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/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
This file is part of Quake III Arena source code.
Quake III Arena source code is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
Quake III Arena source code is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
===========================================================================
*/
// tr_noise.c
#include "tr_local.h"
#define NOISE_SIZE 256
#define NOISE_MASK ( NOISE_SIZE - 1 )
#define VAL( a ) s_noise_perm[ ( a ) & ( NOISE_MASK )]
#define INDEX( x, y, z, t ) VAL( x + VAL( y + VAL( z + VAL( t ) ) ) )
static float s_noise_table[NOISE_SIZE];
static int s_noise_perm[NOISE_SIZE];
#define LERP( a, b, w ) ( a * ( 1.0f - w ) + b * w )
static float GetNoiseValue( int x, int y, int z, int t )
{
int index = INDEX( ( int ) x, ( int ) y, ( int ) z, ( int ) t );
return s_noise_table[index];
}
void R_NoiseInit( void )
{
int i;
srand( 1001 );
for ( i = 0; i < NOISE_SIZE; i++ )
{
s_noise_table[i] = ( float ) ( ( ( rand() / ( float ) RAND_MAX ) * 2.0 - 1.0 ) );
s_noise_perm[i] = ( unsigned char ) ( rand() / ( float ) RAND_MAX * 255 );
}
}
float R_NoiseGet4f( float x, float y, float z, float t )
{
int i;
int ix, iy, iz, it;
float fx, fy, fz, ft;
float front[4];
float back[4];
float fvalue, bvalue, value[2], finalvalue;
ix = ( int ) floor( x );
fx = x - ix;
iy = ( int ) floor( y );
fy = y - iy;
iz = ( int ) floor( z );
fz = z - iz;
it = ( int ) floor( t );
ft = t - it;
for ( i = 0; i < 2; i++ )
{
front[0] = GetNoiseValue( ix, iy, iz, it + i );
front[1] = GetNoiseValue( ix+1, iy, iz, it + i );
front[2] = GetNoiseValue( ix, iy+1, iz, it + i );
front[3] = GetNoiseValue( ix+1, iy+1, iz, it + i );
back[0] = GetNoiseValue( ix, iy, iz + 1, it + i );
back[1] = GetNoiseValue( ix+1, iy, iz + 1, it + i );
back[2] = GetNoiseValue( ix, iy+1, iz + 1, it + i );
back[3] = GetNoiseValue( ix+1, iy+1, iz + 1, it + i );
fvalue = LERP( LERP( front[0], front[1], fx ), LERP( front[2], front[3], fx ), fy );
bvalue = LERP( LERP( back[0], back[1], fx ), LERP( back[2], back[3], fx ), fy );
value[i] = LERP( fvalue, bvalue, fz );
}
finalvalue = LERP( value[0], value[1], ft );
return finalvalue;
}
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