69 lines
1.8 KiB
C++
69 lines
1.8 KiB
C++
/*
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* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2011 Danny Robson <danny@nerdcruft.net>
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*/
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#include "quaternion.hpp"
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//-----------------------------------------------------------------------------
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using util::quaternion;
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//-----------------------------------------------------------------------------
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const quaternion quaternion::IDENTITY = { 1.0, 0.0, 0.0, 0.0 };
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//-----------------------------------------------------------------------------
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quaternion
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quaternion::rotation (double radians, vector<3> axis) {
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radians /= 2.0;
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axis.normalise ();
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return {
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cos (radians),
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axis.x * sin (radians),
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axis.y * sin (radians),
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axis.z * sin (radians)
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};
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}
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quaternion
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quaternion::rotation (vector<3> from, vector<3> to) {
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auto v = util::cross (from, to);
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return {
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acos (from.dot (to)),
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v.x,
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v.y,
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v.z
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};
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}
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quaternion
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quaternion::operator* (const quaternion &rhs) const {
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return {
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w * rhs.w - (x * rhs.x + y * rhs.y + z * rhs.z),
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w * rhs.x + rhs.w * x + y * rhs.z - z * rhs.y,
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w * rhs.y + rhs.w * y + z * rhs.x - x * rhs.z,
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w * rhs.z + rhs.w * z + x * rhs.y - y * rhs.x
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};
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}
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