117 lines
2.4 KiB
C
117 lines
2.4 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) 2005-2007 Warzone Resurrection 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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* Trig.c
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*
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* Trig lookup tables
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*
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*/
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/* Allow frame header files to be singly included */
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#define FRAME_LIB_INCLUDE
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#include <assert.h>
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#include <stdlib.h>
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#include <math.h>
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#include "types.h"
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#include "debug.h"
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#include "trig.h"
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/* Number of steps between -1 and 1 for the inverse tables */
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#define TRIG_ACCURACY 4096
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#define TRIG_ACCMASK 0x0fff
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static float aSin[2*TRIG_DEGREES];
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static float aCos[2*TRIG_DEGREES];
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static float aInvCos[TRIG_ACCURACY];
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static float aInvSin[TRIG_ACCURACY];
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/* Initialise the Trig tables */
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BOOL trigInitialise(void)
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{
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float val = 0.0f, inc = 2.0f * M_PI / TRIG_DEGREES;
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int i;
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// Initialise the tables
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for (i = 0; i < TRIG_DEGREES; i++)
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{
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aSin[i] = sinf(val);
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aCos[i] = cosf(val);
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aSin[TRIG_DEGREES+i] = aSin[i];
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aCos[TRIG_DEGREES+i] = aCos[i];
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val += inc;
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}
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inc = 2.0f / (TRIG_ACCURACY-1);
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val = -1;
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for (i = 0; i < TRIG_ACCURACY; i++)
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{
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aInvSin[i] = asinf(val) * (float)TRIG_DEGREES / (2.0f * (float)M_PI);
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aInvCos[i] = acosf(val) * (float)TRIG_DEGREES / (2.0f * (float)M_PI);
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val += inc;
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}
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return true;
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}
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/* Shutdown the trig tables */
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void trigShutDown(void)
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{}
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/* Access the trig tables */
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float trigSin(int angle)
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{
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return aSin[angle % TRIG_DEGREES + TRIG_DEGREES];
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}
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float trigCos(int angle)
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{
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return aCos[angle % TRIG_DEGREES + TRIG_DEGREES];
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}
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float trigInvSin(float val)
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{
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SDWORD index = (val+1) * (TRIG_ACCURACY-1) / 2;
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return aInvSin[index & TRIG_ACCMASK];
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}
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float trigInvCos(float val)
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{
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SDWORD index = (val+1) * (TRIG_ACCURACY-1) / 2;
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return aInvCos[index & TRIG_ACCMASK];
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}
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/* Fast lookup sqrt */
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float trigIntSqrt(unsigned int val)
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{
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return sqrtf(val);
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}
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