多相流体力学模拟特效 - 守望者--AIR技术交流

/*
* 混相流 / Multiphase flow
*
* いくつかの種類の液体のシミュレーションです。
* クリックで注ぎます。
* Click:Pouring
*/
package {
import flash.utils.*;
import flash.text.*;
import flash.filters.*;
import flash.geom.*;
import flash.events.*;
import flash.display.*;
import net.hires.debug.Stats;
[SWF(frameRate = "60")]
public class Fluid extends Sprite {
public static const GRAVITY:Number = 0.05;//重力
public static const RANGE:Number = 16;//影響半径
public static const RANGE2:Number = RANGE * RANGE;//影響半径の二乗
public static const DENSITY:Number = 2.5;//流体の基準(安定する)密度
public static const PRESSURE:Number = 1;//圧力係数
public static const PRESSURE_NEAR:Number = 1;//近距離圧力係数
public static const VISCOSITY:Number = 0.1;//粘性係数
public static const NUM_GRIDS:int = 29;//グリッド数(≒ 465 / RANGE)
public static const INV_GRID_SIZE:Number = 1 / (465 / NUM_GRIDS);//グリッドサイズの逆数(≒ 1 / RANGE)
private var particles:Vector.<Particle>;
private var numParticles:uint;
private var neighbors:Vector.<Neighbor>;
private var numNeighbors:uint;
private var count:int;
private var press:Boolean;
private var bitmap:BitmapData;
private var grids:Vector.<Vector.<Grid>>;
private const COLOR_TRANSFORM:ColorTransform = new ColorTransform(0.5, 0.5, 0.5);
public function Fluid() {
initialize();
}
private function initialize():void {
particles = new Vector.<Particle>();
numParticles = 0;
neighbors = new Vector.<Neighbor>();
numNeighbors = 0;
grids = new Vector.<Vector.<Grid>>(NUM_GRIDS, true);
for(var i:int = 0; i < NUM_GRIDS; i++) {
grids[i] = new Vector.<Grid>(NUM_GRIDS, true);
for(var j:int = 0; j < NUM_GRIDS; j++)
grids[i][j] = new Grid();
}
count = 0;
bitmap = new BitmapData(465, 465, false, 0);
addChild(new Bitmap(bitmap));
// var s:Stats = new Stats();
// s.alpha = 0.8;
// addChild(s);
addEventListener(Event.ENTER_FRAME, frame);
stage.addEventListener(MouseEvent.MOUSE_DOWN, function(e:MouseEvent):void {press = true;});
stage.addEventListener(MouseEvent.MOUSE_UP, function(e:MouseEvent):void {press = false;});
}
private function frame(e:Event):void {
if(press)
pour();
move();
}
private function pour():void {
for(var i:int = -4; i <= 4; i++) {
particles[numParticles++] = new Particle(mouseX + i * 10, mouseY,
count / 10 % 5);
particles[numParticles - 1].vy = 5;
}
}
private function move():void {
count++;
updateGrids();
findNeighbors();
calcForce();
bitmap.lock();
bitmap.colorTransform(bitmap.rect, COLOR_TRANSFORM);
for(var i:uint = 0; i < numParticles; i++) {
const p:Particle = particles[i];
p.move();
bitmap.fillRect(new Rectangle(p.x - 1, p.y - 1, 3, 3), p.color);
}
bitmap.unlock();
}
private function updateGrids():void {
var i:uint;
var j:uint;
for(i = 0; i < NUM_GRIDS; i++)
for(j = 0; j < NUM_GRIDS; j++)
grids[i][j].numParticles = 0;
for(i = 0; i < numParticles; i++) {
const p:Particle = particles[i];
p.fx = p.fy = p.density = p.densityNear = 0;
p.gx = p.x * INV_GRID_SIZE; // グリッドのどこにいるか計算
p.gy = p.y * INV_GRID_SIZE;
if(p.gx < 0) // グリッドから外れてたら一番近いとこに入ってることにする
p.gx = 0;
if(p.gy < 0)
p.gy = 0;
if(p.gx > NUM_GRIDS - 1)
p.gx = NUM_GRIDS - 1;
if(p.gy > NUM_GRIDS - 1)
p.gy = NUM_GRIDS - 1;
}
}
private function findNeighbors():void { // 空間分割で近接粒子を計算
numNeighbors = 0;
for(var i:uint = 0; i < numParticles; i++) {
const p:Particle = particles[i];
const xMin:Boolean = p.gx != 0;
const xMax:Boolean = p.gx != NUM_GRIDS - 1;
const yMin:Boolean = p.gy != 0;
const yMax:Boolean = p.gy != NUM_GRIDS - 1;
findNeighborsInGrid(p, grids[p.gx][p.gy]);
if(xMin) findNeighborsInGrid(p, grids[p.gx - 1][p.gy]);
if(xMax) findNeighborsInGrid(p, grids[p.gx + 1][p.gy]);
if(yMin) findNeighborsInGrid(p, grids[p.gx][p.gy - 1]);
if(yMax) findNeighborsInGrid(p, grids[p.gx][p.gy + 1]);
if(xMin && yMin) findNeighborsInGrid(p, grids[p.gx - 1][p.gy - 1]);
if(xMin && yMax) findNeighborsInGrid(p, grids[p.gx - 1][p.gy + 1]);
if(xMax && yMin) findNeighborsInGrid(p, grids[p.gx + 1][p.gy - 1]);
if(xMax && yMax) findNeighborsInGrid(p, grids[p.gx + 1][p.gy + 1]);
grids[p.gx][p.gy].add(p);
}
}
private function findNeighborsInGrid(pi:Particle, g:Grid):void {
for(var j:uint = 0; j < g.numParticles; j++) {
var pj:Particle = g.particles[j];
const distance:Number = (pi.x - pj.x) * (pi.x - pj.x) + (pi.y - pj.y) * (pi.y - pj.y);
if(distance < RANGE2) {
if(neighbors.length == numNeighbors)
neighbors[numNeighbors] = new Neighbor();
neighbors[numNeighbors++].setParticle(pi, pj);
}
}
}
private function calcForce():void {
for(var i:uint = 0; i < numNeighbors; i++)
neighbors[i].calcForce();
}
}
}
class Particle {
public var x:Number;
public var y:Number;
public var gx:int;
public var gy:int;
public var vx:Number;
public var vy:Number;
public var fx:Number;
public var fy:Number;
public var density:Number;
public var densityNear:Number;
public var color:int;
public var type:int;
public const GRAVITY:Number = Fluid.GRAVITY;
public function Particle(x:Number, y:Number, type:int) {
this.x = x;
this.y = y
this.type = type;
vx = vy = fx = fy = 0;
switch(type) {
case 0:
color = 0x6060ff;
break;
case 1:
color = 0xff6000;
break;
case 2:
color = 0xff0060;
break;
case 3:
color = 0x00d060;
break;
case 4:
color = 0xd0d000;
break;
}
}
public function move():void {
vy += GRAVITY;
if(density > 0) {
vx += fx / (density * 0.9 + 0.1); // 本当は密度で割る計算だけど0に近かった時に
vy += fy / (density * 0.9 + 0.1); // 粒子が飛び出すから微調整
}
x += vx;
y += vy;
if(x < 5) // 壁境界
vx += (5 - x) * 0.5 - vx * 0.5;
if(x > 460)
vx += (460 - x) * 0.5 - vx * 0.5;
if(y < 5)
vy += (5 - y) * 0.5 - vy * 0.5;
if(y > 460)
vy += (460 - y) * 0.5 - vy * 0.5;
}
}
class Neighbor {
public var p1:Particle;
public var p2:Particle;
public var distance:Number;
public var nx:Number;
public var ny:Number;
public var weight:Number;
public const RANGE:Number = Fluid.RANGE;
public const PRESSURE:Number = Fluid.PRESSURE;
public const PRESSURE_NEAR:Number = Fluid.PRESSURE_NEAR;
public const DENSITY:Number = Fluid.DENSITY;
public const VISCOSITY:Number = Fluid.VISCOSITY;
public function Neighbor() {
}
public function setParticle(p1:Particle, p2:Particle):void { // 使いまわし
this.distance = distance;
this.p1 = p1;
this.p2 = p2;
nx = p1.x - p2.x;
ny = p1.y - p2.y;
distance = Math.sqrt(nx * nx + ny * ny);
weight = 1 - distance / RANGE;
var density:Number = weight * weight; // 普通の圧力カーネルは距離の二乗
p1.density += density;
p2.density += density;
density *= weight * PRESSURE_NEAR; // 粒子が近づきすぎないよう近距離用のカーネルを計算
p1.densityNear += density;
p2.densityNear += density;
const invDistance:Number = 1 / distance;
nx *= invDistance;
ny *= invDistance;
}
public function calcForce():void {
var p:Number;
if(p1.type != p2.type) // 違うタイプの粒子なら安定する密度をちょっと減らす
p = (p1.density + p2.density - DENSITY * 1.5) * PRESSURE;
else // 同じタイプなら普通に計算
p = (p1.density + p2.density - DENSITY * 2) * PRESSURE;
const pn:Number = (p1.densityNear + p2.densityNear) * PRESSURE_NEAR; // 基準密度に関係なく近づきすぎたら跳ね返す！
var pressureWeight:Number = weight * (p + weight * pn); // 結果としてかかる圧力
var viscosityWeight:Number = weight * VISCOSITY;
var fx:Number = nx * pressureWeight;
var fy:Number = ny * pressureWeight;
fx += (p2.vx - p1.vx) * viscosityWeight; // 単純に粘性項を解く
fy += (p2.vy - p1.vy) * viscosityWeight;
p1.fx += fx;
p1.fy += fy;
p2.fx -= fx;
p2.fy -= fy;
}
}
class Grid {
public var particles:Vector.<Particle>;
public var numParticles:uint;
public function Grid() {
particles = new Vector.<Particle>;
}
public function add(p:Particle):void {
particles[numParticles++] = p;
}
}

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