Objective-C中的贝塞尔曲线算法 [英] Bezier curve algorithm in objective-c
问题描述
比我聪明的人可以看看这个吗?我正在尝试实施Bezier曲线算法,我在目标-此处 c.
Can someone smarter than me take a look at this. I'm trying to implement a Bezier curve algorithm I found here in objective-c.
输出错误.我想我正确地转换了代码,所以原来的代码是错误的或不是这样使用的……如果我使用内置的NSBezierPath
,则曲线看起来不错,但我不能使用内置的NSBezierPath
The output is way wrong. I think I converted the code correctly so either the original was wrong or was not ment to be used like this... If I use the built in NSBezierPath
the curve looks great but I can't use the built in NSBezierPath
.
NSBezierPath *bezierPath = [[NSBezierPath alloc] init];
[bezierPath setLineWidth:1.0f];
[bezierPath moveToPoint:NSMakePoint(x1, y1)];
[bezierPath curveToPoint:NSMakePoint(x4, y4) controlPoint1:NSMakePoint(x2, y2) controlPoint2:NSMakePoint(x3, y3)];
我的代码试图绘制贝塞尔曲线
- (void)drawBezierFrom:(NSPoint)from to:(NSPoint)to controlA:(NSPoint)a controlB:(NSPoint)b color:(NSUInteger)color
{
float qx, qy;
float q1, q2, q3, q4;
int plotx, ploty;
float t = 0.0;
while (t <= 1)
{
q1 = t*t*t*-1 + t*t*3 + t*-3 + 1;
q2 = t*t*t*3 + t*t*-6 + t*3;
q3 = t*t*t*-3 + t*t*3;
q4 = t*t*t;
qx = q1*from.x + q2*to.x * q3*a.x + q4*b.x;
qy = q1*from.y + q2*to.y * q3*a.y + q4*b.y;
plotx = round(qx);
ploty = round(qy);
[self drawPixelColor:color atX:plotx y:ploty];
t = t + 0.003;
}
}
编辑
请参见 objective-c中的贝塞尔曲线算法需要调整获取完整的功能贝塞尔曲线方法.
Edit
See Bezier curve algorithm in objective-c needs a tweak for a completed functional Bezier Curve method.
推荐答案
我在我的xy绘图仪上使用了这个Bezier函数,发现"to"有一个小错误.
需要切换to.x
to.y
和b.x
b.y
,以便笔在from
处开始并在to
处结束.
I used this Bezier function with my xy plotter and found a small error with the 'to'.
The to.x
to.y
and b.x
b.y
need to be switched so that the pen starts at from
and ends at to
.
qx = q1*from.x + q2*a.x + q3*b.x + q4*to.x;
qy = q1*from.y + q2*a.y + q3*b.y + q4*to.y;
这篇关于Objective-C中的贝塞尔曲线算法的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!