tor-browser

navier-stokes.js (13431B)

---

/**
* Copyright 2013 the V8 project authors. All rights reserved.
* Copyright 2009 Oliver Hunt <http://nerget.com>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Update 10/21/2013: fixed loop variables at line 119
*/

var NavierStokes = new BenchmarkSuite('NavierStokes', [1484000],
                                     [new Benchmark('NavierStokes',
                                                    true,
                                                    false,
                                                    180,
                                                    runNavierStokes,
                                                    setupNavierStokes,
                                                    tearDownNavierStokes,
                                                    null,
                                                    16)]);

var solver = null;
var nsFrameCounter = 0;

function runNavierStokes()
{
   solver.update();
   nsFrameCounter++;

   if(nsFrameCounter==15)
       checkResult(solver.getDens());
}

function checkResult(dens) {

   this.result = 0;
   for (var i=7000;i<7100;i++) {
       this.result+=~~((dens[i]*10));
   }

   if (this.result!=77) {
       throw(new Error("checksum failed"));
   }
}

function setupNavierStokes()
{
   solver = new FluidField(null);
   solver.setResolution(128, 128);
   solver.setIterations(20);
   solver.setDisplayFunction(function(){});
   solver.setUICallback(prepareFrame);
   solver.reset();
}

function tearDownNavierStokes()
{
   solver = null;
}

function addPoints(field) {
   var n = 64;
   for (var i = 1; i <= n; i++) {
       field.setVelocity(i, i, n, n);
       field.setDensity(i, i, 5);
       field.setVelocity(i, n - i, -n, -n);
       field.setDensity(i, n - i, 20);
       field.setVelocity(128 - i, n + i, -n, -n);
       field.setDensity(128 - i, n + i, 30);
   }
}

var framesTillAddingPoints = 0;
var framesBetweenAddingPoints = 5;

function prepareFrame(field)
{
   if (framesTillAddingPoints == 0) {
       addPoints(field);
       framesTillAddingPoints = framesBetweenAddingPoints;
       framesBetweenAddingPoints++;
   } else {
       framesTillAddingPoints--;
   }
}

// Code from Oliver Hunt (http://nerget.com/fluidSim/pressure.js) starts here.
function FluidField(canvas) {
   function addFields(x, s, dt)
   {
       for (var i=0; i<size ; i++ ) x[i] += dt*s[i];
   }

   function set_bnd(b, x)
   {
       if (b===1) {
           for (var i = 1; i <= width; i++) {
               x[i] =  x[i + rowSize];
               x[i + (height+1) *rowSize] = x[i + height * rowSize];
           }

           for (var j = 1; j <= height; j++) {
               x[j * rowSize] = -x[1 + j * rowSize];
               x[(width + 1) + j * rowSize] = -x[width + j * rowSize];
           }
       } else if (b === 2) {
           for (var i = 1; i <= width; i++) {
               x[i] = -x[i + rowSize];
               x[i + (height + 1) * rowSize] = -x[i + height * rowSize];
           }

           for (var j = 1; j <= height; j++) {
               x[j * rowSize] =  x[1 + j * rowSize];
               x[(width + 1) + j * rowSize] =  x[width + j * rowSize];
           }
       } else {
           for (var i = 1; i <= width; i++) {
               x[i] =  x[i + rowSize];
               x[i + (height + 1) * rowSize] = x[i + height * rowSize];
           }

           for (var j = 1; j <= height; j++) {
               x[j * rowSize] =  x[1 + j * rowSize];
               x[(width + 1) + j * rowSize] =  x[width + j * rowSize];
           }
       }
       var maxEdge = (height + 1) * rowSize;
       x[0]                 = 0.5 * (x[1] + x[rowSize]);
       x[maxEdge]           = 0.5 * (x[1 + maxEdge] + x[height * rowSize]);
       x[(width+1)]         = 0.5 * (x[width] + x[(width + 1) + rowSize]);
       x[(width+1)+maxEdge] = 0.5 * (x[width + maxEdge] + x[(width + 1) + height * rowSize]);
   }

   function lin_solve(b, x, x0, a, c)
   {
       if (a === 0 && c === 1) {
           for (var j=1 ; j<=height; j++) {
               var currentRow = j * rowSize;
               ++currentRow;
               for (var i = 0; i < width; i++) {
                   x[currentRow] = x0[currentRow];
                   ++currentRow;
               }
           }
           set_bnd(b, x);
       } else {
           var invC = 1 / c;
           for (var k=0 ; k<iterations; k++) {
               for (var j=1 ; j<=height; j++) {
                   var lastRow = (j - 1) * rowSize;
                   var currentRow = j * rowSize;
                   var nextRow = (j + 1) * rowSize;
                   var lastX = x[currentRow];
                   ++currentRow;
                   for (var i=1; i<=width; i++)
                       lastX = x[currentRow] = (x0[currentRow] + a*(lastX+x[++currentRow]+x[++lastRow]+x[++nextRow])) * invC;
               }
               set_bnd(b, x);
           }
       }
   }

   function diffuse(b, x, x0, dt)
   {
       var a = 0;
       lin_solve(b, x, x0, a, 1 + 4*a);
   }

   function lin_solve2(x, x0, y, y0, a, c)
   {
       if (a === 0 && c === 1) {
           for (var j=1 ; j <= height; j++) {
               var currentRow = j * rowSize;
               ++currentRow;
               for (var i = 0; i < width; i++) {
                   x[currentRow] = x0[currentRow];
                   y[currentRow] = y0[currentRow];
                   ++currentRow;
               }
           }
           set_bnd(1, x);
           set_bnd(2, y);
       } else {
           var invC = 1/c;
           for (var k=0 ; k<iterations; k++) {
               for (var j=1 ; j <= height; j++) {
                   var lastRow = (j - 1) * rowSize;
                   var currentRow = j * rowSize;
                   var nextRow = (j + 1) * rowSize;
                   var lastX = x[currentRow];
                   var lastY = y[currentRow];
                   ++currentRow;
                   for (var i = 1; i <= width; i++) {
                       lastX = x[currentRow] = (x0[currentRow] + a * (lastX + x[currentRow] + x[lastRow] + x[nextRow])) * invC;
                       lastY = y[currentRow] = (y0[currentRow] + a * (lastY + y[++currentRow] + y[++lastRow] + y[++nextRow])) * invC;
                   }
               }
               set_bnd(1, x);
               set_bnd(2, y);
           }
       }
   }

   function diffuse2(x, x0, y, y0, dt)
   {
       var a = 0;
       lin_solve2(x, x0, y, y0, a, 1 + 4 * a);
   }

   function advect(b, d, d0, u, v, dt)
   {
       var Wdt0 = dt * width;
       var Hdt0 = dt * height;
       var Wp5 = width + 0.5;
       var Hp5 = height + 0.5;
       for (var j = 1; j<= height; j++) {
           var pos = j * rowSize;
           for (var i = 1; i <= width; i++) {
               var x = i - Wdt0 * u[++pos];
               var y = j - Hdt0 * v[pos];
               if (x < 0.5)
                   x = 0.5;
               else if (x > Wp5)
                   x = Wp5;
               var i0 = x | 0;
               var i1 = i0 + 1;
               if (y < 0.5)
                   y = 0.5;
               else if (y > Hp5)
                   y = Hp5;
               var j0 = y | 0;
               var j1 = j0 + 1;
               var s1 = x - i0;
               var s0 = 1 - s1;
               var t1 = y - j0;
               var t0 = 1 - t1;
               var row1 = j0 * rowSize;
               var row2 = j1 * rowSize;
               d[pos] = s0 * (t0 * d0[i0 + row1] + t1 * d0[i0 + row2]) + s1 * (t0 * d0[i1 + row1] + t1 * d0[i1 + row2]);
           }
       }
       set_bnd(b, d);
   }

   function project(u, v, p, div)
   {
       var h = -0.5 / Math.sqrt(width * height);
       for (var j = 1 ; j <= height; j++ ) {
           var row = j * rowSize;
           var previousRow = (j - 1) * rowSize;
           var prevValue = row - 1;
           var currentRow = row;
           var nextValue = row + 1;
           var nextRow = (j + 1) * rowSize;
           for (var i = 1; i <= width; i++ ) {
               div[++currentRow] = h * (u[++nextValue] - u[++prevValue] + v[++nextRow] - v[++previousRow]);
               p[currentRow] = 0;
           }
       }
       set_bnd(0, div);
       set_bnd(0, p);

       lin_solve(0, p, div, 1, 4 );
       var wScale = 0.5 * width;
       var hScale = 0.5 * height;
       for (var j = 1; j<= height; j++ ) {
           var prevPos = j * rowSize - 1;
           var currentPos = j * rowSize;
           var nextPos = j * rowSize + 1;
           var prevRow = (j - 1) * rowSize;
           var currentRow = j * rowSize;
           var nextRow = (j + 1) * rowSize;

           for (var i = 1; i<= width; i++) {
               u[++currentPos] -= wScale * (p[++nextPos] - p[++prevPos]);
               v[currentPos]   -= hScale * (p[++nextRow] - p[++prevRow]);
           }
       }
       set_bnd(1, u);
       set_bnd(2, v);
   }

   function dens_step(x, x0, u, v, dt)
   {
       addFields(x, x0, dt);
       diffuse(0, x0, x, dt );
       advect(0, x, x0, u, v, dt );
   }

   function vel_step(u, v, u0, v0, dt)
   {
       addFields(u, u0, dt );
       addFields(v, v0, dt );
       var temp = u0; u0 = u; u = temp;
       var temp = v0; v0 = v; v = temp;
       diffuse2(u,u0,v,v0, dt);
       project(u, v, u0, v0);
       var temp = u0; u0 = u; u = temp;
       var temp = v0; v0 = v; v = temp;
       advect(1, u, u0, u0, v0, dt);
       advect(2, v, v0, u0, v0, dt);
       project(u, v, u0, v0 );
   }
   var uiCallback = function(d,u,v) {};

   function Field(dens, u, v) {
       // Just exposing the fields here rather than using accessors is a measurable win during display (maybe 5%)
       // but makes the code ugly.
       this.setDensity = function(x, y, d) {
            dens[(x + 1) + (y + 1) * rowSize] = d;
       }
       this.getDensity = function(x, y) {
            return dens[(x + 1) + (y + 1) * rowSize];
       }
       this.setVelocity = function(x, y, xv, yv) {
            u[(x + 1) + (y + 1) * rowSize] = xv;
            v[(x + 1) + (y + 1) * rowSize] = yv;
       }
       this.getXVelocity = function(x, y) {
            return u[(x + 1) + (y + 1) * rowSize];
       }
       this.getYVelocity = function(x, y) {
            return v[(x + 1) + (y + 1) * rowSize];
       }
       this.width = function() { return width; }
       this.height = function() { return height; }
   }
   function queryUI(d, u, v)
   {
       for (var i = 0; i < size; i++)
           u[i] = v[i] = d[i] = 0.0;
       uiCallback(new Field(d, u, v));
   }

   this.update = function () {
       queryUI(dens_prev, u_prev, v_prev);
       vel_step(u, v, u_prev, v_prev, dt);
       dens_step(dens, dens_prev, u, v, dt);
       displayFunc(new Field(dens, u, v));
   }
   this.setDisplayFunction = function(func) {
       displayFunc = func;
   }

   this.iterations = function() { return iterations; }
   this.setIterations = function(iters) {
       if (iters > 0 && iters <= 100)
          iterations = iters;
   }
   this.setUICallback = function(callback) {
       uiCallback = callback;
   }
   var iterations = 10;
   var visc = 0.5;
   var dt = 0.1;
   var dens;
   var dens_prev;
   var u;
   var u_prev;
   var v;
   var v_prev;
   var width;
   var height;
   var rowSize;
   var size;
   var displayFunc;
   function reset()
   {
       rowSize = width + 2;
       size = (width+2)*(height+2);
       dens = new Array(size);
       dens_prev = new Array(size);
       u = new Array(size);
       u_prev = new Array(size);
       v = new Array(size);
       v_prev = new Array(size);
       for (var i = 0; i < size; i++)
           dens_prev[i] = u_prev[i] = v_prev[i] = dens[i] = u[i] = v[i] = 0;
   }
   this.reset = reset;
   this.getDens = function()
   {
       return dens;
   }
   this.setResolution = function (hRes, wRes)
   {
       var res = wRes * hRes;
       if (res > 0 && res < 1000000 && (wRes != width || hRes != height)) {
           width = wRes;
           height = hRes;
           reset();
           return true;
       }
       return false;
   }
   this.setResolution(64, 64);
}