84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
/* Copyright (C) 2010 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "precompiled.h"
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#include "Fixed.h"
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#include "ps/CStr.h"
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template<>
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CFixed_15_16 CFixed_15_16::FromString(const CStr8& s)
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{
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return FromDouble(s.ToDouble()); // TODO: shouldn't use floats here
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}
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template<>
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CFixed_15_16 CFixed_15_16::FromString(const CStrW& s)
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{
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return FromDouble(s.ToDouble()); // TODO: shouldn't use floats here
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}
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// Based on http://www.dspguru.com/dsp/tricks/fixed-point-atan2-with-self-normalization
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CFixed_15_16 atan2_approx(CFixed_15_16 y, CFixed_15_16 x)
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{
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CFixed_15_16 zero;
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// Special case to avoid division-by-zero
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if (x.IsZero() && y.IsZero())
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return zero;
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CFixed_15_16 c1;
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c1.SetInternalValue(51472); // pi/4 << 16
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CFixed_15_16 c2;
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c2.SetInternalValue(154415); // 3*pi/4 << 16
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CFixed_15_16 abs_y = y.Absolute();
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CFixed_15_16 angle;
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if (x >= zero)
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{
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CFixed_15_16 r = (x - abs_y) / (x + abs_y);
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angle = c1 - c1.Multiply(r);
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}
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else
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{
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CFixed_15_16 r = (x + abs_y) / (abs_y - x);
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angle = c2 - c1.Multiply(r);
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}
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if (y < zero)
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return -angle;
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else
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return angle;
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}
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template<>
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CFixed_15_16 CFixed_15_16::Pi()
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{
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return CFixed_15_16(205887); // = pi << 16
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}
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void sincos_approx(CFixed_15_16 a, CFixed_15_16& sin_out, CFixed_15_16& cos_out)
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{
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// XXX: mustn't use floating-point here - need a fixed-point emulation
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sin_out = CFixed_15_16::FromDouble(sin(a.ToDouble()));
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cos_out = CFixed_15_16::FromDouble(cos(a.ToDouble()));
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}
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