javascript - 返回交点位置和大小

Question

我正在开发一个游戏，我发现了 ( a problem )，为了解决它，我需要返回交叉点位置和大小。

这是矩形碰撞检测代码:

for (var i = 0; i < rects.length; i++) {
    for (var others = 0; others < rects.length; others++) {
        if (others != i) {
            if (rects[others].y + rects[others].height >= rects[i].y &&
                rects[others].x + rects[others].width >= rects[i].x &&
                rects[others].x <= rects[i].x + rects[i].width &&
                rects[others].y <= rects[i].y + rects[i].height) {
                // They're intersecting!
                intery = 0; // Intersection Y
                interx = 0; // Intersection X
                interw = 0; // Intersection Width
                interh = 0; // Intersection Height
            }
        }
    }
}

Answer 1

演示:http://jsfiddle.net/m1erickson/TqRxG/

如果你有 2 个像这样定义的矩形:

var r1={
  x:40,
  y:40,
  w:50,
  h:30,
}

var r2={
  x:60,
  y:60,
  w:50,
  h:30,
}

然后你可以像这样计算它们的交集矩形(如果有):

function intersectingRect(r1,r2){
  var x=Math.max(r1.x,r2.x);
  var y=Math.max(r1.y,r2.y);
  var xx=Math.min(r1.x+r1.w,r2.x+r2.w);
  var yy=Math.min(r1.y+r1.h,r2.y+r2.h);
  return({x:x,y:y,w:xx-x,h:yy-y});
}

[添加:检测圆与矩形碰撞]

如果你有一个这样定义的圆:

var c={
    x:50,
    y:50,
    r:15
}

然后你可以像这样确定圆形和矩形是否发生碰撞:

function RectCircleColliding(circle,rect){
    var distX = Math.abs(circle.x - rect.x-rect.w/2);
    var distY = Math.abs(circle.y - rect.y-rect.h/2);
    if (distX > (rect.w/2 + circle.r)) { return false; }
    if (distY > (rect.h/2 + circle.r)) { return false; }
    if (distX <= (rect.w/2)) { return true; } 
    if (distY <= (rect.h/2)) { return true; }
    var dx=distX-rect.w/2;
    var dy=distY-rect.h/2;
    return (dx*dx+dy*dy<=(circle.r*circle.r));
}