monado/src/xrt/auxiliary/math/m_base.cpp

// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Base implementations for math library.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @author Ryan Pavlik <ryan.pavlik@collabora.com>
 * @author Moses Turner <mosesturner@protonmail.com>
 * @ingroup aux_math
 */

#include "math/m_api.h"
#include "math/m_eigen_interop.hpp"

#include <Eigen/Core>
#include <Eigen/Geometry>

#include <assert.h>

using namespace xrt::auxiliary::math;

/*
 *
 * Copy helpers.
 *
 */

static inline Eigen::Quaternionf
copy(const struct xrt_quat &q)
{
	// Eigen constructor order is different from XRT, OpenHMD and OpenXR!
	//  Eigen: `float w, x, y, z`.
	// OpenXR: `float x, y, z, w`.
	return Eigen::Quaternionf(q.w, q.x, q.y, q.z);
}

static inline Eigen::Quaternionf
copy(const struct xrt_quat *q)
{
	return copy(*q);
}

static inline Eigen::Vector3f
copy(const struct xrt_vec3 &v)
{
	return Eigen::Vector3f(v.x, v.y, v.z);
}

static inline Eigen::Vector3f
copy(const struct xrt_vec3 *v)
{
	return copy(*v);
}

static inline Eigen::Matrix3f
copy(const struct xrt_matrix_3x3 *m)
{
	Eigen::Matrix3f res;
	// clang-format off
	res << m->v[0], m->v[3], m->v[6],
	       m->v[1], m->v[4], m->v[7],
	       m->v[2], m->v[5], m->v[8];
	// clang-format on
	return res;
}

static inline Eigen::Matrix4f
copy(const struct xrt_matrix_4x4 *m)
{
	Eigen::Matrix4f res;
	// clang-format off
	res << m->v[0], m->v[4], m->v[8],  m->v[12],
	       m->v[1], m->v[5], m->v[9],  m->v[13],
	       m->v[2], m->v[6], m->v[10], m->v[14],
	       m->v[3], m->v[7], m->v[11], m->v[15];
	// clang-format on
	return res;
}

/*
 *
 * Exported vector functions.
 *
 */

extern "C" bool
math_vec3_validate(const struct xrt_vec3 *vec3)
{
	assert(vec3 != NULL);

	return map_vec3(*vec3).allFinite();
}

extern "C" void
math_vec3_accum(const struct xrt_vec3 *additional, struct xrt_vec3 *inAndOut)
{
	assert(additional != NULL);
	assert(inAndOut != NULL);

	map_vec3(*inAndOut) += map_vec3(*additional);
}

extern "C" void
math_vec3_subtract(const struct xrt_vec3 *subtrahend, struct xrt_vec3 *inAndOut)
{
	assert(subtrahend != NULL);
	assert(inAndOut != NULL);

	map_vec3(*inAndOut) -= map_vec3(*subtrahend);
}

extern "C" void
math_vec3_scalar_mul(float scalar, struct xrt_vec3 *inAndOut)
{
	assert(inAndOut != NULL);

	map_vec3(*inAndOut) *= scalar;
}

extern "C" void
math_vec3_cross(const struct xrt_vec3 *l, const struct xrt_vec3 *r, struct xrt_vec3 *result)
{
	map_vec3(*result) = map_vec3(*l).cross(map_vec3(*r));
}

extern "C" void
math_vec3_normalize(struct xrt_vec3 *in)
{
	map_vec3(*in) = map_vec3(*in).normalized();
}

/*
 *
 * Exported quaternion functions.
 *
 */

extern "C" void
math_quat_from_angle_vector(float angle_rads, const struct xrt_vec3 *vector, struct xrt_quat *result)
{
	map_quat(*result) = Eigen::AngleAxisf(angle_rads, copy(vector));
}

extern "C" void
math_quat_from_matrix_3x3(const struct xrt_matrix_3x3 *mat, struct xrt_quat *result)
{
	Eigen::Matrix3f m;
	m << mat->v[0], mat->v[1], mat->v[2], mat->v[3], mat->v[4], mat->v[5], mat->v[6], mat->v[7], mat->v[8];

	Eigen::Quaternionf q(m);
	map_quat(*result) = q;
}

extern "C" void
math_quat_from_plus_x_z(const struct xrt_vec3 *plus_x, const struct xrt_vec3 *plus_z, struct xrt_quat *result)
{
	xrt_vec3 plus_y;
	math_vec3_cross(plus_z, plus_x, &plus_y);

	xrt_matrix_3x3 m = {{
	    plus_x->x,
	    plus_y.x,
	    plus_z->x,
	    plus_x->y,
	    plus_y.y,
	    plus_z->y,
	    plus_x->z,
	    plus_y.z,
	    plus_z->z,
	}};

	math_quat_from_matrix_3x3(&m, result);
}

static bool
quat_validate(const float precision, const struct xrt_quat *quat)
{
	assert(quat != NULL);
	auto rot = copy(*quat);


	/*
	 * This was originally squaredNorm, but that could result in a norm
	 * value that was further from 1.0f then FLOAT_EPSILON (two).
	 *
	 * Our tracking system would produce such orientations and looping those
	 * back into say a quad layer would cause this to fail. And even
	 * normalizing the quat would not fix this as normalizations uses
	 * non-squared "length" which does fall into the range and doesn't
	 * change the elements of the quat.
	 */
	auto norm = rot.norm();
	if (norm > 1.0f + precision || norm < 1.0f - precision) {
		return false;
	}

	// Technically not yet a required check, but easier to stop problems
	// now than once denormalized numbers pollute the rest of our state.
	// see https://gitlab.khronos.org/openxr/openxr/issues/922
	if (!rot.coeffs().allFinite()) {
		return false;
	}

	return true;
}

extern "C" bool
math_quat_validate(const struct xrt_quat *quat)
{
	const float FLOAT_EPSILON = Eigen::NumTraits<float>::epsilon();
	return quat_validate(FLOAT_EPSILON, quat);
}

extern "C" bool
math_quat_validate_within_1_percent(const struct xrt_quat *quat)
{
	return quat_validate(0.01, quat);
}

extern "C" void
math_quat_invert(const struct xrt_quat *quat, struct xrt_quat *out_quat)
{
	map_quat(*out_quat) = map_quat(*quat).conjugate();
}

extern "C" void
math_quat_normalize(struct xrt_quat *inout)
{
	assert(inout != NULL);
	map_quat(*inout).normalize();
}

extern "C" bool
math_quat_ensure_normalized(struct xrt_quat *inout)
{
	assert(inout != NULL);

	if (math_quat_validate(inout))
		return true;

	const float FLOAT_EPSILON = Eigen::NumTraits<float>::epsilon();
	const float TOLERANCE = FLOAT_EPSILON * 5;

	auto rot = copy(*inout);
	auto norm = rot.norm();
	if (norm > 1.0f + TOLERANCE || norm < 1.0f - TOLERANCE) {
		return false;
	}

	map_quat(*inout).normalize();
	return true;
}


extern "C" void
math_quat_rotate(const struct xrt_quat *left, const struct xrt_quat *right, struct xrt_quat *result)
{
	assert(left != NULL);
	assert(right != NULL);
	assert(result != NULL);

	auto l = copy(left);
	auto r = copy(right);

	auto q = l * r;

	map_quat(*result) = q;
}

extern "C" void
math_quat_rotate_vec3(const struct xrt_quat *left, const struct xrt_vec3 *right, struct xrt_vec3 *result)
{
	assert(left != NULL);
	assert(right != NULL);
	assert(result != NULL);

	auto l = copy(left);
	auto r = copy(right);

	auto v = l * r;

	map_vec3(*result) = v;
}

extern "C" void
math_quat_rotate_derivative(const struct xrt_quat *quat, const struct xrt_vec3 *deriv, struct xrt_vec3 *result)
{
	assert(quat != NULL);
	assert(deriv != NULL);
	assert(result != NULL);

	auto l = copy(quat);
	auto m = Eigen::Quaternionf(0.0f, deriv->x, deriv->y, deriv->z);
	auto r = l.conjugate();

	auto v = l * m * r;

	struct xrt_vec3 ret = {v.x(), v.y(), v.z()};
	*result = ret;
}

extern "C" void
math_quat_slerp(const struct xrt_quat *left, const struct xrt_quat *right, float t, struct xrt_quat *result)
{
	assert(left != NULL);
	assert(right != NULL);
	assert(result != NULL);

	auto l = copy(left);
	auto r = copy(right);

	map_quat(*result) = l.slerp(t, r);
}

/*
 *
 * Exported matrix functions.
 *
 */

void
math_matrix_2x2_multiply(const struct xrt_matrix_2x2 *left,
                         const struct xrt_matrix_2x2 *right,
                         struct xrt_matrix_2x2 *result)
{
	result->v[0] = left->v[0] * right->v[0] + left->v[1] * right->v[2];
	result->v[1] = left->v[0] * right->v[1] + left->v[1] * right->v[3];
	result->v[2] = left->v[2] * right->v[0] + left->v[3] * right->v[2];
	result->v[3] = left->v[2] * right->v[1] + left->v[3] * right->v[3];
}

extern "C" void
math_matrix_3x3_transform_vec3(const struct xrt_matrix_3x3 *left, const struct xrt_vec3 *right, struct xrt_vec3 *result)
{
	Eigen::Matrix3f m;
	m << left->v[0], left->v[1], left->v[2], // 1
	    left->v[3], left->v[4], left->v[5],  // 2
	    left->v[6], left->v[7], left->v[8];  // 3

	map_vec3(*result) = m * copy(right);
}

extern "C" void
math_matrix_3x3_multiply(const struct xrt_matrix_3x3 *left,
                         const struct xrt_matrix_3x3 *right,
                         struct xrt_matrix_3x3 *result)
{
	result->v[0] = left->v[0] * right->v[0] + left->v[1] * right->v[3] + left->v[2] * right->v[6];
	result->v[1] = left->v[0] * right->v[1] + left->v[1] * right->v[4] + left->v[2] * right->v[7];
	result->v[2] = left->v[0] * right->v[2] + left->v[1] * right->v[5] + left->v[2] * right->v[8];

	result->v[3] = left->v[3] * right->v[0] + left->v[4] * right->v[3] + left->v[5] * right->v[6];
	result->v[4] = left->v[3] * right->v[1] + left->v[4] * right->v[4] + left->v[5] * right->v[7];
	result->v[5] = left->v[3] * right->v[2] + left->v[4] * right->v[5] + left->v[5] * right->v[8];

	result->v[6] = left->v[6] * right->v[0] + left->v[7] * right->v[3] + left->v[8] * right->v[6];
	result->v[7] = left->v[6] * right->v[1] + left->v[7] * right->v[4] + left->v[8] * right->v[7];
	result->v[8] = left->v[6] * right->v[2] + left->v[7] * right->v[5] + left->v[8] * right->v[8];
}

extern "C" void
math_matrix_3x3_inverse(const struct xrt_matrix_3x3 *in, struct xrt_matrix_3x3 *result)
{
	Eigen::Matrix3f m = copy(in);
	map_matrix_3x3(*result) = m.inverse();
}

void
math_matrix_4x4_identity(struct xrt_matrix_4x4 *result)
{
	map_matrix_4x4(*result) = Eigen::Matrix4f::Identity();
}

void
math_matrix_4x4_multiply(const struct xrt_matrix_4x4 *left,
                         const struct xrt_matrix_4x4 *right,
                         struct xrt_matrix_4x4 *result)
{
	map_matrix_4x4(*result) = copy(left) * copy(right);
}

void
math_matrix_4x4_view_from_pose(const struct xrt_pose *pose, struct xrt_matrix_4x4 *result)
{
	Eigen::Vector3f position = copy(&pose->position);
	Eigen::Quaternionf orientation = copy(&pose->orientation);

	Eigen::Translation3f translation(position);
	Eigen::Affine3f transformation = translation * orientation;

	map_matrix_4x4(*result) = transformation.matrix().inverse();
}

void
math_matrix_4x4_model(const struct xrt_pose *pose, const struct xrt_vec3 *size, struct xrt_matrix_4x4 *result)
{
	Eigen::Vector3f position = copy(&pose->position);
	Eigen::Quaternionf orientation = copy(&pose->orientation);

	auto scale = Eigen::Scaling(size->x, size->y, size->z);

	Eigen::Translation3f translation(position);
	Eigen::Affine3f transformation = translation * orientation * scale;

	map_matrix_4x4(*result) = transformation.matrix();
}

void
math_matrix_4x4_inverse_view_projection(const struct xrt_matrix_4x4 *view,
                                        const struct xrt_matrix_4x4 *projection,
                                        struct xrt_matrix_4x4 *result)
{
	Eigen::Matrix4f v = copy(view);
	Eigen::Matrix4f v3 = Eigen::Matrix4f::Identity();
	v3.block<3, 3>(0, 0) = v.block<3, 3>(0, 0);
	Eigen::Matrix4f vp = copy(projection) * v3;
	map_matrix_4x4(*result) = vp.inverse();
}

/*
 *
 * Exported pose functions.
 *
 */

extern "C" bool
math_pose_validate(const struct xrt_pose *pose)
{
	assert(pose != NULL);

	return math_vec3_validate(&pose->position) && math_quat_validate(&pose->orientation);
}

extern "C" void
math_pose_invert(const struct xrt_pose *pose, struct xrt_pose *outPose)
{
	assert(pose != NULL);
	assert(outPose != NULL);

	// Store results to temporary locals so we can do this "in-place"
	// (pose == outPose) if desired. Pure copies here.
	Eigen::Vector3f newPosition = position(*pose);
	Eigen::Quaternionf newOrientation = orientation(*pose);

	// Conjugate legal here since pose must be normalized/unit length.
	newOrientation = newOrientation.conjugate();
	// Use the newly inverted rotation, to rotate position.
	newPosition = -(newOrientation * newPosition);

	position(*outPose) = newPosition;
	orientation(*outPose) = newOrientation;
}

extern "C" void
math_pose_identity(struct xrt_pose *pose)
{
	pose->position.x = 0.0;
	pose->position.y = 0.0;
	pose->position.z = 0.0;
	pose->orientation.x = 0.0;
	pose->orientation.y = 0.0;
	pose->orientation.z = 0.0;
	pose->orientation.w = 1.0;
}

/*!
 * Return the result of transforming a point by a pose/transform.
 */
static inline Eigen::Vector3f
transform_point(const xrt_pose &transform, const xrt_vec3 &point)
{
	return orientation(transform) * map_vec3(point) + position(transform);
}

/*!
 * Return the result of transforming a pose by a pose/transform.
 */
static inline xrt_pose
transform_pose(const xrt_pose &transform, const xrt_pose &pose)
{
	xrt_pose ret;
	position(ret) = transform_point(transform, pose.position);
	orientation(ret) = orientation(transform) * orientation(pose);
	return ret;
}

extern "C" void
math_pose_transform(const struct xrt_pose *transform, const struct xrt_pose *pose, struct xrt_pose *outPose)
{
	assert(pose != NULL);
	assert(transform != NULL);
	assert(outPose != NULL);

	xrt_pose newPose = transform_pose(*transform, *pose);
	memcpy(outPose, &newPose, sizeof(xrt_pose));
}

extern "C" void
math_pose_transform_point(const struct xrt_pose *transform, const struct xrt_vec3 *point, struct xrt_vec3 *out_point)
{
	assert(transform != NULL);
	assert(point != NULL);
	assert(out_point != NULL);

	map_vec3(*out_point) = transform_point(*transform, *point);
}