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static const std::string COLLIDE_SHADER_CODE = R"(
#version 430
layout (local_size_x = 1, local_size_y = 1) in;
layout (std430, binding=1) buffer bufferCollide{ float collideCells[]; };
layout (std430, binding=2) buffer bufferStream{ float streamCells[]; };
layout (std430, binding=3) buffer bufferFluid{ float fluidCells[]; };
uniform uint nX;
uniform uint nY;
const uint q = 9;
const float omega = 0.6;
const float displayAmplifier = 50.;
float get(uint x, uint y, int i, int j) {
return collideCells[q*nX*y + q*x + (i+1)*3 + j+1];
}
void set(uint x, uint y, int i, int j, float v) {
collideCells[q*nX*y + q*x + (i+1)*3 + j+1] = v;
}
void setFluid(uint x, uint y, vec2 v, float d) {
fluidCells[3*nX*y + 3*x + 0] = float(x)-nX/2 + displayAmplifier*v.x;
fluidCells[3*nX*y + 3*x + 1] = float(y)-nY/2 + displayAmplifier*v.y;
fluidCells[3*nX*y + 3*x + 2] = d;
}
float density(uint x, uint y) {
return collideCells[q*nX*y + q*x + 0]
+ collideCells[q*nX*y + q*x + 1]
+ collideCells[q*nX*y + q*x + 2]
+ collideCells[q*nX*y + q*x + 3]
+ collideCells[q*nX*y + q*x + 4]
+ collideCells[q*nX*y + q*x + 5]
+ collideCells[q*nX*y + q*x + 6]
+ collideCells[q*nX*y + q*x + 7]
+ collideCells[q*nX*y + q*x + 8];
}
vec2 velocity(uint x, uint y, float d) {
return 1./d * vec2(
get(x,y, 1, 0) - get(x,y,-1, 0) + get(x,y, 1, 1) - get(x,y,-1,-1) + get(x,y, 1,-1) - get(x,y,-1,1),
get(x,y, 0, 1) - get(x,y, 0,-1) + get(x,y, 1, 1) - get(x,y,-1,-1) - get(x,y, 1,-1) + get(x,y,-1,1)
);
}
float w(int i, int j) {
if ( i == -1 ) {
if ( j != 0 ) {
return 1./36.;
} else {
return 1./9.;
}
} else if ( i == 0 ) {
if ( j != 0 ) {
return 1./9.;
} else {
return 4./9.;
}
} else {
if ( j != 0 ) {
return 1./36.;
} else {
return 1./9.;
}
}
}
float comp(int x, int y, vec2 v) {
return x*v.x + y*v.y;
}
float sq(float x) {
return x*x;
}
float norm(vec2 v) {
return sqrt(sq(v.x)+sq(v.y));
}
void main() {
const uint x = gl_GlobalInvocationID.x;
const uint y = gl_GlobalInvocationID.y;
const float d = density(x,y);
const vec2 v = velocity(x,y,d);
setFluid(x,y,v,d);
for ( int i = -1; i <= 1; ++i ) {
for ( int j = -1; j <= 1; ++j ) {
const float eq = w(i,j) * d * (1 + 3*comp(i,j,v) + 4.5*sq(comp(i,j,v)) - 1.5*sq(norm(v)));
set(x,y,i,j, get(x,y,i,j) + omega * (eq - get(x,y,i,j)));
}
}
}
)";
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