From 0b9fa4d7eb2acb22f5f4f31bbd508d0216421108 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 3 Oct 2016 16:05:34 +0300
Subject: [PATCH] Add functions to use absolute tracking

A.k.a. room scale
---
 source/headtrackingcamera.cpp  | 10 ++++++++--
 source/headtrackingcamera.h    |  2 ++
 source/libovr/libovrsystem.cpp |  6 ++++++
 source/libovr/libovrsystem.h   |  1 +
 source/openvr/openvrsystem.cpp |  5 +++++
 source/openvr/openvrsystem.h   |  1 +
 source/system.h                |  1 +
 7 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/source/headtrackingcamera.cpp b/source/headtrackingcamera.cpp
index 95868e2..42eedd5 100644
--- a/source/headtrackingcamera.cpp
+++ b/source/headtrackingcamera.cpp
@@ -4,14 +4,20 @@ namespace Msp {
 namespace VR {
 
 HeadTrackingCamera::HeadTrackingCamera(const GL::Camera &c):
-	base_camera(c)
+	base_camera(c),
+	elevation_offset(0)
 { }
 
+void HeadTrackingCamera::set_elevation_offset(float o)
+{
+	elevation_offset = o;
+}
+
 void HeadTrackingCamera::update_from_matrix(const GL::Matrix &hmd_matrix)
 {
 	GL::Matrix matrix = base_camera.get_object_matrix()*hmd_matrix;
 
-	set_position(matrix*GL::Vector3());
+	set_position(matrix*GL::Vector3()+base_camera.get_up_direction()*elevation_offset);
 	set_look_direction((matrix*GL::Vector4(0, 0, -1, 0)).slice<3>(0));
 	set_up_direction((matrix*GL::Vector4(0, 1, 0, 0)).slice<3>(0));
 
diff --git a/source/headtrackingcamera.h b/source/headtrackingcamera.h
index 5bb911e..c200136 100644
--- a/source/headtrackingcamera.h
+++ b/source/headtrackingcamera.h
@@ -10,11 +10,13 @@ class HeadTrackingCamera: public Msp::GL::Camera
 {
 protected:
 	const GL::Camera &base_camera;
+	float elevation_offset;
 
 	HeadTrackingCamera(const GL::Camera &);
 public:
 	virtual ~HeadTrackingCamera() { }
 
+	void set_elevation_offset(float);
 	virtual void reset_tracking() { }
 	virtual void update() = 0;
 protected:
diff --git a/source/libovr/libovrsystem.cpp b/source/libovr/libovrsystem.cpp
index c8183b0..0136d49 100644
--- a/source/libovr/libovrsystem.cpp
+++ b/source/libovr/libovrsystem.cpp
@@ -65,6 +65,12 @@ void LibOVRSystem::configure_view(StereoView &view) const
 	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)));
 }
 
+void LibOVRSystem::set_absolute_tracking(bool a)
+{
+	if(a)
+		throw invalid_argument("absolute tracking not supported");
+}
+
 LibOVRCamera *LibOVRSystem::create_camera(const GL::Camera &bc)
 {
 	return new LibOVRCamera(*this, bc);
diff --git a/source/libovr/libovrsystem.h b/source/libovr/libovrsystem.h
index d5623a0..a7978e4 100644
--- a/source/libovr/libovrsystem.h
+++ b/source/libovr/libovrsystem.h
@@ -28,6 +28,7 @@ public:
 
 	virtual void configure_window(Graphics::Window &) const;
 	virtual void configure_view(StereoView &) const;
+	virtual void set_absolute_tracking(bool);
 	virtual LibOVRCamera *create_camera(const GL::Camera &);
 	virtual LibOVRCombiner *create_combiner(GL::View &);
 
diff --git a/source/openvr/openvrsystem.cpp b/source/openvr/openvrsystem.cpp
index ec6b418..e71ba33 100644
--- a/source/openvr/openvrsystem.cpp
+++ b/source/openvr/openvrsystem.cpp
@@ -69,6 +69,11 @@ void OpenVRSystem::configure_view(StereoView &view) const
 	view.set_eye_matrices(convert_matrix(left), convert_matrix(right));
 }
 
+void OpenVRSystem::set_absolute_tracking(bool a)
+{
+	vr::VRCompositor()->SetTrackingSpace(a ? vr::TrackingUniverseStanding : vr::TrackingUniverseSeated);
+}
+
 OpenVRCamera *OpenVRSystem::create_camera(const GL::Camera &bc)
 {
 	return new OpenVRCamera(*this, bc);
diff --git a/source/openvr/openvrsystem.h b/source/openvr/openvrsystem.h
index 98ad556..3e401ed 100644
--- a/source/openvr/openvrsystem.h
+++ b/source/openvr/openvrsystem.h
@@ -22,6 +22,7 @@ public:
 
 	virtual void configure_window(Graphics::Window &) const { }
 	virtual void configure_view(StereoView &) const;
+	virtual void set_absolute_tracking(bool);
 	virtual OpenVRCamera *create_camera(const GL::Camera &);
 	virtual OpenVRCombiner *create_combiner(GL::View &);
 
diff --git a/source/system.h b/source/system.h
index 0610e29..46c65d9 100644
--- a/source/system.h
+++ b/source/system.h
@@ -23,6 +23,7 @@ public:
 
 	virtual void configure_window(Graphics::Window &) const = 0;
 	virtual void configure_view(StereoView &) const = 0;
+	virtual void set_absolute_tracking(bool) = 0;
 	virtual HeadTrackingCamera *create_camera(const GL::Camera &) = 0;
 	virtual StereoCombiner *create_combiner(GL::View &) = 0;
 };
-- 
2.43.0