relative_eq!(aspect, N::zero()),
+            "The aspect ratio must not be zero."
+        );
+
+        let matrix = Matrix4::identity();
+        let mut res = Self::from_matrix_unchecked(matrix);
+
+        res.set_fovy(fovy);
+        res.set_aspect(aspect);
+        res.set_znear_and_zfar(znear, zfar);
+
+        res.matrix[(3, 3)] = N::zero();
+        res.matrix[(3, 2)] = -N::one();
+
+        res
+    }
+
+    /// Updates this perspective matrix with a new near plane offset of the view frustum.
+    /// Implementation note: set_znear() must be specialized because it calls other specialized functions.
+    #[inline]
+    pub fn set_znear(&mut self, znear: N) {
+        let zfar = self.zfar();
+        self.set_znear_and_zfar(znear, zfar);
+    }
+
+    /// Updates this perspective matrix with a new far plane offset of the view frustum.
+    /// Implementation note: set_zfar() must be specialized because it calls other specialized functions.
+    #[inline]
+    pub fn set_zfar(&mut self, zfar: N) {
+        let znear = self.znear();
+        self.set_znear_and_zfar(znear, zfar);
+    }
+
+    /// Updates this perspective matrix with new near and far plane offsets of the view frustum.
+    #[inline]
+    pub fn set_znear_and_zfar(&mut self, znear: N, zfar: N) {
+        let two: N = crate::convert(2.0);
+        self.matrix[(2, 2)] = -(zfar + znear) / (zfar - znear);
+        self.matrix[(2, 3)] = -(two * zfar * znear) / (zfar - znear);
+    }
+}
+
 // RhZo specialization (right handed with a depth range of 0 to 1).
 impl<N: RealField> Perspective3<RhZo, N> {
     /// Implementation note: new() must be specialized because it calls other specialized functions.