Danny Robson
34788756d2
GCC produces ODR error when including paths of the form './foo' and 'foo' in the same binary. Rather than managing duplication we just universally pick the absolute form over the relative form.
286 lines
8.4 KiB
C++
286 lines
8.4 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2011-2016 Danny Robson <danny@nerdcruft.net>
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*/
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#include "quaternion.hpp"
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#include "debug.hpp"
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#include "vector.hpp"
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#include <cmath>
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///////////////////////////////////////////////////////////////////////////////
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using util::quaternion;
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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quaternion<T>
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quaternion<T>::angle_axis (const T radians, const vector<3,T> axis)
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{
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CHECK (is_normalised (axis));
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auto w = std::cos (radians / 2);
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auto xyz = std::sin (radians / 2) * axis;
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return {
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w, xyz.x, xyz.y, xyz.z
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};
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}
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//-----------------------------------------------------------------------------
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template <typename T>
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quaternion<T>
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quaternion<T>::from_euler (vector<3,T> angles)
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{
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auto half = angles / 2;
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auto c = cos (half);
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auto s = sin (half);
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return {
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c.x * c.y * c.z - s.x * s.y * s.z,
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s.x * c.y * c.z + c.x * s.y * s.z,
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c.x * s.y * c.z - s.x * c.y * s.z,
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c.x * c.y * s.z + s.x * s.y * c.z,
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};
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}
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///////////////////////////////////////////////////////////////////////////////
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// vector-to-vector rotation algorithm from:
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// http://lolengine.net/blog/2014/02/24/quaternion-from-two-vectors-final
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template <typename T>
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quaternion<T>
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quaternion<T>::from_to (const vector<3,T> u, const vector<3,T> v)
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{
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CHECK (is_normalised (u));
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CHECK (is_normalised (v));
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#if 0
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// Naive:
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auto cos_theta = dot (u, v);
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auto angle = std::acos (cos_theta);
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auto axis = normalised (cross (u, v));
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return angle_axis (angle, axis);
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#elif 1
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auto norm_u_norm_v = std::sqrt(dot(u, u) * dot(v, v));
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auto real_part = norm_u_norm_v + dot(u, v);
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util::vector<3,T> w;
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if (real_part < 1.e-6f * norm_u_norm_v)
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{
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/* If u and v are exactly opposite, rotate 180 degrees
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* around an arbitrary orthogonal axis. Axis normalisation
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* can happen later, when we normalise the quaternion. */
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real_part = 0.0f;
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w = std::abs(u.x) > std::abs(u.z) ?
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util::vector3<T> (-u.y, u.x, 0.f) :
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util::vector3<T> (0.f, -u.z, u.y);
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}
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else
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{
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/* Otherwise, build quaternion the standard way. */
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w = cross(u, v);
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}
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return normalised (util::quaternion<T> {real_part, w.x, w.y, w.z});
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#endif
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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quaternion<T>
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util::conjugate (quaternion<T> q)
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{
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return { q.w, -q.x, -q.y, -q.z };
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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quaternion<T>
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util::operator* (const quaternion<T> a, const quaternion<T> b)
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{
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return {
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a.w * b.w - a.x * b.x - a.y * b.y - a.z * b.z,
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a.w * b.x + a.x * b.w + a.y * b.z - a.z * b.y,
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a.w * b.y - a.x * b.z + a.y * b.w + a.z * b.x,
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a.w * b.z + a.x * b.y - a.y * b.x + a.z * b.w,
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};
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}
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//-----------------------------------------------------------------------------
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template <typename T>
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quaternion<T>&
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util::operator*= (quaternion<T> &a, const quaternion<T> b)
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{
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return a = a * b;
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}
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//-----------------------------------------------------------------------------
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template <typename T>
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quaternion<T>
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util::operator/ (const quaternion<T> a, const quaternion<T> b)
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{
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CHECK (is_normalised (a));
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CHECK (is_normalised (b));
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return quaternion<T> {
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a.w * b.w + a.x * b.x + a.y * b.y + a.z * b.z,
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- a.w * b.x + a.x * b.w + a.y * b.z - a.z * b.y,
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- a.w * b.y - a.x * b.z + a.y * b.w + a.z * b.x,
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- a.w * b.z + a.x * b.y - a.y * b.x + a.z * b.w,
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};
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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util::matrix4<T>
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quaternion<T>::as_matrix (void) const
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{
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CHECK (is_normalised (*this));
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const T wx = this->w * this->x, wy = this->w * this->y, wz = this->w * this->z;
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const T xx = this->x * this->x, xy = this->x * this->y, xz = this->x * this->z;
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const T yy = this->y * this->y, yz = this->y * this->z, zz = this->z * this->z;
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return { {
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{ 1 - 2 * (yy + zz), 2 * (xy - wz), 2 * (xz + wy), 0 },
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{ 2 * (xy + wz), 1 - 2 * (xx + zz), 2 * (yz - wx), 0 },
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{ 2 * (xz - wy), 2 * (yz + wx), 1 - 2 * (xx + yy), 0 },
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{ 0, 0, 0, 1 }
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} };
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}
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///////////////////////////////////////////////////////////////////////////////
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// https://gamedev.stackexchange.com/questions/28395/rotating-vector3-by-a-quaternion
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template <typename T>
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util::vector3<T>
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util::rotate (vector3<T> v, quaternion<T> q)
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{
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CHECK (is_normalised (v));
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CHECK (is_normalised (q));
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#if 0
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// Naive:
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quaternion<T> p { 0, v.x, v.y, v.z };
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auto p_ = q * p * conjugate (q);
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return { p_.x, p_.y, p_.z };
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#elif 1
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// This code actually matches the stackexchange link, but is longer than
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// the code below it (which also actually works)...
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const util::vector3<T> u { q.x, q.y, q.z };
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const auto s = q.w;
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return 2 * dot (u, v) * u
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+ (s * s - dot (u, u)) * v
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+ 2 * s * cross (u, v);
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#elif 0
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// I have no idea where this code is from or how it was derived...
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util::vector3<T> u { q.x, q.y, q.z };
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return v + 2 * cross (u, cross (u, v) + q.w * v);
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#endif
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}
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///////////////////////////////////////////////////////////////////////////////
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// based on the implementation at:
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// http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-17-quaternions/
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template <typename T>
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quaternion<T>
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quaternion<T>::look (vector<3,T> fwd, vector<3,T> up)
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{
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CHECK (is_normalised (fwd));
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CHECK (is_normalised (up));
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constexpr util::vector3<T> FWD { 0, 0, -1 };
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constexpr util::vector3<T> UP { 0, 1, 0 };
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// find the rotation from the world fwd to the object fwd
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auto q1 = from_to (FWD, fwd);
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// orthogonalise the up vector
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auto right = cross (fwd, up);
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auto orthup = normalised (cross (right, fwd));
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// recompute the up vector in object space
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auto newup = rotate (UP, q1);
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// find rotation from object up to world up
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auto q2 = from_to (newup, orthup);
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return q2 * q1;
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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bool
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util::almost_equal (quaternion<T> a, quaternion<T> b)
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{
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return almost_equal (a.w, b.w) &&
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almost_equal (a.x, b.x) &&
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almost_equal (a.y, b.y) &&
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almost_equal (a.z, b.z);
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}
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///////////////////////////////////////////////////////////////////////////////
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template <typename T>
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std::ostream&
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util::operator<< (std::ostream &os, const quaternion<T> q)
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{
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return os << "[" << q.w << ", " << q.x << ", " << q.y << ", " << q.z << "]";
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}
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///////////////////////////////////////////////////////////////////////////////
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namespace util::debug {
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template <typename T>
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struct validator<quaternion<T>> {
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static constexpr
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bool
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is_valid (const quaternion<T> &q)
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{
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return is_normalised (q);
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}
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};
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}
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///////////////////////////////////////////////////////////////////////////////
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#define INSTANTIATE(T) \
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template util::vector3<T> util::rotate (util::vector3<T>, util::quaternion<T>); \
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template quaternion<T> util::conjugate (quaternion<T>); \
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template quaternion<T> util::operator* (quaternion<T>, quaternion<T>); \
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template quaternion<T>& util::operator*= (quaternion<T>&, quaternion<T>); \
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template quaternion<T> util::operator/ (quaternion<T>, quaternion<T>); \
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template bool util::almost_equal (util::quaternion<T>, util::quaternion<T>); \
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template std::ostream& util::operator<< (std::ostream&, quaternion<T>); \
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template bool util::debug::is_valid(const quaternion<T>&); \
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template struct util::quaternion<T>;
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INSTANTIATE(float)
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INSTANTIATE(double)
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