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Some improvements #37

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1790e74
rm commented out lines
BenWheatley Feb 1, 2024
2a6887b
rm half a line that I'm surprised isn't a error
BenWheatley Feb 1, 2024
eec013c
rm commented out lines
BenWheatley Feb 1, 2024
5836645
rm unused variable
BenWheatley Feb 1, 2024
5965e8b
add braces
BenWheatley Feb 1, 2024
6851849
add braces
BenWheatley Feb 1, 2024
a0f1b4e
cache out index
BenWheatley Feb 1, 2024
265a8d8
move invariants outside loops
BenWheatley Feb 1, 2024
2dbaf32
cache value
BenWheatley Feb 1, 2024
7710ceb
cache out index
BenWheatley Feb 1, 2024
22f44b9
move loop invariant
BenWheatley Feb 1, 2024
fc90883
rm unused function
BenWheatley Feb 1, 2024
9969e3a
rm var which is only incremented, never used
BenWheatley Feb 1, 2024
ef653d1
cache out index
BenWheatley Feb 1, 2024
5523a7a
cache out index
BenWheatley Feb 1, 2024
bb1587f
cache out index
BenWheatley Feb 1, 2024
2cd95ee
rm blank line
BenWheatley Feb 1, 2024
9d6ce8f
cache out index
BenWheatley Feb 1, 2024
d341ba8
cache out index
BenWheatley Feb 1, 2024
5e65a9a
rm unused var
BenWheatley Feb 1, 2024
7476294
rm whitespace
BenWheatley Feb 1, 2024
e38670a
rm whitespace
BenWheatley Feb 1, 2024
c04f492
rm whitespace
BenWheatley Feb 1, 2024
43a89f8
rm space before tab
BenWheatley Feb 1, 2024
e4fbd71
rm whitespace
BenWheatley Feb 1, 2024
ec777b5
move loop invariants, better names
BenWheatley Feb 1, 2024
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153 changes: 67 additions & 86 deletions tenMinutePhysics/17-fluidSim.html
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Original file line number Diff line number Diff line change
Expand Up @@ -77,8 +77,6 @@
var V_FIELD = 1;
var S_FIELD = 2;

var cnt = 0;

function cX(x) {
return x * cScale;
}
Expand All @@ -105,52 +103,51 @@
this.m = new Float32Array(this.numCells);
this.newM = new Float32Array(this.numCells);
this.m.fill(1.0)
var num = numX * numY;
}

integrate(dt, gravity) {
var n = this.numY;
for (var i = 1; i < this.numX; i++) {
for (var j = 1; j < this.numY-1; j++) {
if (this.s[i*n + j] != 0.0 && this.s[i*n + j-1] != 0.0)
this.v[i*n + j] += gravity * dt;
const index = i*n + j;
if (this.s[index] != 0.0 && this.s[index-1] != 0.0)
this.v[index] += gravity * dt;
}
}
}

solveIncompressibility(numIters, dt) {

var n = this.numY;
var cp = this.density * this.h / dt;

for (var iter = 0; iter < numIters; iter++) {

for (var i = 1; i < this.numX-1; i++) {
for (var j = 1; j < this.numY-1; j++) {

if (this.s[i*n + j] == 0.0)
const index = i*n + j;
if (this.s[index] == 0.0)
continue;

var s = this.s[i*n + j];
var sx0 = this.s[(i-1)*n + j];
var sx1 = this.s[(i+1)*n + j];
var sy0 = this.s[i*n + j-1];
var sy1 = this.s[i*n + j+1];
var s = this.s[index];
var sx0 = this.s[index-n];
var sx1 = this.s[index+n];
var sy0 = this.s[index-1];
var sy1 = this.s[index+1];
var s = sx0 + sx1 + sy0 + sy1;
if (s == 0.0)
continue;

var div = this.u[(i+1)*n + j] - this.u[i*n + j] +
this.v[i*n + j+1] - this.v[i*n + j];
var div = this.u[index+n] - this.u[index] +
this.v[index+1] - this.v[index];

var p = -div / s;
p *= scene.overRelaxation;
this.p[i*n + j] += cp * p;
this.p[index] += cp * p;

this.u[i*n + j] -= sx0 * p;
this.u[(i+1)*n + j] += sx1 * p;
this.v[i*n + j] -= sy0 * p;
this.v[i*n + j+1] += sy1 * p;
this.u[index] -= sx0 * p;
this.u[index+n] += sx1 * p;
this.v[index] -= sy0 * p;
this.v[index+1] += sy1 * p;
}
}
}
Expand Down Expand Up @@ -186,7 +183,6 @@
case U_FIELD: f = this.u; dy = h2; break;
case V_FIELD: f = this.v; dx = h2; break;
case S_FIELD: f = this.m; dx = h2; dy = h2; break

}

var x0 = Math.min(Math.floor((x-dx)*h1), this.numX-1);
Expand All @@ -210,21 +206,21 @@

avgU(i, j) {
var n = this.numY;
var u = (this.u[i*n + j-1] + this.u[i*n + j] +
this.u[(i+1)*n + j-1] + this.u[(i+1)*n + j]) * 0.25;
const index = i*n + j;
var u = (this.u[index-1] + this.u[index] +
this.u[index+n-1] + this.u[index+n]) * 0.25;
return u;

}

avgV(i, j) {
var n = this.numY;
var v = (this.v[(i-1)*n + j] + this.v[i*n + j] +
this.v[(i-1)*n + j+1] + this.v[i*n + j+1]) * 0.25;
const index = i*n + j;
var v = (this.v[index-n] + this.v[index] +
this.v[index-n+1] + this.v[index+1]) * 0.25;
return v;
}

advectVel(dt) {

this.newU.set(this.u);
this.newV.set(this.v);

Expand All @@ -234,60 +230,56 @@

for (var i = 1; i < this.numX; i++) {
for (var j = 1; j < this.numY; j++) {

cnt++;

const index = i*n + j;
// u component
if (this.s[i*n + j] != 0.0 && this.s[(i-1)*n + j] != 0.0 && j < this.numY - 1) {
if (this.s[index] != 0.0 && this.s[index-n] != 0.0 && j < this.numY - 1) {
var x = i*h;
var y = j*h + h2;
var u = this.u[i*n + j];
var u = this.u[index];
var v = this.avgV(i, j);
// var v = this.sampleField(x,y, V_FIELD);
x = x - dt*u;
y = y - dt*v;
u = this.sampleField(x,y, U_FIELD);
this.newU[i*n + j] = u;
this.newU[index] = u;
}
// v component
if (this.s[i*n + j] != 0.0 && this.s[i*n + j-1] != 0.0 && i < this.numX - 1) {
if (this.s[index] != 0.0 && this.s[index-1] != 0.0 && i < this.numX - 1) {
var x = i*h + h2;
var y = j*h;
var u = this.avgU(i, j);
// var u = this.sampleField(x,y, U_FIELD);
var v = this.v[i*n + j];
var v = this.v[index];
x = x - dt*u;
y = y - dt*v;
v = this.sampleField(x,y, V_FIELD);
this.newV[i*n + j] = v;
this.newV[index] = v;
}
}
}
}

this.u.set(this.newU);
this.v.set(this.newV);
}

advectSmoke(dt) {

this.newM.set(this.m);

var n = this.numY;
var h = this.h;
var h2 = 0.5 * h;
const scaleFactor = dt * 0.5;

for (var i = 1; i < this.numX-1; i++) {
for (var j = 1; j < this.numY-1; j++) {

if (this.s[i*n + j] != 0.0) {
var u = (this.u[i*n + j] + this.u[(i+1)*n + j]) * 0.5;
var v = (this.v[i*n + j] + this.v[i*n + j+1]) * 0.5;
var x = i*h + h2 - dt*u;
var y = j*h + h2 - dt*v;

this.newM[i*n + j] = this.sampleField(x,y, S_FIELD);
}
}
const index = i*n + j;
if (this.s[index] != 0.0) {
var du = (this.u[index] + this.u[index+n]) * scaleFactor;
var dv = (this.v[index] + this.v[index+1]) * scaleFactor;
var x = i*h + h2 - du;
var y = j*h + h2 - dv;

this.newM[index] = this.sampleField(x,y, S_FIELD);
}
}
}
this.m.set(this.newM);
}
Expand Down Expand Up @@ -339,11 +331,12 @@

var res = 100;

if (sceneNr == 0)
if (sceneNr == 0) {
res = 50;
else if (sceneNr == 3)
} else if (sceneNr == 3) {
res = 200;

}

var domainHeight = 1.0;
var domainWidth = domainHeight / simHeight * simWidth;
var h = domainHeight / res;
Expand All @@ -362,8 +355,9 @@
for (var i = 0; i < f.numX; i++) {
for (var j = 0; j < f.numY; j++) {
var s = 1.0; // fluid
if (i == 0 || i == f.numX-1 || j == 0)
if (i == 0 || i == f.numX-1 || j == 0) {
s = 0.0; // solid
}
f.s[i*n + j] = s
}
}
Expand All @@ -379,8 +373,9 @@
for (var i = 0; i < f.numX; i++) {
for (var j = 0; j < f.numY; j++) {
var s = 1.0; // fluid
if (i == 0 || j == 0 || j == f.numY-1)
if (i == 0 || j == 0 || j == f.numY-1) {
s = 0.0; // solid
}
f.s[i*n + j] = s

if (i == 1) {
Expand Down Expand Up @@ -433,17 +428,6 @@

// draw -------------------------------------------------------

function setColor(r,g,b) {
c.fillStyle = `rgb(
${Math.floor(255*r)},
${Math.floor(255*g)},
${Math.floor(255*b)})`
c.strokeStyle = `rgb(
${Math.floor(255*r)},
${Math.floor(255*g)},
${Math.floor(255*b)})`
}

function getSciColor(val, minVal, maxVal) {
val = Math.min(Math.max(val, minVal), maxVal- 0.0001);
var d = maxVal - minVal;
Expand Down Expand Up @@ -472,8 +456,9 @@
n = f.numY;

var cellScale = 1.1;

var h = f.h;
var cx = Math.floor(cScale * cellScale * h) + 1;
var cy = Math.floor(cScale * cellScale * h) + 1;

minP = f.p[0];
maxP = f.p[0];
Expand All @@ -488,11 +473,13 @@
var color = [255, 255, 255, 255]

for (var i = 0; i < f.numX; i++) {
var x = Math.floor(cX(i * h));
for (var j = 0; j < f.numY; j++) {

const index = i*n + j;
if (scene.showPressure) {
var p = f.p[i*n + j];
var s = f.m[i*n + j];
var p = f.p[index];
var s = f.m[index];
color = getSciColor(p, minP, maxP);
if (scene.showSmoke) {
color[0] = Math.max(0.0, color[0] - 255*s);
Expand All @@ -501,23 +488,20 @@
}
}
else if (scene.showSmoke) {
var s = f.m[i*n + j];
color[0] = 255*s;
color[1] = 255*s;
color[2] = 255*s;
var v = f.m[index] * 255;
color[0] = v;
color[1] = v;
color[2] = v;
if (scene.sceneNr == 2)
color = getSciColor(s, 0.0, 1.0);
}
else if (f.s[i*n + j] == 0.0) {
else if (f.s[index] == 0.0) {
color[0] = 0;
color[1] = 0;
color[2] = 0;
}

var x = Math.floor(cX(i * h));
var y = Math.floor(cY((j+1) * h));
var cx = Math.floor(cScale * cellScale * h) + 1;
var cy = Math.floor(cScale * cellScale * h) + 1;

r = color[0];
g = color[1];
Expand All @@ -544,14 +528,14 @@
scale = 0.02;

for (var i = 0; i < f.numX; i++) {
x0 = cX(i * h);
for (var j = 0; j < f.numY; j++) {

var u = f.u[i*n + j];
var v = f.v[i*n + j];
const index = i*n + j;
var u = f.u[index];
var v = f.v[index];

c.beginPath();

x0 = cX(i * h);
x1 = cX(i * h + u * scale);
y = cY((j + 0.5) * h );

Expand All @@ -574,7 +558,6 @@

if (scene.showStreamlines) {

var segLen = f.h * 0.2;
var numSegs = 15;

c.strokeStyle = "#000000";
Expand All @@ -592,8 +575,6 @@
var u = f.sampleField(x, y, U_FIELD);
var v = f.sampleField(x, y, V_FIELD);
l = Math.sqrt(u*u + v*v);
// x += u/l * segLen;
// y += v/l * segLen;
x += u * 0.01;
y += v * 0.01;
if (x > f.numX * f.h)
Expand All @@ -608,7 +589,6 @@

if (scene.showObstacle) {

c.strokeW
r = scene.obstacleRadius + f.h;
if (scene.showPressure)
c.fillStyle = "#000000";
Expand Down Expand Up @@ -760,9 +740,10 @@

function simulate()
{
if (!scene.paused)
if (!scene.paused) {
scene.fluid.simulate(scene.dt, scene.gravity, scene.numIters)
scene.frameNr++;
}
}

function update() {
Expand Down