From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 21 Sep 2013 17:10:19 +0000 (+0300)
Subject: Render eye view with off-center projection to better match visible area
X-Git-Url: http://git.tdb.fi/?p=libs%2Fvr.git;a=commitdiff_plain;h=268da92f49360feaf9445ed2b8264d9310d3cebe;hp=aabeac6c43b24adadd6f591bd1607adbfab6c28f

Render eye view with off-center projection to better match visible area
---

diff --git a/source/oculusriftcombiner.cpp b/source/oculusriftcombiner.cpp
index b15c86b..3ebbcc8 100644
--- a/source/oculusriftcombiner.cpp
+++ b/source/oculusriftcombiner.cpp
@@ -22,6 +22,7 @@ const char fs_source[] =
 	"uniform sampler2D texture;\n"
 	"uniform vec4 distortion;\n"
 	"uniform vec4 chromatic;\n"
+	"uniform vec2 lens_center;\n"
 	"uniform vec2 eye_center;\n"
 	"uniform vec3 scale;\n"
 	"varying vec2 texcoord;\n"
@@ -29,13 +30,13 @@ const char fs_source[] =
 	"{\n"
 	"	float r_sq = dot(texcoord, texcoord);\n"
 	"	float f = dot(distortion, vec4(1.0, r_sq, r_sq*r_sq, r_sq*r_sq*r_sq));\n"
-	"	vec2 dtc = (texcoord*f-eye_center)/(scale.xy*scale.z)+0.5;\n"
+	"	vec2 dtc = (texcoord*f-eye_center)/(scale.xy*scale.z)+lens_center;\n"
 	"	if(dtc.x<0.0 || dtc.y<0.0 || dtc.x>1.0 || dtc.y>1.0)\n"
 	"		gl_FragColor = vec4(0.0);\n"
 	"	else\n"
 	"	{\n"
-	"		vec2 red_dtc = (texcoord*f*(chromatic[0]+chromatic[1]*r_sq)-eye_center)/(scale.xy*scale.z)+0.5;\n"
-	"		vec2 blue_dtc = (texcoord*f*(chromatic[2]+chromatic[3]*r_sq)-eye_center)/(scale.xy*scale.z)+0.5;\n"
+	"		vec2 red_dtc = (texcoord*f*(chromatic[0]+chromatic[1]*r_sq)-eye_center)/(scale.xy*scale.z)+lens_center;\n"
+	"		vec2 blue_dtc = (texcoord*f*(chromatic[2]+chromatic[3]*r_sq)-eye_center)/(scale.xy*scale.z)+lens_center;\n"
 	"		gl_FragColor = vec4(texture2D(texture, red_dtc).r, texture2D(texture, dtc).g, texture2D(texture, blue_dtc).b, 1.0);\n"
 	"	}\n"
 	"}\n";
@@ -155,6 +156,7 @@ void OculusRiftCombiner::update_parameters()
 	right_shdata.uniform("scale", 2.0f, 2.5f, oversize);
 
 	fov = Geometry::atan(oversize*0.625f/view_distance)*2.0f;
+	frustum_skew = lens_separation*2-1;
 }
 
 float OculusRiftCombiner::distort(float r) const
diff --git a/source/stereocombiner.cpp b/source/stereocombiner.cpp
index 54ab3e3..a276c3b 100644
--- a/source/stereocombiner.cpp
+++ b/source/stereocombiner.cpp
@@ -7,7 +7,8 @@ StereoCombiner::StereoCombiner():
 	width_div(1),
 	height_div(1),
 	keep_aspect(false),
-	oversize(1.0f)
+	oversize(1.0f),
+	frustum_skew(0.0f)
 { }
 
 } // namespace VR
diff --git a/source/stereocombiner.h b/source/stereocombiner.h
index f078df7..23d4822 100644
--- a/source/stereocombiner.h
+++ b/source/stereocombiner.h
@@ -15,6 +15,7 @@ protected:
 	bool keep_aspect;
 	Geometry::Angle<float> fov;
 	float oversize;
+	float frustum_skew;
 
 	StereoCombiner();
 public:
@@ -25,6 +26,7 @@ public:
 	bool is_aspect_kept() const { return keep_aspect; }
 	const Geometry::Angle<float> &get_field_of_view() const { return fov; }
 	float get_oversize() const { return oversize; }
+	float get_frustum_skew() const { return frustum_skew; }
 
 	virtual void render(const GL::Texture2D &, const GL::Texture2D &) const = 0;
 };
diff --git a/source/stereoview.cpp b/source/stereoview.cpp
index c528023..08949e6 100644
--- a/source/stereoview.cpp
+++ b/source/stereoview.cpp
@@ -49,8 +49,10 @@ void StereoView::setup_frame() const
 	params.near_clip = base_camera.get_near_clip();
 	params.far_clip = base_camera.get_far_clip();
 
-	left.setup_frame(base_camera, offset_axis*-eye_spacing, params);
-	right.setup_frame(base_camera, offset_axis*eye_spacing, params);
+	float frustum_skew = combiner->get_frustum_skew();
+
+	left.setup_frame(base_camera, offset_axis*-eye_spacing, frustum_skew, params);
+	right.setup_frame(base_camera, offset_axis*eye_spacing, -frustum_skew, params);
 
 	renderable.setup_frame();
 }
@@ -98,7 +100,7 @@ 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, const EyeParams &params) const
+void StereoView::Eye::setup_frame(const GL::Camera &base_camera, const GL::Vector3 &offset, float frustum_skew, const EyeParams &params) const
 {
 	camera.set_position(base_camera.get_position()+offset);
 	camera.set_up_direction(base_camera.get_up_direction());
@@ -107,6 +109,7 @@ void StereoView::Eye::setup_frame(const GL::Camera &base_camera, const GL::Vecto
 	camera.set_field_of_view(params.fov);
 	camera.set_aspect(params.aspect);
 	camera.set_depth_clip(params.near_clip, params.far_clip);
+	camera.set_frustum_axis(frustum_skew, 0);
 }
 
 void StereoView::Eye::render(const GL::Renderable &renderable, const GL::Tag &tag) const
diff --git a/source/stereoview.h b/source/stereoview.h
index fe3d6d6..5516823 100644
--- a/source/stereoview.h
+++ b/source/stereoview.h
@@ -41,7 +41,7 @@ private:
 		Eye();
 
 		void create_target(unsigned, unsigned);
-		void setup_frame(const GL::Camera &, const GL::Vector3 &, const EyeParams &) const;
+		void setup_frame(const GL::Camera &, const GL::Vector3 &, float, const EyeParams &) const;
 		void render(const GL::Renderable &, const GL::Tag &) const;
 	};