reintroduce generic mobile vr interface

8 files changed, 825 insertions, 0 deletions

diff --git a/modules/mobile_vr/SCsub b/modules/mobile_vr/SCsub
new file mode 100644
index 0000000000..b4e2edcca1
--- /dev/null
+++ b/modules/mobile_vr/SCsub
@@ -0,0 +1,13 @@
+#!/usr/bin/env python
+
+import os
+import methods
+
+Import('env')
+Import('env_modules')
+
+env_mobile_vr = env_modules.Clone()
+
+env_mobile_vr.add_source_files(env.modules_sources, '*.cpp')
+
+SConscript("shaders/SCsub")
diff --git a/modules/mobile_vr/config.py b/modules/mobile_vr/config.py
new file mode 100644
index 0000000000..d0156b1b77
--- /dev/null
+++ b/modules/mobile_vr/config.py
@@ -0,0 +1,6 @@
+def can_build(platform):
+	# should probably change this to only be true on iOS and Android
+	return True
+
+def configure(env):
+	pass
\ No newline at end of file
diff --git a/modules/mobile_vr/mobile_interface.cpp b/modules/mobile_vr/mobile_interface.cpp
new file mode 100644
index 0000000000..f5c9bccaba
--- /dev/null
+++ b/modules/mobile_vr/mobile_interface.cpp
@@ -0,0 +1,511 @@
+/*************************************************************************/
+/*  mobile_interface.cpp                                                 */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                    http://www.godotengine.org                         */
+/*************************************************************************/
+/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "mobile_interface.h"
+#include "core/os/input.h"
+#include "core/os/os.h"
+#include "servers/visual/visual_server_global.h"
+
+StringName MobileVRInterface::get_name() const {
+	return "Native mobile";
+};
+
+Vector3 MobileVRInterface::scale_magneto(const Vector3 &p_magnetometer) {
+	// Our magnetometer doesn't give us nice clean data.
+	// Well it may on Mac OS X because we're getting a calibrated value in the current implementation but Android we're getting raw data.
+	// This is a fairly simple adjustment we can do to correct for the magnetometer data being elliptical
+
+	Vector3 mag_raw = p_magnetometer;
+	Vector3 mag_scaled = p_magnetometer;
+
+	// update our variables every x frames
+	if (mag_count > 20) {
+		mag_current_min = mag_next_min;
+		mag_current_max = mag_next_max;
+		mag_count = 0;
+	} else {
+		mag_count++;
+	};
+
+	// adjust our min and max
+	if (mag_raw.x > mag_next_max.x) mag_next_max.x = mag_raw.x;
+	if (mag_raw.y > mag_next_max.y) mag_next_max.y = mag_raw.y;
+	if (mag_raw.z > mag_next_max.z) mag_next_max.z = mag_raw.z;
+
+	if (mag_raw.x < mag_next_min.x) mag_next_min.x = mag_raw.x;
+	if (mag_raw.y < mag_next_min.y) mag_next_min.y = mag_raw.y;
+	if (mag_raw.z < mag_next_min.z) mag_next_min.z = mag_raw.z;
+
+	// scale our x, y and z
+	if (!(mag_current_max.x - mag_current_min.x)) {
+		mag_raw.x -= (mag_current_min.x + mag_current_max.x) / 2.0;
+		mag_scaled.x = (mag_raw.x - mag_current_min.x) / ((mag_current_max.x - mag_current_min.x) * 2.0 - 1.0);
+	};
+
+	if (!(mag_current_max.y - mag_current_min.y)) {
+		mag_raw.y -= (mag_current_min.y + mag_current_max.y) / 2.0;
+		mag_scaled.y = (mag_raw.y - mag_current_min.y) / ((mag_current_max.y - mag_current_min.y) * 2.0 - 1.0);
+	};
+
+	if (!(mag_current_max.z - mag_current_min.z)) {
+		mag_raw.z -= (mag_current_min.z + mag_current_max.z) / 2.0;
+		mag_scaled.z = (mag_raw.z - mag_current_min.z) / ((mag_current_max.z - mag_current_min.z) * 2.0 - 1.0);
+	};
+
+	return mag_scaled;
+};
+
+Basis MobileVRInterface::combine_acc_mag(const Vector3 &p_grav, const Vector3 &p_magneto) {
+	// yup, stock standard cross product solution...
+	Vector3 up = -p_grav.normalized();
+
+	Vector3 magneto_east = up.cross(p_magneto.normalized()); // or is this west?, but should be horizon aligned now
+	magneto_east.normalize();
+
+	Vector3 magneto = up.cross(magneto_east); // and now we have a horizon aligned north
+	magneto.normalize();
+
+	// We use our gravity and magnetometer vectors to construct our matrix
+	Basis acc_mag_m3;
+	acc_mag_m3.elements[0] = -magneto_east;
+	acc_mag_m3.elements[1] = up;
+	acc_mag_m3.elements[2] = magneto;
+
+	return acc_mag_m3;
+};
+
+void MobileVRInterface::set_position_from_sensors() {
+	_THREAD_SAFE_METHOD_
+
+	// this is a helper function that attempts to adjust our transform using our 9dof sensors
+	// 9dof is a misleading marketing term coming from 3 accelerometer axis + 3 gyro axis + 3 magnetometer axis = 9 axis
+	// but in reality this only offers 3 dof (yaw, pitch, roll) orientation
+
+	uint64_t ticks = OS::get_singleton()->get_ticks_usec();
+	uint64_t ticks_elapsed = ticks - last_ticks;
+	float delta_time = (double)ticks_elapsed / 1000000.0;
+
+	// few things we need
+	Input *input = Input::get_singleton();
+	Vector3 down(0.0, -1.0, 0.0); // Down is Y negative
+	Vector3 north(0.0, 0.0, 1.0); // North is Z positive
+
+	// make copies of our inputs
+	Vector3 acc = input->get_accelerometer();
+	Vector3 gyro = input->get_gyroscope();
+	Vector3 grav = input->get_gravity();
+	Vector3 magneto = scale_magneto(input->get_magnetometer()); // this may be overkill on iOS because we're already getting a calibrated magnetometer reading
+
+	if (sensor_first) {
+		sensor_first = false;
+	} else {
+		acc = scrub(acc, last_accerometer_data, 2, 0.2);
+		magneto = scrub(magneto, last_magnetometer_data, 3, 0.3);
+	};
+
+	last_accerometer_data = acc;
+	last_magnetometer_data = magneto;
+
+	if (grav.length() < 0.1) {
+		// not ideal but use our accelerometer, this will contain shakey shakey user behaviour
+		// maybe look into some math but I'm guessing that if this isn't available, its because we lack the gyro sensor to actually work out
+		// what a stable gravity vector is
+		grav = acc;
+		if (grav.length() > 0.1) {
+			has_gyro = true;
+		};
+	} else {
+		has_gyro = true;
+	};
+
+	bool has_magneto = magneto.length() > 0.1;
+	bool has_grav = grav.length() > 0.1;
+
+#ifdef ANDROID_ENABLED
+	///@TODO needs testing, i don't have a gyro, potentially can be removed depending on what comes out of issue #8101
+	// On Android x and z axis seem inverted
+	gyro.x = -gyro.x;
+	gyro.z = -gyro.z;
+	grav.x = -grav.x;
+	grav.z = -grav.z;
+	magneto.x = -magneto.x;
+	magneto.z = -magneto.z;
+#endif
+
+	if (has_gyro) {
+		// start with applying our gyro (do NOT smooth our gyro!)
+		Basis rotate;
+		rotate.rotate(orientation.get_axis(0), gyro.x * delta_time);
+		rotate.rotate(orientation.get_axis(1), gyro.y * delta_time);
+		rotate.rotate(orientation.get_axis(2), gyro.z * delta_time);
+		orientation = rotate * orientation;
+	};
+
+	///@TODO improve this, the magnetometer is very fidgity sometimes flipping the axis for no apparent reason (probably a bug on my part)
+	// if you have a gyro + accelerometer that combo tends to be better then combining all three but without a gyro you need the magnetometer..
+	if (has_magneto && has_grav && !has_gyro) {
+		// convert to quaternions, easier to smooth those out
+		Quat transform_quat(orientation);
+		Quat acc_mag_quat(combine_acc_mag(grav, magneto));
+		transform_quat = transform_quat.slerp(acc_mag_quat, 0.1);
+		orientation = Basis(transform_quat);
+	} else if (has_grav) {
+		// use gravity vector to make sure down is down...
+		// transform gravity into our world space
+		grav.normalize();
+		Vector3 grav_adj = orientation.xform(grav);
+		float dot = grav_adj.dot(down);
+		if ((dot > -1.0) && (dot < 1.0)) {
+			// axis around which we have this rotation
+			Vector3 axis = grav_adj.cross(down);
+			axis.normalize();
+
+			Basis drift_compensation(axis, acos(dot) * delta_time * 10);
+			orientation = drift_compensation * orientation;
+		};
+	};
+
+	// JIC
+	orientation.orthonormalize();
+
+	last_ticks = ticks;
+};
+
+void MobileVRInterface::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("set_iod", "iod"), &MobileVRInterface::set_iod);
+	ClassDB::bind_method(D_METHOD("get_iod"), &MobileVRInterface::get_iod);
+
+	ClassDB::bind_method(D_METHOD("set_display_width", "display_width"), &MobileVRInterface::set_display_width);
+	ClassDB::bind_method(D_METHOD("get_display_width"), &MobileVRInterface::get_display_width);
+
+	ClassDB::bind_method(D_METHOD("set_display_to_lens", "display_to_lens"), &MobileVRInterface::set_display_to_lens);
+	ClassDB::bind_method(D_METHOD("get_display_to_lens"), &MobileVRInterface::get_display_to_lens);
+
+	ClassDB::bind_method(D_METHOD("set_oversample", "oversample"), &MobileVRInterface::set_oversample);
+	ClassDB::bind_method(D_METHOD("get_oversample"), &MobileVRInterface::get_oversample);
+
+	ClassDB::bind_method(D_METHOD("set_k1", "k"), &MobileVRInterface::set_k1);
+	ClassDB::bind_method(D_METHOD("get_k1"), &MobileVRInterface::get_k1);
+
+	ClassDB::bind_method(D_METHOD("set_k2", "k"), &MobileVRInterface::set_k2);
+	ClassDB::bind_method(D_METHOD("get_k2"), &MobileVRInterface::get_k2);
+
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "iod", PROPERTY_HINT_RANGE, "4.0,10.0,0.1"), "set_iod", "get_iod");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "display_width", PROPERTY_HINT_RANGE, "5.0,25.0,0.1"), "set_display_width", "get_display_width");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "display_to_lens", PROPERTY_HINT_RANGE, "5.0,25.0,0.1"), "set_display_to_lens", "get_display_to_lens");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "oversample", PROPERTY_HINT_RANGE, "1.0,2.0,0.1"), "set_oversample", "get_oversample");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "k1", PROPERTY_HINT_RANGE, "0.1,10.0,0.0001"), "set_k1", "get_k1");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "k2", PROPERTY_HINT_RANGE, "0.1,10.0,0.0001"), "set_k2", "get_k2");
+}
+
+void MobileVRInterface::set_iod(const real_t p_iod) {
+	intraocular_dist = p_iod;
+};
+
+real_t MobileVRInterface::get_iod() const {
+	return intraocular_dist;
+};
+
+void MobileVRInterface::set_display_width(const real_t p_display_width) {
+	display_width = p_display_width;
+};
+
+real_t MobileVRInterface::get_display_width() const {
+	return display_width;
+};
+
+void MobileVRInterface::set_display_to_lens(const real_t p_display_to_lens) {
+	display_to_lens = p_display_to_lens;
+};
+
+real_t MobileVRInterface::get_display_to_lens() const {
+	return display_to_lens;
+};
+
+void MobileVRInterface::set_oversample(const real_t p_oversample) {
+	oversample = p_oversample;
+};
+
+real_t MobileVRInterface::get_oversample() const {
+	return oversample;
+};
+
+void MobileVRInterface::set_k1(const real_t p_k1) {
+	k1 = p_k1;
+};
+
+real_t MobileVRInterface::get_k1() const {
+	return k1;
+};
+
+void MobileVRInterface::set_k2(const real_t p_k2) {
+	k2 = p_k2;
+};
+
+real_t MobileVRInterface::get_k2() const {
+	return k2;
+};
+
+bool MobileVRInterface::is_installed() {
+	// we don't have any middle ware here, if we have our interface, we can use it
+	return true;
+};
+
+bool MobileVRInterface::hmd_is_present() {
+	// our device is our HMD
+	return true;
+};
+
+bool MobileVRInterface::supports_hmd() {
+	// our device is our HMD
+	return true;
+};
+
+bool MobileVRInterface::is_stereo() {
+	// needs stereo...
+	return true;
+};
+
+bool MobileVRInterface::is_initialized() {
+	return (initialized);
+};
+
+bool MobileVRInterface::initialize() {
+	ARVRServer *arvr_server = ARVRServer::get_singleton();
+	ERR_FAIL_NULL_V(arvr_server, false);
+
+	if (!initialized) {
+		// reset our sensor data and orientation
+		mag_count = 0;
+		has_gyro = false;
+		sensor_first = true;
+		mag_next_min = Vector3(10000, 10000, 10000);
+		mag_next_max = Vector3(-10000, -10000, -10000);
+		mag_current_min = Vector3(0, 0, 0);
+		mag_current_max = Vector3(0, 0, 0);
+
+		// reset our orientation
+		orientation = Basis();
+
+		// make this our primary interface
+		arvr_server->set_primary_interface(this);
+
+		last_ticks = OS::get_singleton()->get_ticks_usec();
+		;
+		initialized = true;
+	};
+
+	return true;
+};
+
+void MobileVRInterface::uninitialize() {
+	if (initialized) {
+		ARVRServer *arvr_server = ARVRServer::get_singleton();
+		if (arvr_server != NULL) {
+			// no longer our primary interface
+			arvr_server->clear_primary_interface_if(this);
+		}
+
+		initialized = false;
+	};
+};
+
+Size2 MobileVRInterface::get_recommended_render_targetsize() {
+	_THREAD_SAFE_METHOD_
+
+	// we use half our window size
+	Size2 target_size = OS::get_singleton()->get_window_size();
+	target_size.x *= 0.5 * oversample;
+	target_size.y *= oversample;
+
+	return target_size;
+};
+
+Transform MobileVRInterface::get_transform_for_eye(ARVRInterface::Eyes p_eye, const Transform &p_cam_transform) {
+	_THREAD_SAFE_METHOD_
+
+	Transform transform_for_eye;
+
+	ARVRServer *arvr_server = ARVRServer::get_singleton();
+	ERR_FAIL_NULL_V(arvr_server, transform_for_eye);
+
+	if (initialized) {
+		float world_scale = arvr_server->get_world_scale();
+
+		// we don't need to check for the existance of our HMD, doesn't effect our values...
+		// note * 0.01 to convert cm to m and * 0.5 as we're moving half in each direction...
+		if (p_eye == ARVRInterface::EYE_LEFT) {
+			transform_for_eye.origin.x = -(intraocular_dist * 0.01 * 0.5 * world_scale);
+		} else if (p_eye == ARVRInterface::EYE_RIGHT) {
+			transform_for_eye.origin.x = intraocular_dist * 0.01 * 0.5 * world_scale;
+		} else {
+			// for mono we don't reposition, we want our center position.
+		};
+
+		// just scale our origin point of our transform
+		Transform hmd_transform;
+		hmd_transform.basis = orientation;
+		hmd_transform.origin = Vector3(0.0, eye_height * world_scale, 0.0);
+
+		transform_for_eye = p_cam_transform * (arvr_server->get_reference_frame()) * hmd_transform * transform_for_eye;
+	} else {
+		// huh? well just return what we got....
+		transform_for_eye = p_cam_transform;
+	};
+
+	return transform_for_eye;
+};
+
+CameraMatrix MobileVRInterface::get_projection_for_eye(ARVRInterface::Eyes p_eye, real_t p_aspect, real_t p_z_near, real_t p_z_far) {
+	_THREAD_SAFE_METHOD_
+
+	CameraMatrix eye;
+
+	if (p_eye == ARVRInterface::EYE_MONO) {
+		///@TODO for now hardcode some of this, what is really needed here is that this needs to be in sync with the real cameras properties
+		// which probably means implementing a specific class for iOS and Android. For now this is purely here as an example.
+		// Note also that if you use a normal viewport with AR/VR turned off you can still use the tracker output of this interface
+		// to position a stock standard Godot camera and have control over this.
+		// This will make more sense when we implement ARkit on iOS (probably a separate interface).
+		eye.set_perspective(60.0, p_aspect, p_z_near, p_z_far, false);
+	} else {
+		eye.set_for_hmd(p_eye == ARVRInterface::EYE_LEFT ? 1 : 2, p_aspect, intraocular_dist, display_width, display_to_lens, oversample, p_z_near, p_z_far);
+	};
+
+	return eye;
+};
+
+void MobileVRInterface::commit_for_eye(ARVRInterface::Eyes p_eye, RID p_render_target, const Rect2 &p_screen_rect) {
+	_THREAD_SAFE_METHOD_
+
+	// We must have a valid render target
+	ERR_FAIL_COND(!p_render_target.is_valid());
+
+	// Because we are rendering to our device we must use our main viewport!
+	ERR_FAIL_COND(p_screen_rect == Rect2());
+
+	float offset_x = 0.0;
+	float aspect_ratio = 0.5 * p_screen_rect.size.x / p_screen_rect.size.y;
+	Vector2 eye_center;
+
+	if (p_eye == ARVRInterface::EYE_LEFT) {
+		offset_x = -1.0;
+		eye_center.x = ((-intraocular_dist / 2.0) + (display_width / 4.0)) / (display_width / 2.0);
+	} else if (p_eye == ARVRInterface::EYE_RIGHT) {
+		eye_center.x = ((intraocular_dist / 2.0) - (display_width / 4.0)) / (display_width / 2.0);
+	}
+
+	// unset our render target so we are outputting to our main screen by making RasterizerStorageGLES3::system_fbo our current FBO
+	VSG::rasterizer->set_current_render_target(RID());
+
+	// now output to screen
+	//	VSG::rasterizer->blit_render_target_to_screen(p_render_target, screen_rect, 0);
+
+	// get our render target
+	RID eye_texture = VSG::storage->render_target_get_texture(p_render_target);
+	uint32_t texid = VS::get_singleton()->texture_get_texid(eye_texture);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, texid);
+
+	lens_shader.bind();
+	lens_shader.set_uniform(LensDistortedShaderGLES3::OFFSET_X, offset_x);
+	lens_shader.set_uniform(LensDistortedShaderGLES3::K1, k1);
+	lens_shader.set_uniform(LensDistortedShaderGLES3::K2, k2);
+	lens_shader.set_uniform(LensDistortedShaderGLES3::EYE_CENTER, eye_center);
+	lens_shader.set_uniform(LensDistortedShaderGLES3::UPSCALE, oversample);
+	lens_shader.set_uniform(LensDistortedShaderGLES3::ASPECT_RATIO, aspect_ratio);
+
+	glBindVertexArray(half_screen_array);
+	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+	glBindVertexArray(0);
+};
+
+void MobileVRInterface::process() {
+	_THREAD_SAFE_METHOD_
+
+	if (initialized) {
+		set_position_from_sensors();
+	};
+};
+
+MobileVRInterface::MobileVRInterface() {
+	initialized = false;
+
+	// Just set some defaults for these. At some point we need to look at adding a lookup table for common device + headset combos and/or support reading cardboard QR codes
+	eye_height = 1.85;
+	intraocular_dist = 6.0;
+	display_width = 13.0;
+	display_to_lens = 4.0;
+	oversample = 1.5;
+	k1 = 0.22;
+	k2 = 0.23;
+	last_ticks = 0;
+
+	// create our shader stuff
+	lens_shader.init();
+
+	{
+		glGenBuffers(1, &half_screen_quad);
+		glBindBuffer(GL_ARRAY_BUFFER, half_screen_quad);
+		{
+			const float qv[16] = {
+				0, -1,
+				-1, -1,
+				0, 1,
+				-1, 1,
+				1, 1,
+				1, 1,
+				1, -1,
+				1, -1,
+			};
+
+			glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 16, qv, GL_STATIC_DRAW);
+		}
+
+		glBindBuffer(GL_ARRAY_BUFFER, 0); //unbind
+
+		glGenVertexArrays(1, &half_screen_array);
+		glBindVertexArray(half_screen_array);
+		glBindBuffer(GL_ARRAY_BUFFER, half_screen_quad);
+		glVertexAttribPointer(VS::ARRAY_VERTEX, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4, 0);
+		glEnableVertexAttribArray(0);
+		glVertexAttribPointer(VS::ARRAY_TEX_UV, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4, ((uint8_t *)NULL) + 8);
+		glEnableVertexAttribArray(4);
+		glBindVertexArray(0);
+		glBindBuffer(GL_ARRAY_BUFFER, 0); //unbind
+	}
+};
+
+MobileVRInterface::~MobileVRInterface() {
+	// and make sure we cleanup if we haven't already
+	if (is_initialized()) {
+		uninitialize();
+	};
+};
diff --git a/modules/mobile_vr/mobile_interface.h b/modules/mobile_vr/mobile_interface.h
new file mode 100644
index 0000000000..dfe3cd200e
--- /dev/null
+++ b/modules/mobile_vr/mobile_interface.h
@@ -0,0 +1,155 @@
+/*************************************************************************/
+/*  mobile_interface.h                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                    http://www.godotengine.org                         */
+/*************************************************************************/
+/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+#ifndef MOBILE_VR_INTERFACE_H
+#define MOBILE_VR_INTERFACE_H
+
+#include "servers/arvr/arvr_interface.h"
+#include "servers/arvr/arvr_positional_tracker.h"
+
+#include "shaders/lens_distorted.glsl.gen.h"
+
+/**
+	@author Bastiaan Olij <mux213@gmail.com>
+
+	The mobile interface is a native VR interface that can be used on Android and iOS phones.
+	It contains a basic implementation supporting 3DOF tracking if a gyroscope and accelerometer are
+	present and sets up the proper projection matrices based on the values provided.
+
+	We're planning to eventually do separate interfaces towards mobile SDKs that have far more capabilities and
+	do not rely on the user providing most of these settings (though enhancing this with auto detection features
+	based on the device we're running on would be cool). I'm mostly adding this as an example or base plate for
+	more advanced interfaces.
+*/
+
+class MobileVRInterface : public ARVRInterface {
+	GDCLASS(MobileVRInterface, ARVRInterface);
+
+private:
+	bool initialized;
+	Basis orientation;
+	float eye_height;
+	uint64_t last_ticks;
+
+	LensDistortedShaderGLES3 lens_shader;
+	GLuint half_screen_quad;
+	GLuint half_screen_array;
+
+	real_t intraocular_dist;
+	real_t display_width;
+	real_t display_to_lens;
+	real_t oversample;
+
+	//@TODO not yet used, these are needed in our distortion shader...
+	real_t k1;
+	real_t k2;
+
+	/*
+		logic for processing our sensor data, this was originally in our positional tracker logic but I think
+		that doesn't make sense in hindsight. It only makes marginally more sense to park it here for now,
+		this probably deserves an object of its own
+	*/
+	Vector3 scale_magneto(const Vector3 &p_magnetometer);
+	Basis combine_acc_mag(const Vector3 &p_grav, const Vector3 &p_magneto);
+
+	int mag_count;
+	bool has_gyro;
+	bool sensor_first;
+	Vector3 last_accerometer_data;
+	Vector3 last_magnetometer_data;
+	Vector3 mag_current_min;
+	Vector3 mag_current_max;
+	Vector3 mag_next_min;
+	Vector3 mag_next_max;
+
+	///@TODO a few support functions for trackers, most are math related and should likely be moved elsewhere
+	float floor_decimals(float p_value, float p_decimals) {
+		float power_of_10 = pow(10.0, p_decimals);
+		return floor(p_value * power_of_10) / power_of_10;
+	};
+
+	Vector3 floor_decimals(const Vector3 &p_vector, float p_decimals) {
+		return Vector3(floor_decimals(p_vector.x, p_decimals), floor_decimals(p_vector.y, p_decimals), floor_decimals(p_vector.z, p_decimals));
+	};
+
+	Vector3 low_pass(const Vector3 &p_vector, const Vector3 &p_last_vector, float p_factor) {
+		return p_vector + (p_factor * (p_last_vector - p_vector));
+	};
+
+	Vector3 scrub(const Vector3 &p_vector, const Vector3 &p_last_vector, float p_decimals, float p_factor) {
+		return low_pass(floor_decimals(p_vector, p_decimals), p_last_vector, p_factor);
+	};
+
+	void set_position_from_sensors();
+
+protected:
+	static void _bind_methods();
+
+public:
+	void set_iod(const real_t p_iod);
+	real_t get_iod() const;
+
+	void set_display_width(const real_t p_display_width);
+	real_t get_display_width() const;
+
+	void set_display_to_lens(const real_t p_display_to_lens);
+	real_t get_display_to_lens() const;
+
+	void set_oversample(const real_t p_oversample);
+	real_t get_oversample() const;
+
+	void set_k1(const real_t p_k1);
+	real_t get_k1() const;
+
+	void set_k2(const real_t p_k2);
+	real_t get_k2() const;
+
+	virtual StringName get_name() const;
+
+	virtual bool is_installed();
+	virtual bool hmd_is_present();
+	virtual bool supports_hmd();
+
+	virtual bool is_initialized();
+	virtual bool initialize();
+	virtual void uninitialize();
+
+	virtual Size2 get_recommended_render_targetsize();
+	virtual bool is_stereo();
+	virtual Transform get_transform_for_eye(ARVRInterface::Eyes p_eye, const Transform &p_cam_transform);
+	virtual CameraMatrix get_projection_for_eye(ARVRInterface::Eyes p_eye, real_t p_aspect, real_t p_z_near, real_t p_z_far);
+	virtual void commit_for_eye(ARVRInterface::Eyes p_eye, RID p_render_target, const Rect2 &p_screen_rect);
+
+	virtual void process();
+
+	MobileVRInterface();
+	~MobileVRInterface();
+};
+
+#endif // MOBILE_VR_INTERFACE_H
diff --git a/modules/mobile_vr/register_types.cpp b/modules/mobile_vr/register_types.cpp
new file mode 100644
index 0000000000..f742ecbf00
--- /dev/null
+++ b/modules/mobile_vr/register_types.cpp
@@ -0,0 +1,43 @@
+/*************************************************************************/
+/*  register_types.cpp                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+#include "register_types.h"
+
+#include "mobile_interface.h"
+
+void register_mobile_vr_types() {
+	ClassDB::register_class<MobileVRInterface>();
+
+	Ref<MobileVRInterface> mobile_vr;
+	mobile_vr.instance();
+	ARVRServer::get_singleton()->add_interface(mobile_vr);
+}
+
+void unregister_mobile_vr_types() {
+}
diff --git a/modules/mobile_vr/register_types.h b/modules/mobile_vr/register_types.h
new file mode 100644
index 0000000000..a492fff397
--- /dev/null
+++ b/modules/mobile_vr/register_types.h
@@ -0,0 +1,31 @@
+/*************************************************************************/
+/*  register_types.h                                                     */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+void register_mobile_vr_types();
+void unregister_mobile_vr_types();
diff --git a/modules/mobile_vr/shaders/SCsub b/modules/mobile_vr/shaders/SCsub
new file mode 100644
index 0000000000..cf53c9ebe0
--- /dev/null
+++ b/modules/mobile_vr/shaders/SCsub
@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+
+Import('env')
+
+if 'GLES3_GLSL' in env['BUILDERS']:
+    env.GLES3_GLSL('lens_distorted.glsl');
+
diff --git a/modules/mobile_vr/shaders/lens_distorted.glsl b/modules/mobile_vr/shaders/lens_distorted.glsl
new file mode 100644
index 0000000000..5a2975d737
--- /dev/null
+++ b/modules/mobile_vr/shaders/lens_distorted.glsl
@@ -0,0 +1,59 @@
+[vertex]
+
+layout(location=0) in highp vec4 vertex_attrib;
+layout(location=4) in vec2 uv_in;
+
+uniform float offset_x;
+
+out vec2 uv_interp;
+
+void main() {
+
+  uv_interp = uv_in;
+  gl_Position = vec4(vertex_attrib.x + offset_x, vertex_attrib.y, 0.0, 1.0);
+}
+
+[fragment]
+
+uniform sampler2D source; //texunit:0
+
+uniform vec2 eye_center;
+uniform float k1;
+uniform float k2;
+uniform float upscale;
+uniform float aspect_ratio;
+
+in vec2 uv_interp;
+
+layout(location = 0) out vec4 frag_color;
+
+void main() {
+  vec2 coords = uv_interp;
+  vec2 offset = coords - eye_center;
+
+  // take aspect ratio into account
+  offset.y /= aspect_ratio;
+
+  // distort 
+  vec2 offset_sq = offset * offset;
+  float radius_sq = offset_sq.x + offset_sq.y;
+  float radius_s4 = radius_sq * radius_sq;
+  float distortion_scale = 1.0 + (k1 * radius_sq) + (k2 * radius_s4);
+  offset *= distortion_scale;
+
+  // reapply aspect ratio
+  offset.y *= aspect_ratio;
+
+  // add our eye center back in
+  coords = offset + eye_center;
+  coords /= upscale;
+
+  // and check our color
+  if (coords.x < -1.0 || coords.y < -1.0 || coords.x > 1.0 || coords.y > 1.0) {
+    frag_color = vec4(0.0, 0.0, 0.0, 1.0);
+  } else {
+    coords = (coords + vec2(1.0)) / vec2(2.0);
+    frag_color = textureLod(source, coords, 0.0);
+  }
+}
+