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void Game::GetPreviousState( dens_prev, u_prev, v_prev );
{
}
void Game::DrawFluid( N, dens );
{
}
void diffuse
(
int N,
int b,
float * x,
float * x0,
float diff,
float dt
)
{
float a = dt * diff * N * N;
for( int k = 0; k < 20; k++ )
{
for( int i = 1; i <= N; i++ )
{
for( int j = 1; j <= N; j++ )
{
x[ IX(i,j) ] = ( x0[ IX(i,j) ] + a * ( x[ IX(i-1,j) ] +
x[ IX(i+1,j) ] +
x[ IX(i,j-1) ] +
x[ IX(i,j+1) ] ) ) / ( 1 + 4 * a );
}
}
set_bnd ( N, b, x );
}
}
void set_bnd( int N, int b, float * x )
{
for( int i = 1; i <= N; i++ )
{
x[ IX(0 ,i) ] = b == 1 ? –x[ IX(1,i) ] : x[ IX(1,i) ];
x[ IX(N+1,i) ] = b == 1 ? –x[ IX(N,i) ] : x[ IX(N,i) ];
x[ IX(i,0 ) ] = b == 2 ? –x[ IX(i,1) ] : x[ IX(i,1) ];
x[ IX(i,N+1) ] = b == 2 ? –x[ IX(i,N) ] : x[ IX(i,N) ];
}
x[IX(0 ,0 )] = 0.5*(x[IX(1,0 )]+x[IX(0 ,1)]);
x[IX(0 ,N+1)] = 0.5*(x[IX(1,N+1)]+x[IX(0 ,N )]);
x[IX(N+1,0 )] = 0.5*(x[IX(N,0 )]+x[IX(N+1,1)]);
x[IX(N+1,N+1)] = 0.5*(x[IX(N,N+1)]+x[IX(N+1,N )]);
}
void project
(
int N,
float * u,
float * v,
float * p,
float * div
)
{
float h = 1.0f / (float)N; // Calculate width of each cell
for ( int i = 1; i <= N; i++ )
{
for ( int j = 1; j <= N; j++ )
{
div[ IX(i,j) ] = -0.5 * h * ( u[IX(i+1,j)]-u[IX(i-1,j)] +
v[IX(i,j+1)]-v[IX(i,j-1)] );
p[ IX(i,j) ] = 0;
}
}
set_bnd ( N, 0, div );
set_bnd ( N, 0, p );
for( int k = 0; k < 20; k++ )
{
for( int i = 1; i <= N; i++ )
{
for( int j = 1; j <= N; j++ )
{
p[ IX(i,j) ] = ( div[ IX(i,j) ] +
p[ IX(i-1,j) ] +
p[ IX(i+1,j) ] +
p[ IX(i,j-1) ] +
p[ IX(i,j+1) ] ) / 4.0f;
}
}
set_bnd ( N, 0, p );
}
for( int i = 1; i <= N; i++ )
{
for( int j = 1; j <= N; j++ )
{
u[ IX(i,j) ] -= 0.5 * ( p[ IX(i+1,j) ] - p[ IX(i-1,j) ] ) / h;
v[ IX(i,j) ] -= 0.5 * ( p[ IX(i,j+1) ] - p[ IX(i,j-1) ] ) / h;
}
}
set_bnd ( N, 1, u );
set_bnd ( N, 2, v );
}
void AdvanceVelocity
(
int N,
float * u,
float * v,
float * u0,
float * v0,
float visc,
float dt
)
{
add_source ( N, u, u0, dt );
add_source ( N, v, v0, dt );
SWAP ( u0, u );
diffuse ( N, 1, u, u0, visc, dt );
SWAP ( v0, v );
diffuse ( N, 2, v, v0, visc, dt );
project ( N, u, v, u0, v0 );
SWAP ( u0, u );
SWAP ( v0, v );
advect ( N, 1, u, u0, u0, v0, dt );
advect ( N, 2, v, v0, u0, v0, dt );
project ( N, u, v, u0, v0 );
}
void AdvanceDensity
(
int N,
float * x,
float * x0,
float * u,
float * v,
float diff,
float dt
)
{
add_source ( N, x, x0, dt );
SWAP ( x0, x );
diffuse ( N, 0, x, x0, diff, dt );
SWAP ( x0, x );
advect ( N, 0, x, x0, u, v, dt );
}
void advect
(
int N,
int b,
float * d,
float * d0,
float * u,
float * v,
float dt
)
{
int i0, j0, i1, j1;
float x, y, s0, t0, s1, t1, dt0;
dt0 = dt * N;
for ( int i = 1; i <= N; i++ )
{
for ( int j = 1; j <= N; j++ )
{
x = i - dt0 * u[ IX(i,j) ];
y = j - dt0 * v[ IX(i,j) ];
if( x < 0.5f )
{
x = 0.5f;
}
if( x > N + 0.5f )
{
x = N + 0.5f;
}
i0 = (int)x;
i1 = i0 + 1;
if( y < 0.5f )
{
y = 0.5f;
}
if( y > N + 0.5f )
{
y = N + 0.5f;
}
j0 = (int)y;
j1 = j0 + 1;
s1 = x - i0;
s0 = 1 - s1;
t1 = y - j0;
t0 = 1 - t1;
d[ IX(i,j) ] = s0 * ( t0 * d0[ IX(i0,j0) ] +
t1 * d0[ IX(i0,j1) ] ) +
s1 * ( t0 * d0[ IX(i1,j0) ] +
t1 * d0[ IX(i1,j1) ] );
}
}
set_bnd( N, b, d );
}
{
//GetPreviousState( dens_prev, u_prev, v_prev );
//AdvanceVelocity( N, u, v, u_prev, v_prev, visc, dt );
//AdvanceDensity( N, dens, dens_prev, u, v, diff, dt );
//DrawFluid( N, dens );
}
void add_source( int N, float * x, float * s, float dt )
{
int size = ( N + 2 ) * ( N + 2 );
for( int i = 0; i < size; i++ )
{
x[ i ] += dt * s[ i ];
}
}
-= Out here in the fields, I fight for my meals =-
