111 lines
4.0 KiB
C++
111 lines
4.0 KiB
C++
/*
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---------------------------------------------------------------------------
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Open Asset Import Library (ASSIMP)
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---------------------------------------------------------------------------
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Copyright (c) 2006-2010, ASSIMP Development Team
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All rights reserved.
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Redistribution and use of this software in source and binary forms,
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with or without modification, are permitted provided that the following
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conditions are met:
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* Redistributions of source code must retain the above
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copyright notice, this list of conditions and the
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following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other
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materials provided with the distribution.
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* Neither the name of the ASSIMP team, nor the names of its
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contributors may be used to endorse or promote products
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derived from this software without specific prior
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written permission of the ASSIMP Development Team.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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---------------------------------------------------------------------------
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*/
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/** @file qnan.h
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* @brief Some utilities for our dealings with qnans.
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*
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* @note Some loaders use qnans to mark invalid values tempoarily, also
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* Assimp explicitly enforces undefined normals to be set to qnan.
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* qnan utilities are available in standard libraries (C99 for example)
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* but last time I checked compiler coverage was so bad that I decided
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* to reinvent the wheel.
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*/
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#ifndef AI_QNAN_H_INCLUDED
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#define AI_QNAN_H_INCLUDED
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// ---------------------------------------------------------------------------
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/** Data structure to represent the bit pattern of a 32 Bit
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* IEEE 754 floating-point number. */
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union _IEEESingle
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{
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float Float;
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struct
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{
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uint32_t Frac : 23;
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uint32_t Exp : 8;
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uint32_t Sign : 1;
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} IEEE;
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} ;
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// ---------------------------------------------------------------------------
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/** Check whether a given float is qNaN.
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* @param in Input value */
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AI_FORCE_INLINE bool is_qnan(float in)
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{
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// the straightforward solution does not work:
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// return (in != in);
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// compiler generates code like this
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// load <in> to <register-with-different-width>
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// compare <register-with-different-width> against <in>
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// FIXME: Use <float> stuff instead? I think fpclassify needs C99
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return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1 &&
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reinterpret_cast<_IEEESingle*>(&in)->IEEE.Frac);
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}
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// ---------------------------------------------------------------------------
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/** Check whether a float is NOT qNaN.
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* @param in Input value */
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AI_FORCE_INLINE bool is_not_qnan(float in)
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{
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return !is_qnan(in);
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}
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// ---------------------------------------------------------------------------
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/** @brief check whether a float is either NaN or (+/-) INF.
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*
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* Denorms return false, they're treated like normal values.
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* @param in Input value */
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AI_FORCE_INLINE bool is_special_float(float in)
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{
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return (reinterpret_cast<_IEEESingle*>(&in)->IEEE.Exp == (1u << 8)-1);
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}
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// ---------------------------------------------------------------------------
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/** @brief Get a fresh qnan. */
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AI_FORCE_INLINE float get_qnan()
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{
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return std::numeric_limits<float>::quiet_NaN();
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}
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#endif // !! AI_QNAN_H_INCLUDED
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