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97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
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/*
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===========================================================================
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Copyright (C) 1999-2005 Id Software, Inc.
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Copyright (C) 2006 Robert Beckebans <trebor_7@users.sourceforge.net>
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This file is part of XreaL source code.
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XreaL source code is free software; you can redistribute it
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and/or modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the License,
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or (at your option) any later version.
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XreaL source code is distributed in the hope that it will be
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useful, 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 XreaL source code; 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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// tr_noise.c
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#include "tr_local.h"
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#define NOISE_SIZE 256
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#define NOISE_MASK ( NOISE_SIZE - 1 )
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#define VAL( a ) s_noise_perm[ ( a ) & ( NOISE_MASK )]
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#define INDEX( x, y, z, t ) VAL( x + VAL( y + VAL( z + VAL( t ) ) ) )
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static float s_noise_table[NOISE_SIZE];
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static int s_noise_perm[NOISE_SIZE];
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#define LERP( a, b, w ) ( a * ( 1.0f - w ) + b * w )
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static float GetNoiseValue(int x, int y, int z, int t)
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{
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int index = INDEX((int)x, (int)y, (int)z, (int)t);
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return s_noise_table[index];
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}
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void R_NoiseInit(void)
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{
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int i;
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srand(1001);
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for(i = 0; i < NOISE_SIZE; i++)
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{
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s_noise_table[i] = (float)(((rand() / (float)RAND_MAX) * 2.0 - 1.0));
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s_noise_perm[i] = (unsigned char)(rand() / (float)RAND_MAX * 255);
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}
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}
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float R_NoiseGet4f(float x, float y, float z, float t)
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{
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int i;
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int ix, iy, iz, it;
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float fx, fy, fz, ft;
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float front[4];
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float back[4];
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float fvalue, bvalue, value[2], finalvalue;
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ix = (int)floor(x);
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fx = x - ix;
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iy = (int)floor(y);
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fy = y - iy;
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iz = (int)floor(z);
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fz = z - iz;
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it = (int)floor(t);
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ft = t - it;
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for(i = 0; i < 2; i++)
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{
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front[0] = GetNoiseValue(ix, iy, iz, it + i);
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front[1] = GetNoiseValue(ix + 1, iy, iz, it + i);
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front[2] = GetNoiseValue(ix, iy + 1, iz, it + i);
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front[3] = GetNoiseValue(ix + 1, iy + 1, iz, it + i);
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back[0] = GetNoiseValue(ix, iy, iz + 1, it + i);
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back[1] = GetNoiseValue(ix + 1, iy, iz + 1, it + i);
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back[2] = GetNoiseValue(ix, iy + 1, iz + 1, it + i);
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back[3] = GetNoiseValue(ix + 1, iy + 1, iz + 1, it + i);
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fvalue = LERP(LERP(front[0], front[1], fx), LERP(front[2], front[3], fx), fy);
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bvalue = LERP(LERP(back[0], back[1], fx), LERP(back[2], back[3], fx), fy);
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value[i] = LERP(fvalue, bvalue, fz);
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}
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finalvalue = LERP(value[0], value[1], ft);
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return finalvalue;
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}
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