There is an bug in your code : once you make the stage width and height different, the code will crash. (works : 465 x 465, 800 x 800, 1200 x 1200 | don't work : 200 x 400, 600 x 800).
/**
* Copyright mtok ( http://wonderfl.net/user/mtok )
* MIT License ( http://www.opensource.org/licenses/mit-license.php )
* Downloaded from: http://wonderfl.net/c/rYH7
*/
package
{
import flash.display.Graphics;
import flash.display.Sprite;
import flash.events.Event;
import flash.filters.GlowFilter;
import net.hires.debug.Stats;
/**
* AdvancED Actionscript 3
* Advanced Collision Detectionより
*
* grid- based collision detection
*
* @author Motoki Matsumoto
*/
public class GridBaseCollisionDetection extends Sprite
{
private var _numBallFixed:uint = 100;
private var _numBall:uint = 100;
private var _background:Sprite;
private var _circles:Vector.<Circle>;
private var _dt:Number;
private var _grid:Grid;
private var _gridSize:Number = 30;
private var _screen:Sprite;
public function GridBaseCollisionDetection()
{
addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);
}
private function addedToStageHandler(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);
init();
}
private function init():void {
addChild(_background = new Sprite());
drawGrid(50);
_dt = 1 / stage.frameRate;
addChild(_screen = new Sprite());
makeCircles();
_grid = new Grid(stage.stageWidth, stage.stageHeight, _gridSize);
addChild(new Stats());
addEventListener(Event.ENTER_FRAME, enterFrameHandler);
}
private function makeCircles():void
{
var w:Number = stage.stageWidth;
var h:Number = stage.stageHeight;
var c:Circle;
var i:int;
_circles = new Vector.<Circle>();
for (i = 0; i < _numBallFixed; i++) {
c = new Circle(6);
_circles.push(c);
c.displayObj = new Ball(c.r, 0x00ff55);
c.x = c.displayObj.x = w * Math.random();
c.y = c.displayObj.y = h * Math.random();
c.fixed = true;
addChild(c.displayObj);
}
for (i = 0; i < _numBall; i++) {
c = new Circle(2);
_circles.push(c);
c.displayObj = new Ball(c.r, 0xff5500);
c.x = c.displayObj.x = w * Math.random();
c.y = c.displayObj.y = h * Math.random();
addChild(c.displayObj);
}
}
private function enterFrameHandler(e:Event):void
{
var len:int = _circles.length;
var c:Circle;
for (var i:int = 0; i < len; i++) {
c = _circles[i] as Circle;
c.step(_dt);
c.accelerate(0, 0.09);
c.displayObj.x = c.x;
c.displayObj.y = c.y;
if (c.y > stage.stageHeight) {
c.y = 0;
c.vx = 0;
c.vy = 0;
}
}
var vecCol:Vector.<Collision>;
var col:Collision;
/*-----------------------------------
* collisionCheckAを使うと、総当たりで衝突判定
* collisionCheckBを使うと、グリッドを使った衝突判定を行います。
* 比較したい場合は書き換えてください。
-----------------------------------*/
//vecCol = collisionCheckA();
vecCol = collisionCheckB();
showCollisions(vecCol);
}
private function showCollisions(collisions:Vector.<Collision>):void
{
var len:int = collisions.length;
var col:Collision;
var i:int;
_screen.graphics.clear();
for (i = 0; i < len; i++) {
col = collisions[i];
_screen.graphics.beginFill(0x0000ff);
_screen.graphics.drawCircle(col.c1.x, col.c1.y, col.c1.r+2);
_screen.graphics.endFill();
_screen.graphics.beginFill(0x0000ff);
_screen.graphics.drawCircle(col.c2.x, col.c2.y, col.c2.r+2);
_screen.graphics.endFill();
}
}
/*
* グリッドベースの衝突チェック
*/
private function collisionCheckB():Vector.<Collision>
{
return _grid.check(_circles);
}
/*
* 総当たり衝突チェック
*/
private function collisionCheckA():Vector.<Collision>
{
var i:int = 0, j:int = 0;
var len:int = _circles.length;
var c1:Circle, c2:Circle;
var collisions:Vector.<Collision> = new Vector.<Collision>();
for (i = 0; i < len; i++) {
c1 = _circles[i];
for (j = i+1; j < len; j++) {
c2 = _circles[j];
if (c1.hitTest(c2)) {
collisions.push(new Collision(c1, c2));
}
}
}
return collisions;
}
private function drawGrid(span:Number):void {
var g:Graphics = _background.graphics;
if (span < 0) {
return ;
}
g.clear();
g.lineStyle(1, 0xccccff);
var w:Number = stage.stageWidth;
var h:Number = stage.stageHeight;
var n:Number;
n = 0;
while (n < h) {
g.moveTo(0, n);
g.lineTo(w, n);
n += span;
}
n = 0;
while (n < w) {
g.moveTo(n, 0);
g.lineTo(n, h);
n += span;
}
}
}
}
import flash.display.DisplayObject;
import flash.display.Graphics;
import flash.display.Sprite;
class Ball extends Sprite {
private var _r:Number;
private var _color:uint;
public function Ball(r:Number = 10, color:uint = 0xcccccc):void {
_r = r;
_color = color;
_draw();
}
private function _draw():void
{
var g:Graphics = this.graphics;
g.clear();
g.beginFill(_color);
g.drawCircle(0, 0, _r);
g.endFill();
}
public function get r():Number { return _r; }
public function set r(value:Number):void
{
_r = value;
_draw();
}
public function get color():uint { return _color; }
public function set color(value:uint):void
{
_color = value;
_draw();
}
}
class Collision {
public var c1:Circle;
public var c2:Circle;
public function Collision(c1:Circle, c2:Circle) {
this.c1 = c1;
this.c2 = c2;
}
}
class Circle {
public var x:Number = 0;
public var y:Number = 0;
public var vx:Number = 0;
public var vy:Number = 0;
public var r:Number;
public var friction:Number = 1;
private var _fixed:Boolean;
public var displayObj:DisplayObject;
public function Circle(r:Number) {
this.r = r;
}
public function hitTest(b:Circle):Boolean {
if (b == this) return false;
var dx:Number = x - b.x;
var dy:Number = y - b.y;
var d:Number = Math.sqrt(dx * dx + dy * dy);
if ((b.r + r ) > d) {
return true;
}
return false;
}
public function accelerate(ax:Number, ay:Number):void {
if (_fixed) return;
vx += ax;
vy += ay;
}
public function step(t:Number):void {
if (_fixed) return;
x += vx * t;
y += vy * t;
vx *= friction;
vy *= friction;
}
public function get fixed():Boolean { return _fixed; }
public function set fixed(value:Boolean):void
{
_fixed = value;
if (_fixed) {
vx = 0;
vy = 0;
}
}
}
class Grid {
private var _grid:Vector.<Vector.<Circle>>;
private var _size:Number;
private var _gridLen:int;
private var _cols:int;
private var _rows:int;
private var _collisions:Vector.<Collision>;
public function Grid(width:Number, height:Number, size:Number) {
_size = size;
_cols = Math.ceil(width / size);
_rows = Math.ceil(height / size);
_gridLen = _cols * _rows;
}
public function check(circles:Vector.<Circle>):Vector.<Collision> {
_grid = new Vector.<Vector.<Circle>>(_gridLen);
_assign(circles);
return _check();
}
private function _assign(circles:Vector.<Circle>):void {
var c:Circle;
var len:int = circles.length;
var col:int, row:int;
var vec:Vector.<Circle>;
for (var i:int = 0; i < len; i++) {
c = circles[i];
col = Math.floor(c.x / _size);
row = Math.floor(c.y / _size);
if ( col >= _cols || row >= _rows) {
//範囲外
}else {
vec = _grid[_cols * row + col];
if (vec == null) {
vec = _grid[_cols * row + col] = new Vector.<Circle>();
}
vec.push(c);
}
}
}
private function _check():Vector.<Collision> {
var i:int, j:int;
_collisions = new Vector.<Collision>();
for (i = 0; i < _rows; i++) {
for (j = 0; j < _cols; j++) {
_checkSingleCell(j, i);
_checkTwoCell(j, i, j+1, i);
_checkTwoCell(j, i, j-1, i+1);
_checkTwoCell(j, i, j, i+1);
_checkTwoCell(j, i, j+1, i+1);
}
}
return _collisions;
}
private function _checkSingleCell(col:int, row:int):void {
var c:Vector.<Circle> = _grid[_cols * row + col];
if (c == null) return;
var len:int = c.length;
var i:int, j:int;
var c1:Circle, c2:Circle;
for (i = 0; i < len; i++) {
c1 = c[i];
for (j = i + 1; j < len; j++) {
c2 = c[j];
if (c1.hitTest(c2)) {
_collisions.push(new Collision(c1, c2));
}
}
}
}
private function _checkTwoCell(col1:int, row1:int, col2:int, row2:int):void{
if (col2 < 0 || col2 >= _rows || row2 >= _cols) return;
var vec1:Vector.<Circle> = _grid[_cols * row1 + col1];
var vec2:Vector.<Circle> = _grid[_cols * row2 + col2];
if (vec1 == null || vec2 == null) return;
var len1:int = vec1.length;
var len2:int = vec2.length;
var c1:Circle, c2:Circle;
var i:int, j:int;
for (i = 0; i < len1; i++) {
c1 = vec1[i];
for (j = 0; j < len2; j++) {
c2 = vec2[j];
if (c1.hitTest(c2)) {
_collisions.push(new Collision(c1,c2));
}
}
}
}
public function get size():Number { return _size; }
public function set size(value:Number):void
{
_size = value;
}
}