From 23a6e642715fab2f275a2015ea079137cb31036d Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 18 Sep 2016 16:56:53 +0300
Subject: [PATCH] Use matrices for eye offsets instead of a simple spacing

---
 source/ovr/oculusriftdevice.cpp |  4 +++-
 source/stereoview.cpp           | 24 +++++++++++++++---------
 source/stereoview.h             |  5 +++--
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/source/ovr/oculusriftdevice.cpp b/source/ovr/oculusriftdevice.cpp
index efc0cfa..38fd20e 100644
--- a/source/ovr/oculusriftdevice.cpp
+++ b/source/ovr/oculusriftdevice.cpp
@@ -59,7 +59,9 @@ void OculusRiftDevice::configure_view(StereoView &view) const
 {
 	ovrEyeRenderDesc left_desc = ovrHmd_GetRenderDesc(priv->ovr_hmd, ovrEye_Left, priv->ovr_hmd->DefaultEyeFov[ovrEye_Left]);
 	ovrEyeRenderDesc right_desc = ovrHmd_GetRenderDesc(priv->ovr_hmd, ovrEye_Right, priv->ovr_hmd->DefaultEyeFov[ovrEye_Left]);
-	view.set_eye_spacing(left_desc.HmdToEyeViewOffset.x-right_desc.HmdToEyeViewOffset.x);
+	const ovrVector3f &l = left_desc.HmdToEyeViewOffset;
+	const ovrVector3f &r = right_desc.HmdToEyeViewOffset;
+	view.set_eye_matrices(GL::Matrix::translation(GL::Vector3(l.x, l.y, l.z)), GL::Matrix::translation(GL::Vector3(r.x, r.y, r.z)));
 }
 
 OculusRiftCamera *OculusRiftDevice::create_camera(const GL::Camera &bc)
diff --git a/source/stereoview.cpp b/source/stereoview.cpp
index 5945016..73be19c 100644
--- a/source/stereoview.cpp
+++ b/source/stereoview.cpp
@@ -44,7 +44,14 @@ void StereoView::set_content(const GL::Renderable *r)
 
 void StereoView::set_eye_spacing(float s)
 {
-	eye_spacing = s;
+	GL::Vector3 offset(s/2, 0, 0);
+	set_eye_matrices(GL::Matrix::translation(-offset), GL::Matrix::translation(offset));
+}
+
+void StereoView::set_eye_matrices(const GL::Matrix &left_matrix, const GL::Matrix &right_matrix)
+{
+	left.offset_matrix = left_matrix;
+	right.offset_matrix = right_matrix;
 }
 
 void StereoView::set_strabismus(const Geometry::Angle<float> &s)
@@ -57,8 +64,6 @@ void StereoView::setup_frame() const
 	if(head_camera)
 		head_camera->update();
 
-	GL::Vector3 offset_axis = normalize(cross(base_camera.get_look_direction(), base_camera.get_up_direction()))*0.5f;
-
 	EyeParams params;
 	params.fov = combiner.get_field_of_view();
 	if(params.fov==Geometry::Angle<float>::zero())
@@ -72,8 +77,8 @@ void StereoView::setup_frame() const
 	float halfw = tan(params.fov/2.0f)*params.aspect;
 	frustum_skew = tan(Geometry::atan<float>(frustum_skew*halfw)+strabismus)/halfw;
 
-	left.setup_frame(base_camera, offset_axis*-eye_spacing, frustum_skew, params);
-	right.setup_frame(base_camera, offset_axis*eye_spacing, -frustum_skew, params);
+	left.setup_frame(base_camera, frustum_skew, params);
+	right.setup_frame(base_camera, -frustum_skew, params);
 }
 
 void StereoView::render() const
@@ -113,11 +118,12 @@ void StereoView::Eye::create_target(unsigned w, unsigned h)
 	target = new RenderTarget(w, h);
 }
 
-void StereoView::Eye::setup_frame(const GL::Camera &base_camera, const GL::Vector3 &offset, float frustum_skew, const EyeParams &params) const
+void StereoView::Eye::setup_frame(const GL::Camera &base_camera, float frustum_skew, const EyeParams &params) const
 {
-	camera.set_position(base_camera.get_position()+offset);
-	camera.set_up_direction(base_camera.get_up_direction());
-	camera.set_look_direction(base_camera.get_look_direction());
+	GL::Matrix matrix = base_camera.get_object_matrix()*offset_matrix;
+	camera.set_position(matrix*GL::Vector3());
+	camera.set_up_direction((matrix*GL::Vector4(0, 1, 0, 0)).slice<3>(0));
+	camera.set_look_direction((matrix*GL::Vector4(0, 0, -1, 0)).slice<3>(0));
 
 	camera.set_field_of_view(params.fov);
 	camera.set_aspect(params.aspect);
diff --git a/source/stereoview.h b/source/stereoview.h
index ff34706..bc9073e 100644
--- a/source/stereoview.h
+++ b/source/stereoview.h
@@ -37,12 +37,13 @@ private:
 	struct Eye
 	{
 		mutable GL::Camera camera;
+		GL::Matrix offset_matrix;
 		RenderTarget *target;
 
 		Eye();
 
 		void create_target(unsigned, unsigned);
-		void setup_frame(const GL::Camera &, const GL::Vector3 &, float, const EyeParams &) const;
+		void setup_frame(const GL::Camera &, float, const EyeParams &) const;
 		void render(const GL::Renderable &) const;
 	};
 
@@ -52,7 +53,6 @@ private:
 	const GL::Renderable *content;
 	Eye left;
 	Eye right;
-	float eye_spacing;
 	Geometry::Angle<float> strabismus;
 
 public:
@@ -64,6 +64,7 @@ private:
 public:
 	void set_content(const GL::Renderable *);
 	void set_eye_spacing(float);
+	void set_eye_matrices(const GL::Matrix &, const GL::Matrix &);
 	void set_strabismus(const Geometry::Angle<float> &);
 
 private:
-- 
2.43.0