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https://git.do.srb2.org/STJr/UltimateZoneBuilder.git
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146 lines
3.8 KiB
C++
146 lines
3.8 KiB
C++
/*
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** fastsin.h
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** a table/linear interpolation-based sine function that is both
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** precise and fast enough for most purposes.
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**
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**---------------------------------------------------------------------------
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** Copyright 2015 Christoph Oelckers
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** All rights reserved.
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**
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** Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions
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** are met:
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**
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** 1. Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** 2. Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in the
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** documentation and/or other materials provided with the distribution.
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** 3. The name of the author may not be used to endorse or promote products
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** derived from this software without specific prior written permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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** NOT 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 OF
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** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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**---------------------------------------------------------------------------
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**
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*/
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#pragma once
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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#ifdef WIN32
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#define FORCEINLINE __forceinline
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#else
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#define FORCEINLINE
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#endif
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// This uses a sine table with linear interpolation
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// For in-game calculations this is precise enough
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// and this code is more than 10x faster than the
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// Cephes sin and cos function.
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struct FFastTrig
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{
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static const int TBLPERIOD = 8192;
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static const int BITSHIFT = 19;
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static const int REMAINDER = (1 << BITSHIFT) - 1;
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float sinetable[2049];
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FORCEINLINE double sinq1(uint32_t bangle)
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{
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unsigned int index = bangle >> BITSHIFT;
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if ((bangle &= (REMAINDER)) == 0) // This is to avoid precision problems at 180 degrees
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{
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return double(sinetable[index]);
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}
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else
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{
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return (double(sinetable[index]) * (REMAINDER - bangle) + double(sinetable[index + 1]) * bangle) * (1. / REMAINDER);
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}
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}
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public:
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FFastTrig()
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{
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const double pimul = M_PI * 2 / TBLPERIOD;
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for (int i = 0; i < 2049; i++)
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{
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sinetable[i] = (float)std::sin(i * pimul);
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}
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}
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double sin(uint32_t bangle)
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{
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switch (bangle & 0xc0000000)
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{
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default:
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return sinq1(bangle);
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case 0x40000000:
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return sinq1(0x80000000 - bangle);
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case 0x80000000:
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return -sinq1(bangle - 0x80000000);
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case 0xc0000000:
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return -sinq1(0 - bangle);
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}
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}
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double cos(uint32_t bangle)
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{
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switch (bangle & 0xc0000000)
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{
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default:
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return sinq1(0x40000000 - bangle);
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case 0x40000000:
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return -sinq1(bangle - 0x40000000);
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case 0x80000000:
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return -sinq1(0xc0000000 - bangle);
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case 0xc0000000:
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return sinq1(bangle - 0xc0000000);
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}
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}
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};
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static FFastTrig fasttrig;
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// This must use xs_Float to guarantee proper integer wraparound.
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#define DEG2BAM(f) ((uint32_t)std::round((f) * (0x40000000/90.)))
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#define RAD2BAM(f) ((uint32_t)std::round((f) * (0x80000000/3.14159265358979323846)))
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inline double fastcosdeg(double v)
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{
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return fasttrig.cos(DEG2BAM(v));
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}
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inline double fastsindeg(double v)
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{
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return fasttrig.sin(DEG2BAM(v));
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}
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inline double fastcos(double v)
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{
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return fasttrig.cos(RAD2BAM(v));
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}
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inline double fastsin(double v)
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{
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return fasttrig.sin(RAD2BAM(v));
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}
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