我的问题涉及到的各种技术绘制,似乎是写意线:如何绘制手绘的椭圆或圆形?
How do you draw like a Crayon?
具体史蒂夫Hanov张贴了这个优秀的blog entry。
由此我能够使用贝塞尔曲线为徒手线实现漂亮的算法。但是,我坚持如何实现手绘椭圆。理想情况下,我想给它一个矩形作为边界,类似于其他椭圆绘图调用。但是,我希望它看起来很自由。
到目前为止,最好的我想出了这一点:
- (UIBezierPath*) freehandEllipseFromRect:(CGRect) rect {
// freehand ellipses need a lil more height
rect = CGRectMake(rect.origin.x, rect.origin.y-5, rect.size.width, rect.size.height+10);
UIBezierPath* path = [UIBezierPath bezierPath];
CGPoint topMidPoint = CGPointMake(rect.origin.x + (rect.size.width/2), rect.origin.y);
CGPoint bottomMidPoint = CGPointMake(rect.origin.x + (rect.size.width/2), rect.origin.y+rect.size.height);
// random point along bottom quarter of height, cause makes it look better
CGFloat randomY = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * (rect.size.height/4);
CGPoint leftControlPoint = CGPointMake(rect.origin.x-(rect.size.width), rect.origin.y+(rect.size.height-randomY));
// another random y;
randomY = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * (rect.size.height/4);
CGPoint rightControlPoint = CGPointMake(rect.origin.x+(rect.size.width*2), rect.origin.y+(rect.size.height-randomY));
CGFloat overshootValueX = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * 4;
CGFloat overshootValueY = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * 6;
[path moveToPoint:CGPointMake(topMidPoint.x+overshootValueX, topMidPoint.y)];
[path addQuadCurveToPoint:bottomMidPoint controlPoint:leftControlPoint];
// random value to overshoot
overshootValueX = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * 20;
overshootValueY = (((CGFloat) (arc4random() % RAND_MAX)/RAND_MAX)) * 4;
[path addQuadCurveToPoint:CGPointMake(topMidPoint.x-overshootValueX, topMidPoint.y-overshootValueY) controlPoint:rightControlPoint];
return path;
}
结果看起来是这样的:
我不喜欢怎么指出这是在上面,尽管我尝试了所有的尝试,但我无法让它变得更好。另外,我喜欢曲线看起来不那么完美,并且不依赖悬垂物作为唯一的“徒手画”看的部分。我认为2条四线曲线只是错误的路线.....
也许4弧?
任何人有我的另一个解决方案或一些示例代码? (任何语言都可以)