点の動き方

白はマウスの周りを回る
赤は白を追いかける
青は赤を追いかける
赤も青も速度は一定
赤は目標との座標の差で速度を変える
青は目標への方向を見て、進行する角度を変える

by cpu_t 09 Mar 2010

Tags

physics 弹幕
Embed

/**
 * Copyright cpu_t ( http://wonderfl.net/user/cpu_t )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/ft22
 */

// 白はマウスの周りを回る
// 赤は白を追いかける
// 青は赤を追いかける
// 
// 赤も青も速度は一定
// 赤は目標との座標の差で速度を変える
// 青は目標への方向を見て、進行する角度を変える
// 
package {
	import flash.display.Bitmap;
	import flash.display.BitmapData;
    import flash.display.Sprite;
	import flash.events.Event;
	import flash.filters.BlurFilter;
	import flash.geom.ColorTransform;
	import flash.geom.Point;
    public class FlashTest extends Sprite
	{
		private var bmpdata:BitmapData;
		private var lastMousePos:Object;
		private var filter:BlurFilter;
		private var colorTrans:ColorTransform;
        public function FlashTest()
		{
            bmpdata = new BitmapData(stage.stageWidth, stage.stageHeight, false, 0x000000);
			addChild(new Bitmap(bmpdata));
			lastMousePos = { x:0, y:0 };
			filter = new BlurFilter();
			colorTrans = new ColorTransform(.98, .98, .98);
			
			rPos = new Point(0, stage.stageHeight * .5);
			bPos = new Point(stage.stageWidth, stage.stageHeight * .5);
			
			addEventListener(Event.ENTER_FRAME, enterFrameHandler);
        }
		
		private var count:Number = 0;
		private var rPos:Point;
		private var rVec:Point = new Point();
		private var bPos:Point;
		private var bAngle:Number = Math.PI;
		private function enterFrameHandler(e:Event):void 
		{
			bmpdata.lock();
			bmpdata.applyFilter(bmpdata, bmpdata.rect, bmpdata.rect.topLeft, filter);
			bmpdata.colorTransform(bmpdata.rect, colorTrans);
			
			count++;
			var targetPos:Point = new Point(
				mouseX + 60 * Math.cos(count * 10 % 360 * Math.PI / 180),
				mouseY + 60 * Math.sin(count * 12 % 360 * Math.PI / 180)
			);
			
			var v:Point = targetPos.subtract(rPos);
			if (v.length > 10) v.normalize(10);
			rVec.x *= .9;
			rVec.y *= .9;
			rVec = rVec.add(v);
			rVec.normalize(30);
			drawLine(bmpdata, 3, 0xFF0000, rPos, rPos.add(rVec));
			rPos = rPos.add(rVec);
			
			v = rPos.subtract(bPos);
			var da:Number = (Math.atan2(v.y, v.x) - bAngle) % (Math.PI * 2);
			if (da < -Math.PI) da += Math.PI * 2;
			if (da > Math.PI) da -= Math.PI * 2;
			var maxangle:Number = 20 * Math.PI / 180;
			if (da != 0 && Math.abs(da) > maxangle) da = da / Math.abs(da) * maxangle;
			bAngle += da;
			v = bPos.clone();
			bPos.x += Math.cos(bAngle) * 40;
			bPos.y += Math.sin(bAngle) * 40;
			drawLine(bmpdata, 3, 0x0000FF, v, bPos);
			
			drawLine(bmpdata, 3, 0xFFFFFF, lastMousePos, targetPos );
			
			lastMousePos.x = targetPos.x;
			lastMousePos.y = targetPos.y;
			bmpdata.unlock();
		}
		
		private function drawLine(bitmapData:BitmapData, thickness:Number, color:uint, startPos:Object, endPos:Object):void
		{
			if (thickness == 0) return;
			var dx:Number, dy:Number;
			var x:Number = endPos.x - startPos.x;
			var y:Number = endPos.y - startPos.y;
			var m:Number = (y == 0 || Math.abs(x / y) >= 1) ? x : y;
			if (m == 0)
			{
				for (dy = -thickness * .5; dy <= thickness * .5; dy++)
				{
					for (dx = -thickness * .5; dx <= thickness * .5; dx++)
					{
						bitmapData.setPixel(startPos.x + dx, startPos.y + dy, color);
					}
				}
				return;
			}
			for (var i:Number = 0; i / m <= 1; i += (m == 0 ? 0 : (m / Math.abs(m))))
			{
				var tx:Number = startPos.x + x / m * i;
				var ty:Number = startPos.y + y / m * i;
				if (thickness == 1 || thickness < 0)
				{
					bitmapData.setPixel(tx, ty, color);
				}
				else
				{
					for (dy = -thickness * .5; dy <= thickness * .5; dy++)
					{
						for (dx = -thickness * .5; dx <= thickness * .5; dx++)
						{
							bitmapData.setPixel(tx + dx, ty + dy, color);
						}
					}
				}
			}
		}
    }
}