66 lines
3.0 KiB
C++
66 lines
3.0 KiB
C++
#pragma once
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////////////////////////////////////////////////////////////////////////////////
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// The MIT License (MIT)
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//
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// Copyright (c) 2019 Nicholas Frechette & Realtime Math contributors
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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////////////////////////////////////////////////////////////////////////////////
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#include "rtm/math.h"
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#include "rtm/quatd.h"
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#include "rtm/vector4d.h"
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#include "rtm/impl/compiler_utils.h"
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RTM_IMPL_FILE_PRAGMA_PUSH
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namespace rtm
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{
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//////////////////////////////////////////////////////////////////////////
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// Returns the quaternion on the hypersphere with a positive [w] component
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// that represents the same 3D rotation as the input.
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//////////////////////////////////////////////////////////////////////////
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RTM_DISABLE_SECURITY_COOKIE_CHECK RTM_FORCE_INLINE quatd quat_ensure_positive_w(const quatd& input) RTM_NO_EXCEPT
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{
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return quat_get_w(input) >= 0.0 ? input : quat_neg(input);
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}
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//////////////////////////////////////////////////////////////////////////
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// Returns a quaternion constructed from a vector3 representing the [xyz]
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// components while reconstructing the [w] component by assuming it is positive.
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//////////////////////////////////////////////////////////////////////////
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RTM_DISABLE_SECURITY_COOKIE_CHECK RTM_FORCE_INLINE quatd quat_from_positive_w(const vector4d& input) RTM_NO_EXCEPT
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{
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const double input_x = vector_get_x(input);
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const double input_y = vector_get_y(input);
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const double input_z = vector_get_z(input);
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// Operation order is important here, due to rounding, ((1.0 - (X*X)) - Y*Y) - Z*Z is more accurate than 1.0 - dot3(xyz, xyz)
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const double w_squared = ((1.0 - (input_x * input_x)) - (input_y * input_y)) - (input_z * input_z);
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// w_squared can be negative either due to rounding or due to quantization imprecision, we take the absolute value
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// to ensure the resulting quaternion is always normalized with a positive W component
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const double w = scalar_sqrt(scalar_abs(w_squared));
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return quat_set_w(vector_to_quat(input), w);
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}
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}
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RTM_IMPL_FILE_PRAGMA_POP
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