54 lines
2.6 KiB
C
54 lines
2.6 KiB
C
/*
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This file is part of Warzone 2100.
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Copyright (C) 1999-2004 Eidos Interactive
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Copyright (C) 2005-2013 Warzone 2100 Project
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Warzone 2100 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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Warzone 2100 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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You should have received a copy of the GNU General Public License
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along with Warzone 2100; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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*
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* Interface to trig lookup tables.
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*/
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#ifndef _trig_h
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#define _trig_h
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#include "frame.h"
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/* Initialise the Trig tables */
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extern bool trigInitialise(void);
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// Deterministic trig functions.
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WZ_DECL_PURE int32_t iSin(uint16_t a); ///< Returns sin(a*2π >> 16) << 16, rounded to nearest integer. Used as the x component in this game.
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WZ_DECL_PURE int32_t iCos(uint16_t a); ///< Returns cos(a*2π >> 16) << 16, rounded to nearest integer. Used as the y component in this game.
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WZ_DECL_PURE int32_t iSinR(uint16_t a, int32_t r); ///< Returns r*sin(a*2π >> 16), with up to 16 bits precision.
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WZ_DECL_PURE int32_t iCosR(uint16_t a, int32_t r); ///< Returns r*cos(a*2π >> 16), with up to 16 bits precision.
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WZ_DECL_PURE int32_t iSinSR(int32_t a, int32_t s, int32_t r); ///< Returns r*sin(a*2π/s), with up to 16 bits precision.
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WZ_DECL_PURE int32_t iCosSR(int32_t a, int32_t s, int32_t r); ///< Returns r*cos(a*2π/s), with up to 16 bits precision.
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WZ_DECL_PURE uint16_t iAtan2(int32_t s, int32_t c); ///< Returns atan2(s, c)/2π << 16, with a small ±1.5 platform-independent error. Used as atan2(x, y) in this game.
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WZ_DECL_PURE int32_t iSqrt(uint32_t n); ///< Returns √(n), rounded down.
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WZ_DECL_PURE int32_t i64Sqrt(uint64_t n); ///< Returns √(n), rounded down.
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WZ_DECL_PURE int32_t iHypot(int32_t x, int32_t y); ///< Returns √(x² + y²), rounded down. In case of overflow, returns correct result cast to (int32_t).
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WZ_DECL_PURE int32_t iHypot3(int32_t x, int32_t y, int32_t z); ///< Returns √(x² + y² + z²), rounded down. In case of overflow, returns correct result cast to (int32_t).
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/// Returns the given angle, wrapped to the range [-180°; 180°) = [-32768; 32767].
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static inline WZ_DECL_CONST int32_t angleDelta(int32_t a)
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{
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return (int16_t)a; // Cast wrapping intended.
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}
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#endif
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