1
所以在我的畫布上我有一個大的橢圓,當用戶點擊畫布時,應該在大橢圓的邊緣上創建一個小橢圓, 。這些角度是關閉的,我對計算不是很有信心,再加上我認爲這個座標系在下降時增加的事實正在讓它變得更糟。任何人都可以幫助我獲得理想的結果嗎?計算從一個點到另一個的角度
HTML
<html>
<head>
<script src='processing-1.4.1.min.js'></script>
<script src='jquery-1.9.1.min.js'></script>
</head>
<body>
<canvas id="gamecanvas" data-processing-sources="canvas.pde"></canvas>
</body>
<script>
var gamecanvas = document.getElementById("gamecanvas");
var projectiles = [];
$("#gamecanvas").click(function(e) {
var x = e.clientX - gamecanvas.offsetLeft;
var y = e.clientY - gamecanvas.offsetTop;
var pindex = projectiles.length;
projectiles[pindex] = [];
projectiles[pindex]['angle'] = Math.atan2(y - 200, x - 300) * 180/Math.PI;
projectiles[pindex]['x'] = 300 + 10 * Math.cos(projectiles[pindex]['angle']);
projectiles[pindex]['y'] = 200 + 10 * Math.sin(projectiles[pindex]['angle']);
});
</script>
</html>
Processing.js帆布素描(Reference)
void draw() {
size(600,400);
background(255,255,255);
fill(#FF0000);
ellipse(300,200,15,15);
for(i = 0;i < projectiles.length;i++) {
ellipse(projectiles[i]['x'],projectiles[i]['y'],2,2);
}
}