我想在画布上绘制看起来随机的曲线斑点，但我好像无法想出算法来实现。我尝试创建随机贝塞尔曲线，就像这样：
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;
}
(这是一种简化方法...我添加了一些约束线条只在画布内部等内容。) 这种方法的问题在于如何让它回到起点，而且不会产生大量尴尬的拐角。是否有人知道更好的算法来实现这个，或者可以想出一个？
编辑：我已经有了一些进展。我重新开始，使用直线（一旦完成这一步，我认为我知道该怎么做才能将它们转换成平滑的贝塞尔曲线）。在绘制每个点之前，它会计算出到前一个点的距离和角度与起点的距离和角度。如果距离小于一定值，就会闭合曲线。否则，可能的角度会随着迭代次数变窄，最大线长是到起点的距离。所以这里有一些代码。
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();
我现在遇到的问题是，形状的轮廓经常交叉，看起来不正常。我能想到的解决方法是跟踪边界框，每个新点应该始终朝着边界框外部前进。这很棘手，因为计算可用角度会增加整个复杂度。