基于Voronoi的粒子特效 - 守望者--AIR技术交流

/**
* Sketch of Voronoi
* I will recommend seeing in "FULL SCREEN" mode.
* http://alumican.net/#/c/cells
*
* based on 超速ボロノイ図 by fumix
* @see http://wonderfl.net/c/3TKq/
*
* Fortune's algorithm - Wikipedia, the free encyclopedia
* @see http://en.wikipedia.org/wiki/Fortune's_algorithm
*
* Controul > Speedy Voronoi diagrams in as3/flash
* @see http://blog.controul.com/2009/05/speedy-voronoi-diagrams-in-as3flash/
*
* @author Yukiya Okuda<alumican.net>
*/
package
{
import com.flashdynamix.utils.SWFProfiler;
import flash.display.Graphics;
import flash.display.Shape;
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageQuality;
import flash.display.StageScaleMode;
import flash.events.Event;
public class Main extends Sprite
{
private const N:int = 700;
private const PI:Number = Math.PI;
private const PI2:Number = PI * 2;
private const TO_DEGREE:Number = 180 / PI;
private const TO_RADIAN:Number = PI / 180;
private var _fortune:Fortune;
private var _points:Vector.<Number2>;
private var _pointCount:int;
private var _first:Number2;
private var _oldMouseX:Number;
private var _oldMouseY:Number;
private var _background:Shape;
private var _canvas:Shape;
private var _range:Number;
public function Main():void
{
Wonderfl.disable_capture();
addEventListener(Event.ADDED_TO_STAGE, _init);
}
private function _init(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, _init);
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.quality = StageQuality.MEDIUM;
stage.frameRate = 60;
var sw:Number = stage.stageWidth,
sh:Number = stage.stageHeight;
_fortune = new Fortune();
_background = addChild( new Shape() ) as Shape;
_background.graphics.beginFill(0x0);
_background.graphics.drawRect(0, 0, sw, sh);
_background.graphics.endFill();
_canvas = addChild( new Shape() ) as Shape;
_points = new Vector.<Number2>(N);
var p:Number2;
var old:Number2;
for (var i:int = 0; i < N; ++i)
{
_points[i] = p = new Number2();
if (_first == null)
{
old = _first = p;
}
else
{
old.next = p;
old = p;
}
}
_oldMouseX = mouseX;
_oldMouseY = mouseY;
addEventListener(Event.ENTER_FRAME, _update);
stage.addEventListener(Event.RESIZE, _resize);
_resize(null);
SWFProfiler.init(this);
}
private function _resize(e:Event):void
{
var sw:Number = stage.stageWidth,
sh:Number = stage.stageHeight;
_background.width = sw;
_background.height = sh;
_range = 100 * (Math.min(sw, sh) / 465);
var p:Number2 = _first;
do
{
var px:Number = p.x = Math.random() * sw;
var py:Number = p.y = Math.random() * sh;
var angle:Number = Math.atan2(py - sh * 0.5, px - sw * 0.5);
p.defaultVx = p.vx = 0.3 * Math.cos(angle);
p.defaultVy = p.vy = 0.3 * Math.sin(angle);
}
while (p = p.next);
}
private function _update(e:Event):void
{
_interaction();
_draw();
}
private function _interaction():void
{
var sw:Number = stage.stageWidth,
sh:Number = stage.stageHeight,
cx:Number = sw * 0.5,
cy:Number = sh * 0.5,
mx:Number = mouseX,
my:Number = mouseY,
dx:Number,
dy:Number,
dist2:Number,
px:Number,
py:Number,
mvx:Number = mx - _oldMouseX,
mvy:Number = my - _oldMouseY,
ms2:Number = Math.sqrt(mvx * mvx + mvy * mvy),
angle:Number,
power:Number,
mag:Number = _range * 0.5;
var p:Number2 = _first;
do
{
px = p.x;
py = p.y;
if (px < 0 || px > sw || py < 0 || py > sh)
{
angle = Math.random() * PI2;
p.x = cx + (Math.random() - 0.5) * 5;
p.y = cy + (Math.random() - 0.5) * 5;
p.vx = (Math.random() - 0.5) * 1 * Math.cos(angle);
p.vy = (Math.random() - 0.5) * 1 * Math.sin(angle);
p.defaultVx = p.vx;
p.defaultVy = p.vy;
}
else
{
dx = px - mx;
dy = py - my;
dist2 = dx * dx + dy * dy;
angle = Math.atan2(dy, dx);
power = mag / dist2 * ms2;
p.vx += power * Math.cos(angle);
p.vy += power * Math.sin(angle);
}
p.defaultVx *= 1.005;
p.defaultVy *= 1.005;
p.vx += (p.defaultVx - p.vx) * 0.05;
p.vy += (p.defaultVy - p.vy) * 0.05;
p.x += p.vx;
p.y += p.vy;
}
while (p = p.next);
_fortune.points = _points;
_oldMouseX = mx;
_oldMouseY = my;
}
private function _draw():void
{
var segments:Vector.<Number2> = _fortune.compute(),
g:Graphics = _canvas.graphics,
p:Number2 = _first,
i:int,
n:int = segments.length,
st:Number2,
ed:Number2,
dx:Number,
dy:Number,
dist2:Number,
thickness:Number,
range:Number = _range,
mx:Number = mouseX,
my:Number = mouseY,
stX:Number,
stY:Number,
edX:Number,
edY:Number;
g.clear();
for (i = 0; i < n; i += 2)
{
st = segments[i ];
ed = segments[i + 1];
stX = st.x;
stY = st.y;
edX = ed.x;
edY = ed.y;
dx = (edX + stX) * 0.5 - mx;
dy = (edY + stY) * 0.5 - my;
dist2 = Math.sqrt(dx * dx + dy * dy);
thickness = (dist2 < range) ? (10 * (range - dist2) / range) : 0;
g.lineStyle(thickness, 0x333333);
g.moveTo(stX, stY);
g.lineTo(edX, edY);
}
g.lineStyle(0, 0xffffff, 0.8);
do
{
g.drawCircle(p.x, p.y, 1);
}
while (p = p.next);
}
}
}
//package
//{
/*public*/ class Number2
{
public var x:Number;
public var y:Number;
public var vx:Number;
public var vy:Number;
public var next:Number2;
public var defaultVx:Number;
public var defaultVy:Number;
public function Number2(x:Number = 0, y:Number = 0, vx:Number = 0, vy:Number = 0):void
{
this.x = x;
this.y = y;
this.defaultVx = this.vx = vx;
this.defaultVy = this.vy = vy;
}
}
//}
//package
//{
/*public*/ class Arc
{
public var p : Number2;
public var next : Arc;
public var prev : Arc;
// public var s0 : Seg;
// public var s1 : Seg;
public var v0 : Number2;
public var v1 : Number2;
// Circle event data :
public var left : Arc;
public var right : Arc;
public var endX : Number;
public var endP : Number2;
}
//}
//package
//{
/*
* An implementation of Steve Fortune's algorithm for computing voronoi diagrams.
* @author Matt Brubeck
*
* Modifications and optimisations:
* ** Data structures are adapted to what's available to as3.
* ** The beachline intersection lookup is optimised,
* intersecting begins only near the probable intersection.
* ** Functions are massively inlined.
*
* Todo list:
* ** Provide for bounding box intersection,
* ** Inline the 'intersection' method.
* ** Design a good datastructure for the solution, which would
* ideally contain enough neighbourhood info for region rendering,
* extrusion and intrusion of edges and pathfinding.
*
* Original c++ code
* http://www.cs.hmc.edu/~mbrubeck/voronoi.html
*/
/*public*/ class Fortune
{
/////////
/////////
///////// Datastructures.
// Points are provided as a vector, which is sorted by x (increasing) before the sweep.
public var points : Vector.<Number2>;
// Bounding box.
private var x0 : Number;
// private var x1 : Number;
// private var y0 : Number;
// private var y1 : Number;
// Root of the frontline and next arc to be removed.
private var root : Arc;
private var next : Arc;
// Reusable objects and pools.
private var o : Number2 = new Number2;
private static var arcPoolD : Arc;
////////
////////
//////// API.
/**
* Computes the Voronoi decomposition of the plane.
* @return A vector or vertices in pairs, describing segments ready for drawing.
*/
public function compute () : Vector.<Number2>
{
//
//
// Clear the output.
var out : Vector.<Number2> = new Vector.<Number2>,
len : int = 0;
//
//
// Clear the state.
root = null;
next = null;
//
//
// Read the pools.
var key : * ,
arcPool : Arc = arcPoolD;
//
//
// Vars:
var i : int,
j : int,
w : Number,
x : Number,
a : Arc,
b : Arc,
// s : Seg,
z : Number2,
p : Number2 = points [ 0 ],
points : Vector.<Number2> = points,
n : int = points.length,
// Circle events check inlined.
circle : Boolean,
eventX : Number,
c : Arc,
d : Arc,
aa : Number2,
bb : Number2,
cc : Number2,
A : Number,
B : Number,
C : Number,
D : Number,
E : Number,
F : Number,
G : Number;
//
// y0 = p.y;
// y1 = p.y;
//
//
// Sort points by x coord, compute the bounding box.
///// Currently insertion sort. Quicksort?
w = points [ 0 ].x;
for ( i = 1; i < n; i ++ )
{
p = points [ i ];
// Keep track of the bounding box.
// if ( p.y < y0 )
// y0 = p.y;
// else if ( p.y > y1 )
// y1 = p.y;
// Insertion sort.
x = p.x;
if ( x < w )
{
j = i;
while ( ( j > 0 ) && ( points [ int ( j - 1 ) ].x > x ) )
{
points [ j ] = points [ int ( j - 1 ) ];
j--;
}
points [ j ] = p;
}
else
w = x;
}
// Get x bounds.
x0 = points [ 0 ].x;
// x1 = points [ n - 1 ].x;
// Add margins to the bounding box.
/*
var dx : Number = (x1 - x0 + 1) / 5.0,
dy : Number = dy = (y1 - y0 + 1) / 5.0;
x0 -= dx;
x1 += dx;
y0 -= dy;
y1 += dy;
// trace ( x0, x1, y0, y1 );
//*/
//
//
// Process.
i = 0;
p = points [ 0 ];
x = p.x;
for ( ;; )
{
//
// Check circle events. /////////////////////////
if ( a )
{
// Check for arc a.
circle = false;
if ( a.prev && a.next )
{
aa = a.prev.p,
bb = a.p,
cc = a.next.p;
// Algorithm from O'Rourke 2ed p. 189.
A = bb.x - aa.x,
B = bb.y - aa.y,
C = cc.x - aa.x,
D = cc.y - aa.y;
// Check that bc is a "right turn" from ab.
if ( A * D - C * B <= 0 )
{
E = A * ( aa.x + bb.x ) + B * ( aa.y + bb.y ),
F = C * ( aa.x + cc.x ) + D * ( aa.y + cc.y ),
G = 2 * ( A * ( cc.y - bb.y ) - B * ( cc.x - bb.x ) );
// Check for colinearity.
// if ( G > 0.000000001 || G < -0.000000001 )
if ( G )
{
// Point o is the center of the circle.
o.x = ( D * E - B * F ) / G;
o.y = ( A * F - C * E ) / G;
// o.x plus radius equals max x coordinate.
A = aa.x - o.x;
B = aa.y - o.y;
eventX = o.x + Math.sqrt ( A * A + B * B );
if ( eventX >= w )
circle = true;
}
}
}
// Remove from queue.
if ( a.right )
a.right.left = a.left;
if ( a.left )
a.left.right = a.right;
if ( a == next )
next = a.right;
// Record event.
if ( circle )
{
a.endX = eventX;
if ( a.endP )
{
a.endP.x = o.x;
a.endP.y = o.y;
}
else
{
a.endP = o;
o = new Number2;
}
d = next;
if ( !d )
{
next = a;
}
else for ( ;; )
{
if ( d.endX >= eventX )
{
a.left = d.left;
if ( d.left )
d.left.right = a;
if ( next == d )
next = a;
a.right = d;
d.left = a;
break;
}
if ( !d.right )
{
d.right = a;
a.left = d;
a.right = null;
break;
}
d = d.right;
}
}
else
{
a.endX = NaN;
a.endP = null;
a.left = null;
a.right = null;
}
// Push next arc to check.
if ( b )
{
a = b;
b = null;
continue;
}
if ( c )
{
a = c;
c = null;
continue;
}
a = null;
}
//////////////////////////////////////////////////
//
if ( next && next.endX <= x )
{
//
// Handle next circle event.
// Get the next event from the queue. ///////////
a = next;
next = a.right;
if ( next )
next.left = null;
a.right = null;
//DEBUG*/ Debug.frontRemove ( a, root );
// Start a new edge.
// s = new Seg;
// s.start = a.endP;
// Remove the associated arc from the front.
if ( a.prev )
{
a.prev.next = a.next;
// a.prev.s1 = s;
a.prev.v1 = a.endP;
}
if ( a.next )
{
a.next.prev = a.prev;
// a.next.s0 = s;
a.next.v0 = a.endP;
}
// Finish the edges before and after a.
/*
if ( a.s0 && !a.s0.done )
{
a.s0.done = true;
// a.s0.end = a.endP;
out [ len ++ ] = a.s0.start;
out [ len ++ ] = a.endP;
}
if ( a.s1 && !a.s1.done )
{
a.s1.done = true;
// a.s1.end = a.endP;
out [ len ++ ] = a.s1.start;
out [ len ++ ] = a.endP;
}
*/
if ( a.v0 )
{
out [ len ++ ] = a.v0;
a.v0 = null;
out [ len ++ ] = a.endP;
}
if ( a.v1 )
{
out [ len ++ ] = a.v1;
a.v1 = null;
out [ len ++ ] = a.endP;
}
// Keep a ref for collection.
d = a;
// Recheck circle events on either side of p:
w = a.endX;
if ( a.prev )
{
b = a.prev;
a = a.next;
}
else
{
a = a.next;
b = null;
}
c = null;
// Collect.
d.v0 = null;
d.v1 = null;
d.p = null;
d.prev = null;
d.endX = NaN;
d.endP = null;
d.next = arcPool;
arcPool = d;
//////////////////////////////////////////////////
//
}
else
{
if ( !p )
break;
//
// Handle next site event. //////////////////////
if ( !root ) {
// root = new Arc;
if ( arcPool )
{
root = arcPool;
arcPool = arcPool.next;
root.next = null;
}
else
root = new Arc;
root.p = p;
//DEBUG*/ Debug.frontInsert ( root, root );
}
else
{
z = new Number2;
// Find the first arc with a point below p,
// and start searching for the intersection around it.
a = root.next;
if ( a )
{
while ( a.next )
{
a = a.next;
if ( a.p.y >= p.y )
break;
}
// Find the intersecting curve.
intersection ( a.prev.p, a.p, p.x, z );
if ( z.y <= p.y )
{
// Search for the intersection to the south of i.
while ( a.next )
{
a = a.next;
intersection ( a.prev.p, a.p, p.x, z );
if ( z.y >= p.y )
{
a = a.prev;
break;
}
}
}
else
{
// Search for the intersection above i.
a = a.prev;
while ( a.prev )
{
a = a.prev;
intersection ( a.p, a.next.p, p.x, z );
if ( z.y <= p.y )
{
a = a.next;
break;
}
}
}
}
else
a = root;
// New parabola will intersect arc a. Duplicate a.
if ( a.next )
{
// b = new Arc;
if ( arcPool )
{
b = arcPool;
arcPool = arcPool.next;
b.next = null;
}
else
b = new Arc;
b.p = a.p;
b.prev = a;
b.next = a.next;
a.next.prev = b;
a.next = b;
}
else
{
// b = new Arc;
if ( arcPool )
{
b = arcPool;
arcPool = arcPool.next;
b.next = null;
}
else
b = new Arc;
b.p = a.p;
b.prev = a;
a.next = b;
}
// a.next.s1 = a.s1;
a.next.v1 = a.v1;
// Find the point of intersection.
z.y = p.y;
z.x = ( a.p.x * a.p.x + ( a.p.y - p.y ) * ( a.p.y - p.y ) - p.x * p.x )
/ ( 2 * a.p.x - 2 * p.x );
// Add p between i and i->next.
// b = new Arc;
if ( arcPool )
{
b = arcPool;
arcPool = arcPool.next;
b.next = null;
}
else
b = new Arc;
b.p = p;
b.prev = a;
b.next = a.next;
a.next.prev = b;
a.next = b;
a = a.next; // Now a points to the new arc.
// Add new half-edges connected to i's endpoints.
/*
s = new Seg;
s.start = z;
a.prev.s1 = a.s0 = s;
s = new Seg;
s.start = z;
a.next.s0 = a.s1 = s;
*/
a.prev.v1 = z;
a.next.v0 = z;
a.v0 = z;
a.v1 = z;
// Check for new circle events around the new arc:
b = a.next;
a = a.prev;
c = null;
w = p.x;
//DEBUG*/ Debug.frontInsert ( a, root );
}
//////////////////////////////////////////////////
//
i ++;
if ( i >= n )
{
p = null;
x = Number.MAX_VALUE;
}
else
{
p = points [ i ];
x = p.x;
}
}
}
//*/
/*
// Clean up dangling edges.
// Advance the sweep line so no parabolas can cross the bounding box.
x = x1;
x = x1 + ( x1 - x0 ) + ( y1 - y0 );
x *= 2;
// Extend each remaining segment to the new parabola intersections.
var arc : Arc = root;
for ( ;; )
{
if ( arc.s1 )
arc.s1.finish ( intersection ( arc.p, arc.next.p, x, new Number2 ) );
arc = arc.next;
if ( !arc.next )
break;
}
//*/
//
//
// Store the pools.
arcPoolD = arcPool;
//
//
// Return the result ready for drawing.
return out;
}
/**
* Where do two parabolas intersect?
* @param p0 A Number2 object describing the site for the first parabola.
* @param p1 A Number2 object describing the site for the second parabola.
* @param l The location of the sweep line.
* @param res A Number2 object in which to store the intersection.
* @return The point of intersection.
*/
public function intersection ( p0 : Number2, p1 : Number2, l : Number, res : Number2 ) : Number2
{
var p : Number2 = p0,
ll : Number = l * l;
if ( p0.x == p1.x )
res.y = ( p0.y + p1.y ) / 2;
else if ( p1.x == l )
res.y = p1.y;
else if ( p0.x == l )
{
res.y = p0.y;
p = p1;
}
else
{
// Use the quadratic formula.
var z0 : Number = 0.5 / ( p0.x - l ); // 1 / ( 2*(p0.x - l) )
var z1 : Number = 0.5 / ( p1.x - l ); // 1 / ( 2*(p1.x - l) )
var a : Number = z0 - z1;
var b : Number = -2 * ( p0.y * z0 - p1.y * z1 );
var c : Number = ( p0.y * p0.y + p0.x * p0.x - ll ) * z0
- ( p1.y * p1.y + p1.x * p1.x - ll ) * z1;
res.y = ( - b - Math.sqrt ( b * b - 4 * a * c ) ) / ( 2 * a );
}
// Plug back into one of the parabola equations.
res.x = ( p.x * p.x + ( p.y - res.y ) * ( p.y - res.y ) - ll )
/ ( 2 * p.x - 2 * l );
return res;
}
}
//}

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