wully616 / phaser-fluid Goto Github PK

float epsilon=2;

void add_vorocity(int N, float * u, float * v, float dt) {

//vort is just the curl of the velocity field
#define vort(i,j) (( -0.5*( v[IX(i+1,j)]-v[IX(i-1,j)] + u[IX(i,j-1)]-u[IX(i,j+1)] )*N ))
	
	int i, j;

	int size = (N+2)*(N+2);

	float *fx		= (float *) malloc ( size*sizeof(float) );
	float *fy		= (float *) malloc ( size*sizeof(float) );

	FOR_EACH_CELL
		if(i==1 || j==1 || i==N || j==N) continue;

		float dvx = 0.5*(vort(i+1,j)-vort(i-1,j));
		float dvy = 0.5*(vort(i,j+1)-vort(i,j-1));

		float mag=sqrt(dvx*dvx+dvy*dvy);

		//apply a force equal to epsilon * cross(N,vor)
		fx[IX(i,j)]=mag > smallf ? epsilon*dt*dvy*vort(i,j)/(mag*N) : 0;
		fy[IX(i,j)]=mag > smallf ? epsilon*dt*dvx*vort(i,j)/(mag*N) : 0;
	END_FOR

	set_bnd ( N, 0, fx ); set_bnd ( N, 0, fy );


	FOR_EACH_CELL
		if(i==1 || j==1 || i==N || j==N) continue;

		if(u[IX(i,j)]) u[IX(i,j)]+=fx[IX(i,j)];
		if(v[IX(i,j)]) v[IX(i,j)]-=fy[IX(i,j)];
	END_FOR

	set_bnd ( N, 1, u ); set_bnd ( N, 2, v );

free(fx);
free(fy);

#undef vort

for (int x = 0; x < m_w-1; x++) {
for (int y = 0; y < m_h-1; y++) {
int cell = Cell(x,y);
float force_x =  mp_p0[cell] - mp_p0[cell+1];
float force_y =  mp_p0[cell] - mp_p0[cell+m_w];
mp_xv1[cell]     +=  a * force_x;
mp_xv1[cell+1]   +=  a * force_x;
mp_yv1[cell]     +=  a * force_y;
mp_yv1[cell+m_w] +=  a * force_y;
}