碰撞检测:
1、圆形与矩形的碰撞检测
函数ComputeCollision,当相对距离小于圆形半径的时候为碰撞。
参数介绍(w:矩形的宽,h:矩形的高,r:圆形半径,rx:圆形中心与矩形中心相对坐标X,ry:圆形中心与矩形中心相对坐标Y)
function ComputeCollision(w, h, r, rx, ry) { var dx = Math.min(rx, w * 0.5); var dx1 = Math.max(dx, -w * 0.5); var dy = Math.min(ry, h * 0.5); var dy1 = Math.max(dy, -h * 0.5); return (dx1 - rx) * (dx1 - rx) + (dy1 - ry) * (dy1 - ry) <= r * r; }
2、圆形坐标中心位置和矩形坐标中心位置
圆形坐标指鼠标的位置
修正圆形的位置,让鼠标在圆心的中心位置
//圆心坐标 var radiusPosX = parseInt((event.clientX || event.x)); var radiusPosY = parseInt((event.clientY || event.y)); event = event || window.event; //让鼠标在圆心的位置 circle.style.left = parseInt(radiusPosX - radius) + "px"; circle.style.top = parseInt(radiusPosY - radius) + "px";
矩形的长宽
矩形的中心位置是(相对距左+宽度,相对距顶+高度)。
//矩形的长宽 var rectW = rect.clientWidth; var rectH = rect.clientHeight; //矩形中心坐标 var rectPosX = parseInt(rect.offsetLeft) + rectW / 2; var rectPosY = parseInt(rect.offsetTop) + rectH / 2;
<!DOCTYPE html> <html> <head> <title>碰撞检测</title> <style type="text/css"> *{margin: 0px;padding: 0px;} #circle{width: 80px;height: 80px;border: 1px solid #FF0000;border-radius: 50px;background: #FF6600;position: absolute;left: 0px;top: 0px;} #rect{width: 150px;height: 150px;background: #00FF00;position: absolute;left: 200px;top: 50px;} </style> </head> <body> <div id="circle"><br /></div><div id="rect"><br /></div><script type="text/javascript"> //圆形与矩形的碰撞检测 function ComputeCollision(w, h, r, rx, ry) { var dx = Math.min(rx, w * 0.5); var dx1 = Math.max(dx, -w * 0.5); var dy = Math.min(ry, h * 0.5); var dy1 = Math.max(dy, -h * 0.5); return (dx1 - rx) * (dx1 - rx) + (dy1 - ry) * (dy1 - ry) <= r * r; } window.onload = function () { document.onmousemove = function (event) { var circle = document.getElementById("circle"); //圆的半径 var radius = circle.clientWidth / 2; //圆心坐标 var radiusPosX = parseInt((event.clientX || event.x)); var radiusPosY = parseInt((event.clientY || event.y)); event = event || window.event; //让鼠标在圆心的位置 circle.style.left = parseInt(radiusPosX - radius) + "px"; circle.style.top = parseInt(radiusPosY - radius) + "px"; var rect = document.getElementById("rect"); //矩形的长宽 var rectW = rect.clientWidth; var rectH = rect.clientHeight; //矩形中心坐标 var rectPosX = parseInt(rect.offsetLeft) + rectW / 2; var rectPosY = parseInt(rect.offsetTop) + rectH / 2; //圆形中心与矩形中心相对坐标 var rx = radiusPosX - rectPosX; var ry = radiusPosY - rectPosY; //碰撞检测 if (ComputeCollision(rectW, rectH, radius, rx, ry)) { rect.style.background = "#00F0FF"; } else { rect.style.background = "#00FF00"; } } } </script> </body> </html>