我想绘制一个随机的曲面blob在画布上,但我似乎无法想出一个算法来做到这一点。我试图创建这样的随机贝塞尔曲线:帆布“随机”弯曲的形状
context.beginPath();
// Each shape should be made up of between three and six curves
var i = random(3, 6);
var startPos = {
x : random(0, canvas.width),
y : random(0, canvas.height)
};
context.moveTo(startPos.x, startPos.y);
while (i--) {
angle = random(0, 360);
// each line shouldn't be too long
length = random(0, canvas.width/5);
endPos = getLineEndPoint(startPos, length, angle);
bezier1Angle = random(angle - 90, angle + 90) % 360;
bezier2Angle = (180 + random(angle - 90, angle + 90)) % 360;
bezier1Length = random(0, length/2);
bezier2Length = random(0, length/2);
bezier1Pos = getLineEndPoint(startPos, bezier1Length, bezier1Angle);
bezier2Pos = getLineEndPoint(endPos, bezier2Length, bezier2Angle);
context.bezierCurveTo(
bezier1Pos.x, bezier1Pos.y
bezier2Pos.x, bezier2Pos.y
endPos.x, endPos.y
);
startPos = endPos;
}
(这是一种简化...我加约束的线位在画面内等) 的问题,这是得到了头回到起点,并且不仅仅是制造大量的尴尬角落。有没有人知道有一个更好的算法来做到这一点,或者可以想出一个呢?
编辑:我已经取得了一些进展。我再次开始,用直线工作(我想我知道该做点什么才能让他们顺利进入Beziers)。我已经设置了它,以便在绘制每个点之前,它会计算出距离前一个点的距离和角度。如果距离小于一定量,则关闭曲线。否则,根据迭代次数,可能的角度变窄,最大线长度是到起点的距离。所以这是一些代码。
start = {
// start somewhere within the canvas element
x: random(canvas.width),
y: random(canvas.height)
};
context.moveTo(start.x, start.y);
prev = {};
prev.length = random(minLineLength, maxLineLength);
prev.angle = random(360);
prev.x = start.x + prev.length * Math.cos(prev.angle);
prev.y = start.y + prev.length * Math.sin(prev.angle);
j = 1;
keepGoing = true;
while (keepGoing) {
j++;
distanceBackToStart = Math.round(
Math.sqrt(Math.pow(prev.x - start.x, 2) + Math.pow(prev.y - start.y, 2)));
angleBackToStart = (Math.atan((prev.y - start.y)/(prev.x - start.x)) * 180/Math.pi) % 360;
if (isNaN(angleBackToStart)) {
angleBackToStart = random(360);
}
current = {};
if (distanceBackToStart > minLineLength) {
current.length = random(minLineLength, distanceBackToStart);
current.angle = random(angleBackToStart - 90/j, angleBackToStart + 90/j) % 360;
current.x = prev.x + current.length * Math.cos(current.angle);
current.y = prev.y + current.length * Math.sin(current.angle);
prev = current;
} else {
// if there's only a short distance back to the start, join up the curve
current.length = distanceBackToStart;
current.angle = angleBackToStart;
current.x = start.x;
current.y = start.y;
keepGoing = false;
}
context.lineTo(current.x, current.y);
}
console.log('Shape complexity: ' + j);
context.closePath();
context.fillStyle = 'black';
context.shadowColor = 'black';
context.shadowOffsetX = -xOffset;
context.shadowOffsetY = -yOffset;
context.shadowBlur = 50;
context.fill();
我现在已经得到的问题是,该形状的轮廓往往跨越本身,它看起来是错误的。我能想到解决这个问题的唯一方法是跟踪边界框,并且每个新点都应始终走出边界框。这很棘手,因为计算可用角度会增加整个复杂度。
您应该发布一个完整的HTML页面,使用JavaScript内联。 – Fantius
http://stackoverflow.com/questions/2956967/drawing-path-by-bezier-curves – Fantius
这是一个jsfiddle与他的代码:http://jsfiddle.net/EnZX4/ –