我正在尝试制作用户使用鼠标绘制的迷宫，如果他们撞到墙壁，它会删除他们刚绘制的线条。我有一个带有alpha的png文件，可以创建迷宫的墙壁。
我需要用户在alpha上绘制，但是当他们点击非alpha时，它会触发操作并删除该行。
以下是我遇到的问题：
if (myshape.hitTestPoint(theBall.x,theBall.y, true))
以下是完整代码：
package
{
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.display.DisplayObject;
import flash.display.Graphics;
import flash.display.JointStyle;
import flash.display.LineScaleMode;
import flash.display.Shape;
import flash.display.Sprite;
import flash.events.*;
public class MazeClass extends Sprite
{
//Are we drawing or not?
private var drawing:Boolean;
public var myshape:Shape;
public var alreadyDrawn:Shape;
public var theBall:Ball = new Ball();
//alreadyDrawn = new Shape();
public function MazeClass()
{
if (stage)
{
myshape = new Shape();
myshape.graphics.lineStyle(12,0x000000);
addChild(myshape);
drawing = false;//to start with
stage.addEventListener(MouseEvent.MOUSE_DOWN, startDrawing);
stage.addEventListener(MouseEvent.MOUSE_MOVE, draw);
stage.addEventListener(MouseEvent.MOUSE_UP, stopDrawing);
//stage.addEventListener(Event.ENTER_FRAME, checkIt);
addChild(theBall);
}
}
public function startDrawing(event:MouseEvent):void
{
myshape.graphics.moveTo( mouseX, mouseY);
drawing = true;
}
public function draw(event:MouseEvent)
{
if (drawing)
{
//checkIt();
myshape.graphics.lineTo(mouseX,mouseY);
if (myshape.hitTestPoint(theBall.x,theBall.y, true))
{
trace("Hit A WALL!");
myshape.graphics.clear();
myshape.graphics.lineStyle(12, 0xFFFFFF);
myshape.graphics.moveTo(mouseX,mouseY);
}
}
}
public function stopDrawing(event:MouseEvent)
{
drawing = false;
}
}
}
答案 0 :(得分：0)
另一种选择是测试对应于“玩家位置”的地图位图数据像素的颜色（在这种情况下，绘制线的末尾）：
var testPixel:uint = _myBitmapData.getPixel(xPosition, yPosition);
或者您可以使用.getPixel32，其中包含返回的uint中的alpha。
答案 1 :(得分：0)
我发现了一个工作解决方案：
感谢fsbmain，我找到了一个有效的解决方案。谢谢。我发布了我的完整代码，希望这可以帮助其他人。
最后我不得不使用另一部movieClip而不是鼠标，但这对我有用。现在，他们不得不在迷宫中的任何地方画画，而是必须通过迷宫拖动一个名叫Beau的小角色。这对我来说效果更好。
很高兴知道如何检测鼠标或我绘制的实际线是否也会撞墙。也许有人可以提出建议。不过，谢谢你帮助我做到这一点。
可以在这里找到使我的movieClip检测到alpha的简短而必要的代码。与我发现的其他复杂选项相比，它确实很短。这是链接：http://www.mikechambers.com/blog/2009/06/24/using-bitmapdata-hittest-for-collision-detection/
package
{
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.display.DisplayObject;
import flash.display.Graphics;
import flash.display.JointStyle;
import flash.display.LineScaleMode;
import flash.display.Shape;
import flash.display.Sprite;
import flash.events.*;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
import flash.events.TouchEvent;
import flash.ui.Multitouch;
import flash.ui.MultitouchInputMode;
import flash.desktop.NativeApplication;
import flash.system.Capabilities;
import flash.display.*;
import flash.geom.*;
import flash.display.BitmapData;
import flash.display.Bitmap;
import flash.geom.Matrix;
public class MazeClass extends Sprite
{
//Are we drawing or not?
private var drawing:Boolean;
public var myshape:Shape;
public var alreadyDrawn:Shape;
public var theMap:*;
public var swiper:Swiper = new Swiper();
public var Beau:littleBeau = new littleBeau();
//alreadyDrawn = new Shape();
public var currentGalleryItem:Number = 1;
public var totalGalleryItems:Number = 4;
public var redClipBmpData:BitmapData;
public var blueClipBmpData:BitmapData;
public var redRect:Rectangle;
public var blueRect:Rectangle;
public function MazeClass()
{
if (stage)
{
theMap = new MapOne();
myshape = new Shape();
myshape.graphics.lineStyle(33,0x0aa6df);
addChild(myshape);
drawing = false;//to start with
stage.addEventListener(MouseEvent.MOUSE_DOWN, startDrawing);
stage.addEventListener(MouseEvent.MOUSE_MOVE, draw);
stage.addEventListener(MouseEvent.MOUSE_UP, stopDrawing);
//stage.addEventListener(Event.ENTER_FRAME, checkIt);
stage.addEventListener(KeyboardEvent.KEY_UP, fl_OptionsMenuHandler);
Multitouch.inputMode = MultitouchInputMode.GESTURE;
addChild(theMap);
//theMap.height = stage.stageHeight - 200;
theMap.theStart.alpha = 0;
theMap.theFinish.alpha = 0;
addChild(swiper);
swiper.y = stage.stageHeight - swiper.height;
swiper.addEventListener(TransformGestureEvent.GESTURE_SWIPE, fl_SwipeToGoToNextPreviousFrame);
addChild(Beau);
Beau.x = theMap.theStart.x;
Beau.y = theMap.theStart.y - swiper.height;
Beau.addEventListener(MouseEvent.MOUSE_DOWN, BeauStartDrag);
Beau.addEventListener(MouseEvent.MOUSE_UP, BeauStopDrag);
redRect = theMap.getBounds(this);
redClipBmpData = new BitmapData(redRect.width,redRect.height,true,0);
redClipBmpData.draw(theMap);
blueRect = Beau.getBounds(this);
blueClipBmpData = new BitmapData(blueRect.width,blueRect.height,true,0);
blueClipBmpData.draw(Beau);
//blueClipBmpData.x = theMap.theStart.x;
//blueClipBmpData.y = theMap.theStart.y - swiper.height;
stage.addEventListener(Event.ENTER_FRAME, enterFrame);
}
}
public function enterFrame(e:Event):void
{
//Beau.x = mouseX;
//Beau.y = mouseY;
if (redClipBmpData.hitTest(new Point(theMap.x, theMap.y),
255,
blueClipBmpData,
new Point(Beau.x, Beau.y),
255
))
{
trace("hit");
clearAll();
//redClip.filters = [new GlowFilter()];
}
else
{
trace("No Hit");
}
}
public function BeauStartDrag(event:MouseEvent):void
{
Beau.startDrag();
drawing = true;
}
public function BeauStopDrag(event:MouseEvent):void
{
drawing = false;
Beau.stopDrag();
}
public function startDrawing(event:MouseEvent):void
{
myshape.graphics.moveTo( mouseX, mouseY);
}
//drawing = true;
public function draw(event:MouseEvent)
{
if (drawing)
{
//checkIt();
myshape.graphics.lineTo(mouseX,mouseY);
}
}
public function stopDrawing(event:MouseEvent)
{
//drawing = false;
}
public function fl_OptionsMenuHandler(event:KeyboardEvent):void
{
if ((event.keyCode == 95) || (event.keyCode == Keyboard.MENU))
{
NativeApplication.nativeApplication.exit(0);
}
}
public function clearAll()
{
myshape.graphics.clear();
myshape.graphics.lineStyle(12, 0x0aa6df);
myshape.graphics.moveTo(mouseX,mouseY);
Beau.x = theMap.theStart.x;
Beau.y = theMap.theStart.y - swiper.height;
drawing = false;
Beau.stopDrag();
}
public function fl_SwipeToGoToNextPreviousFrame(event:TransformGestureEvent):void
{
if (event.offsetX == 1)
{
if (currentGalleryItem > 1)
{
currentGalleryItem--;
trace("swipe Right");
clearAll();
removeChild(theMap);
theMap = new MapOne();
addChild(theMap);
theMap.height = stage.stageHeight - 200;
theMap.theStart.alpha = 0;
theMap.theFinish.alpha = 0;
addChild(Beau);
Beau.x = theMap.theStart.x;
Beau.y = theMap.theStart.y - swiper.height;
}
}
else if (event.offsetX == -1)
{
if (currentGalleryItem < totalGalleryItems)
{
currentGalleryItem++;
trace("swipe Left");
clearAll();
removeChild(theMap);
theMap = new MapTwo();
addChild(theMap);
theMap.height = stage.stageHeight - 200;
theMap.theStart.alpha = 0;
theMap.theFinish.alpha = 0;
addChild(Beau);
Beau.x = theMap.theStart.x;
Beau.y = theMap.theStart.y - swiper.height;
}
}
}
}
}