如何获得像素完美的BitmapData碰撞的上，下，最右和最左点？这是我的碰撞检测代码：
public static function checkCollision(object1:*, object2:*, debug:Boolean = false):Boolean{
var object1Rect:Rectangle = object1.getRect(stage);
var object2Rect:Rectangle = object2.getRect(stage);
var object1Point:Point = new Point(object1Rect.x, object1Rect.y);
var object2Point:Point = new Point(object2Rect.x, object2Rect.y);
var bitmapData1:BitmapData = new BitmapData(
object1Rect.width,
object1Rect.height,
true,
0
);
var bitmapData2:BitmapData = new BitmapData(
object2Rect.width,
object2Rect.height,
true,
0
);
var clr:ColorTransform = new ColorTransform();
if(debug)
clr.color = 0x00ff00;
bitmapData1.draw(object1, new Matrix(1, 0, 0, 1, -object1Rect.x, -object1Rect.y), clr);
bitmapData2.draw(object2, null, clr);
if(debug){
if(bmp1.stage)
stage.removeChild(bmp1);
bmp1 = new Bitmap(bitmapData1);
bmp1.x = object1Point.x;
bmp1.y = object1Point.y;
stage.addChild(bmp1);
if(bmp2.stage)
stage.removeChild(bmp2);
bmp2 = new Bitmap(bitmapData2);
bmp2.x = object2Point.x;
bmp2.y = object2Point.y;
stage.addChild(bmp2);
}
var bCollide:Boolean = bitmapData1.hitTest(
object1Point,
255,
bitmapData2,
object2Point,
255
);
if(!debug){
bitmapData1.dispose();
bitmapData2.dispose();
}
return bCollide;
}
它完美无缺。但是，我用来检测顶部生命值的代码不能正常工作。这是代码：
public static function getHitPoint(object1:*, object2:*):Point{
var point:Point = new Point();
var object1Rect:Rectangle = object1.getRect(stage);
var object2Rect:Rectangle = object2.getRect(stage);
var object1Point:Point = new Point(object1Rect.x, object1Rect.y);
var object2Point:Point = new Point(object2Rect.x, object2Rect.y);
var bitmapData1:BitmapData = new BitmapData(
object1.width,
object1.height,
true,
0
);
var bitmapData2:BitmapData = new BitmapData(
object2.width,
object2.height,
true,
0
);
bitmapData1.draw(object1, new Matrix(1, 0, 0, 1, -object1Rect.x, -object1Rect.y));
bitmapData2.draw(object2);
var bitmap1:Bitmap = new Bitmap(bitmapData1);
var bitmap2:Bitmap = new Bitmap(bitmapData2);
bitmap1.x = object1Point.x;
bitmap1.y = object1Point.y;
bitmap2.x = object2Point.x;
bitmap2.y = object2Point.y;
var bitmapOrigin:Point = new Point(object1Point.x, object1Point.y);
var bitmap2OriginLocal:Point = bitmap2.globalToLocal(bitmapOrigin);
var overlappingPixels:Vector.<uint> = bitmap2.bitmapData.getVector(
new Rectangle(bitmap2OriginLocal.x, bitmap2OriginLocal.y, object1Rect.width, object1Rect.height)
);
for(var i:String in overlappingPixels){
var index:uint = uint(i);
if(overlappingPixels[i] != 0){
point.x = (index % object1.width) + (bitmap2.x > bitmap1.x ? bitmap2.x : bitmap1.x);
point.y = (uint(index / bitmap1.height)) + (bitmap2.y > bitmap1.y ? bitmap2.y : bitmap1.y);
break;
}
}
return point;
}
我不知道为什么，但getHitPoint()函数有时会返回错误的坐标。任何人都可以解释为什么会这样吗？我怎样才能检测最底部，最左边和最右边的生命值？
修改
我现在知道为什么getHitPoint()有时会返回错误的值：point.y = (uint(index / bitmap1.height)) + (bitmap2.y > bitmap1.y ? bitmap2.y : bitmap1.y);应为point.y = (uint(index/bitmap1. width )) + (bitmap2.y > bitmap1.y ? bitmap2.y : bitmap1.y);
编辑2
我发现了如何获得最低点：
public static function getHitPoint(object1:*, object2:*, direction:int = 0):*{
var point:Point = new Point();
var object1Rect:Rectangle = object1.getRect(stage);
var object2Rect:Rectangle = object2.getRect(stage);
var object1Point:Point = new Point(object1Rect.x, object1Rect.y);
var object2Point:Point = new Point(object2Rect.x, object2Rect.y);
var bitmapData1:BitmapData = new BitmapData(
Math.round(object1Rect.width),
Math.round(object1Rect.height),
true,
0
);
var bitmapData2:BitmapData = new BitmapData(
Math.round(object2Rect.width),
Math.round(object2Rect.height),
true,
0
);
bitmapData1.draw(object1, new Matrix(1, 0, 0, 1, -object1Rect.x, -object1Rect.y));
bitmapData2.draw(object2);
var bitmap1:Bitmap = new Bitmap(bitmapData1);
var bitmap2:Bitmap = new Bitmap(bitmapData2);
bitmap1.x = object1Point.x;
bitmap1.y = object1Point.y;
bitmap2.x = object2Point.x;
bitmap2.y = object2Point.y;
var bitmapOrigin:Point = new Point(object1Point.x, object1Point.y);
var bitmap2OriginLocal:Point = bitmap2.globalToLocal(bitmapOrigin);
var overlappingPixels:Vector.<uint> = bitmap2.bitmapData.getVector(
new Rectangle(bitmap2OriginLocal.x, bitmap2OriginLocal.y, object1Rect.width, object1Rect.height)
);
switch(direction){
case 0: //top
for(var i:String in overlappingPixels){
var index:uint = uint(i);
if(overlappingPixels[i] != 0){
point.x = (index % bitmap1.width) + (bitmap2.x > bitmap1.x ? bitmap2.x : bitmap1.x);
point.y = (uint((index)/bitmap1.width)) + (bitmap2.y > bitmap1.y ? bitmap2.y : bitmap1.y);
return point;
}
}
case 1: //right
// I still need this
case 2: //bottom
overlappingPixels.reverse();
for(var i:String in overlappingPixels){
var index:uint = uint(i);
if(overlappingPixels[i] != 0){
point.x = bitmap1.width - (index % bitmap1.width) + (bitmap2.x > bitmap1.x ? bitmap2.x : bitmap1.x);
point.y = (bitmap2.y + bitmap2.height > bitmap1.y + bitmap1.height ? bitmap1.y + bitmap1.height : bitmap2.y + bitmap2.height) - (uint(index/bitmap1.width));
return point;
}
}
case 3: //left
// I still need this too
}
return false;
}
我仍然需要一种方法来获得最左边和最右边的生命值
答案 0 :(得分：0)
你不需要像在那里那样去做。您可以在单个函数中完成所有操作，这将正确返回所有内容。我在下面添加了评论。请注意我已经改变的内容，就像你现在正在尝试的那样，使用你改变的代码，这是不可能的。
这适用于任何形状，任何方向。它会给你确切的碰撞X和Y.
请不要将其变为静态功能。将它放入一个全局类中，然后使用Singleton来管理它。当您使用静态函数并引用阶段时，事情开始变得非常严重。
此外，如果您要使用小于1的像素值（即99.75），则需要进行一些调整以适应这一点。考虑到你的Math.round用法，我假设你正在使用整个像素。
/**
*
* @param object1
* @param object2
* @return
*/
private function getHitPoint(object1:*, object2:*):*{
var point:Point;
// X and Y where we hit
// do NOT change this to a stage location or it does NOT work
var object1Point:Point = new Point(object1.x, object1.y);
var object2Point:Point = new Point(object2.x, object2.y);
var bitmapData1:BitmapData = new BitmapData(
Math.round(object1.width),
Math.round(object1.height),
true,
0
);
var bitmapData2:BitmapData = new BitmapData(
Math.round(object2.width),
Math.round(object2.height),
true,
0
);
// Draw
bitmapData1.draw(object1, new Matrix(1, 0, 0, 1, -object1.x, -object1.y));
bitmapData2.draw(object2);
// Create BMP's
var bitmap1:Bitmap = new Bitmap(bitmapData1);
var bitmap2:Bitmap = new Bitmap(bitmapData2);
// Set X and Y and BMP
bitmap1.x = object1Point.x;
bitmap1.y = object1Point.y;
bitmap2.x = object2Point.x;
bitmap2.y = object2Point.y;
// BMP origin is the object1 X and Y
var bitmapOrigin:Point = new Point(object1Point.x, object1Point.y);
// Create a local version of the bitmap2 so we can see what is overlapping
var bitmap2OriginLocal:Point = bitmap2.globalToLocal(bitmapOrigin);
// Create a rectangle from what we now know
var rect:Rectangle = new Rectangle(bitmap2OriginLocal.x, bitmap2OriginLocal.y, object1.width, object1.height);
// The overlapping pixels are within the rectangle, so get them all
var overlappingPixels:Vector.<uint> = bitmap2.bitmapData.getVector(rect);
// Run through all the overlapping pixels until we find a colourful one
for (var i:uint = 0; i < overlappingPixels.length; i++ ) {
var index:uint = overlappingPixels[i];
// If the colour is not 0, we have found it
if(index != 0){
point = new Point();
// Basically, instead of using width and getting 100, we're working out how
// many pixles across the overlap is. The Vector doesn't tell us this, so we need to work it out
var overlappingWidth:uint = object1.width - Math.abs(bitmap2OriginLocal.x);
// The Y is object1.y, minus the local y, plus object1's width minus the X from the local
point.y = object1.y - bitmap2OriginLocal.y + uint(i / overlappingWidth);
// The X is the same as above, but % of the width
point.x = object1.x - bitmap2OriginLocal.x + (i % overlappingWidth);
// Found it, we're done
break;
}
}
// Only fires when you've got a collision that is less than 1 pixel from the width or height
// Just a fail safe
if (!point) {
point = new Point(object1.width, object1.height);
}
return point;
}
对于上下文，我的整个课程在下面显示了我如何使用此功能。您可以复制/粘贴此类，它将起作用。它显示了如何在屏幕上移动精灵，一旦发现碰撞，它就可以解决碰撞发生的位置。
此类用于绝对像素完美碰撞检测，包括一个示例。
package kazo
{
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Point;
import flash.geom.Rectangle;
import flash.geom.Matrix;
/**
* ...
* @author KM
*/
public class TestCases2 extends Sprite
{
private var rect :Sprite;
private var circle :Sprite;
/**
*
*/
public function TestCases2()
{
addEventListener(Event.ADDED_TO_STAGE, init);
}
public function init(e:Event):void {
removeEventListener(Event.ADDED_TO_STAGE, init);
trace('Starting test case');
// Rectangle
rect = new Sprite();
// Circle
circle = new Sprite();
// Draw the rectangle. Center point must be TOP LEFT
// If you're using Flash Professional, place everything at 0,0 inside the MC
rect.graphics.beginFill(0xff0000);
rect.graphics.drawRect(0, 0, 100, 100);
rect.graphics.endFill();
// Draw the circle. Center point is TOP LEFT, so the X and Y of the circle need to be equal to the radius
circle.graphics.beginFill(0xffff00);
circle.graphics.drawCircle(50, 50, 50);
circle.graphics.endFill();
// Add them
addChild(rect);
addChild(circle);
// Position
rect.x = 225;
rect.y = 75;
// Position
circle.x = 225;
circle.y = 225;
// Frame loop
addEventListener(Event.ENTER_FRAME, frameFunc);
}
/**
*
* @param e
*/
private function frameFunc(e:Event):void {
// move them around
circle.y -= 2;
circle.x += 0;
rect.y += 1;
rect.x += 0;
// Check for collisions. If found, stop. Pass 'true' as the final param if you want it to draw to the screen
if (checkCollision(rect, circle)) {
var ref:Point = getHitPoint(rect, circle);
// Draws where the collision hit
var loc:Sprite = new Sprite();
loc.graphics.beginFill(0x000000);
loc.graphics.drawRect(0, 0, 10, 10);
loc.graphics.endFill();
addChild(loc);
loc.x = ref.x;
loc.y = ref.y;
trace(ref);
removeEventListener(Event.ENTER_FRAME, frameFunc);
}
}
/**
*
* @param _obj1
* @param _obj2
* @param _debug
* @return
*/
private function checkCollision(_obj1:Sprite, _obj2:Sprite, _debug:Boolean = false):Boolean {
// Draw the first item to bitmapdata
var bmd1:BitmapData = new BitmapData(_obj1.width, _obj1.height, true, 0);
// ..and the second
var bmd2:BitmapData = new BitmapData(_obj2.width, _obj2.height, true, 0);
// Now draw them
bmd1.draw(_obj1);
bmd2.draw(_obj2);
// If we're in debug, also add the bitmap to the stage so we can see where we are
if (_debug) {
var bmp:Bitmap = new Bitmap(bmd1);
bmp.x = _obj1.x;
bmp.y = _obj1.y;
addChild(bmp);
var bmp2:Bitmap = new Bitmap(bmd2);
bmp2.x = _obj2.x;
bmp2.y = _obj2.y;
addChild(bmp2);
}
// Hit test including alpha channel. Obj1 X/Y, Obj2 X/Y, alpha channel
var rtn:Boolean = bmd1.hitTest(new Point(_obj1.x, _obj1.y), 255, bmd2, new Point(_obj2.x, _obj2.y), 255);
// Dispose the bitmap data, we dont need it anymore
if (!_debug) {
bmd1.dispose();
bmd2.dispose();
}
// Return the boolean
return rtn;
}
/**
*
* @param object1
* @param object2
* @return
*/
private function getHitPoint(object1:*, object2:*):*{
var point:Point;
// X and Y where we hit
// do NOT change this to a stage location or it does NOT work
var object1Point:Point = new Point(object1.x, object1.y);
var object2Point:Point = new Point(object2.x, object2.y);
var bitmapData1:BitmapData = new BitmapData(
Math.round(object1.width),
Math.round(object1.height),
true,
0
);
var bitmapData2:BitmapData = new BitmapData(
Math.round(object2.width),
Math.round(object2.height),
true,
0
);
// Draw
bitmapData1.draw(object1, new Matrix(1, 0, 0, 1, -object1.x, -object1.y));
bitmapData2.draw(object2);
// Create BMP's
var bitmap1:Bitmap = new Bitmap(bitmapData1);
var bitmap2:Bitmap = new Bitmap(bitmapData2);
// Set X and Y and BMP
bitmap1.x = object1Point.x;
bitmap1.y = object1Point.y;
bitmap2.x = object2Point.x;
bitmap2.y = object2Point.y;
// BMP origin is the object1 X and Y
var bitmapOrigin:Point = new Point(object1Point.x, object1Point.y);
// Create a local version of the bitmap2 so we can see what is overlapping
var bitmap2OriginLocal:Point = bitmap2.globalToLocal(bitmapOrigin);
// Create a rectangle from what we now know
var rect:Rectangle = new Rectangle(bitmap2OriginLocal.x, bitmap2OriginLocal.y, object1.width, object1.height);
// The overlapping pixels are within the rectangle, so get them all
var overlappingPixels:Vector.<uint> = bitmap2.bitmapData.getVector(rect);
// Run through all the overlapping pixels until we find a colourful one
for (var i:uint = 0; i < overlappingPixels.length; i++ ) {
var index:uint = overlappingPixels[i];
// If the colour is not 0, we have found it
if(index != 0){
point = new Point();
// Basically, instead of using width and getting 100, we're working out how
// many pixles across the overlap is. The Vector doesn't tell us this, so we need to work it out
var overlappingWidth:uint = object1.width - Math.abs(bitmap2OriginLocal.x);
// The Y is object1.y, minus the local y, plus object1's width minus the X from the local
point.y = object1.y - bitmap2OriginLocal.y + uint(i / overlappingWidth);
// The X is the same as above, but % of the width
point.x = object1.x - bitmap2OriginLocal.x + (i % overlappingWidth);
// Found it, we're done
break;
}
}
// Only fires when you've got a collision that is less than 1 pixel from the width or height
// Just a fail safe
if (!point) {
point = new Point(object1.width, object1.height);
}
return point;
}
}
}