82 lines
2 KiB
C++
82 lines
2 KiB
C++
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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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float GetNoiseTime( int t )
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{
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int index = VAL( t );
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return (1 + 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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