圆弧，切饼，在 svgwrite 中

Question

有没有人有在 svgwrite (python) 中完成的弧形切片（奶酪切片或吃豆人）的工作示例，我尝试过此操作，试图获得从 (100,100) 开始的西北象限，但得到一个奇怪的形状：

w = dwg.path(d="M 100,50 A 50,50 0 0 1 50,100 l 0,50 z", fill="#ffff00", stroke='none')

我查看了 inkscape 生成的 svg 的实际输出，这是等效的 xml：

<path
   d="M 100,50 A 50,50 0 0 1 50,100 l 0,50 z"
   style="fill:#ffff00;fill-opacity:1;fill-rule:nonzero;stroke:none"
   sodipodi:type="arc"
   sodipodi:cx="100"
   sodipodi:cy="100"
   sodipodi:rx="50"
   sodipodi:ry="50"
   sodipodi:start="4.71"
   sodipodi:end="3.14"
    />

但我无法 a) 让 svgwrite 生成这个 b) 如果我获取 svgwrite 生成的 svg 文件并将这段代码替换到其中，它没有任何效果，可能是因为 sodipodi 命令是 inkscape 特定的。

有人有这方面的工作示例吗？

Answer 1

阅读更多文档并查看示例下的链接后确定

http://www.w3.org/TR/SVG11/paths.html#PathData

这是 svgwrite 中工作楔形的示例

    w = dwg.path(d="M0,0 v-150 a150,150 0 0,0 -150,150 z",
             fill="#00ff00", 
             stroke="none",
            )

这给了我一个西北象限。

我想将圆分成 10 度角，所以我编写了以下代码：

start_x = 250
start_y = 300
radius = 100
for i in range(36):
    degree0 = 0 + i*10
    degree1 = 10 + i*10
    radians0 = math.radians(degree0)
    radians1 = math.radians(degree1)
    dx0 = radius*(math.sin(radians0))
    dy0 = radius*(math.cos(radians0))
    dx1 = radius*(math.sin(radians1))
    dy1 = radius*(math.cos(radians1))

    m0 = dy0 
    n0 = -dx0 
    m1 = -dy0 + dy1 
    n1 = dx0 - dx1 

    w = dwg.path(d="M {0},{1} l {2},{3} a {4},{4} 0 0,0 {5},{6} z".format(start_x, start_y, m0, n0, radius, m1, n1),
             fill="#00ff00", 
             stroke="none",
            )
    elem.append(w)

它明确地给了我所有这些削减，如果你想运行三角学，也可以明确地使用它们。这是针对以 (250,300) 为中心、半径为 100 的线段。

0   : d=" M 250,300 l 100.0,-0.0 a 100,100 0 0,0 -1.5192246987791975,-17.364817766693033 z "
10  : d=" M 250,300 l 98.4807753012208,-17.364817766693033 a 100,100 0 0,0 -4.511513222629958,-16.837196565873835 z "
20  : d=" M 250,300 l 93.96926207859084,-34.20201433256687 a 100,100 0 0,0 -7.366721700146968,-15.797985667433124 z "
30  : d=" M 250,300 l 86.60254037844388,-49.99999999999999 a 100,100 0 0,0 -9.998096066546069,-14.278760968653934 z "
40  : d=" M 250,300 l 76.60444431189781,-64.27876096865393 a 100,100 0 0,0 -12.325683343243867,-12.325683343243881 z "
50  : d=" M 250,300 l 64.27876096865394,-76.60444431189781 a 100,100 0 0,0 -14.278760968653927,-9.998096066546054 z "
60  : d=" M 250,300 l 50.000000000000014,-86.60254037844386 a 100,100 0 0,0 -15.797985667433132,-7.366721700146968 z "
70  : d=" M 250,300 l 34.20201433256688,-93.96926207859083 a 100,100 0 0,0 -16.837196565873843,-4.511513222629972 z "
80  : d=" M 250,300 l 17.36481776669304,-98.4807753012208 a 100,100 0 0,0 -17.364817766693033,-1.5192246987791975 z "
90  : d=" M 250,300 l 6.123233995736766e-15,-100.0 a 100,100 0 0,0 -17.364817766693037,1.5192246987791975 z "
100 : d=" M 250,300 l -17.36481776669303,-98.4807753012208 a 100,100 0 0,0 -16.83719656587384,4.511513222629958 z "
110 : d=" M 250,300 l -34.20201433256687,-93.96926207859084 a 100,100 0 0,0 -15.79798566743311,7.366721700146968 z "
120 : d=" M 250,300 l -49.99999999999998,-86.60254037844388 a 100,100 0 0,0 -14.278760968653962,9.998096066546069 z "
130 : d=" M 250,300 l -64.27876096865394,-76.60444431189781 a 100,100 0 0,0 -12.325683343243853,12.325683343243867 z "
140 : d=" M 250,300 l -76.6044443118978,-64.27876096865394 a 100,100 0 0,0 -9.998096066546083,14.278760968653948 z "
150 : d=" M 250,300 l -86.60254037844388,-49.99999999999999 a 100,100 0 0,0 -7.366721700146954,15.797985667433103 z "
160 : d=" M 250,300 l -93.96926207859083,-34.20201433256689 a 100,100 0 0,0 -4.511513222629972,16.837196565873864 z "
170 : d=" M 250,300 l -98.4807753012208,-17.364817766693026 a 100,100 0 0,0 -1.5192246987791975,17.364817766693015 z "
180 : d=" M 250,300 l -100.0,-1.2246467991473532e-14 a 100,100 0 0,0 1.5192246987791975,17.364817766693058 z "
190 : d=" M 250,300 l -98.4807753012208,17.364817766693047 a 100,100 0 0,0 4.511513222629958,16.83719656587382 z "
200 : d=" M 250,300 l -93.96926207859084,34.20201433256687 a 100,100 0 0,0 7.366721700146982,15.797985667433146 z "
210 : d=" M 250,300 l -86.60254037844386,50.000000000000014 a 100,100 0 0,0 9.998096066546054,14.278760968653913 z "
220 : d=" M 250,300 l -76.60444431189781,64.27876096865393 a 100,100 0 0,0 12.325683343243867,12.325683343243867 z "
230 : d=" M 250,300 l -64.27876096865394,76.6044443118978 a 100,100 0 0,0 14.278760968653899,9.998096066546054 z "
240 : d=" M 250,300 l -50.00000000000004,86.60254037844385 a 100,100 0 0,0 15.797985667433188,7.3667217001469965 z "
250 : d=" M 250,300 l -34.202014332566854,93.96926207859084 a 100,100 0 0,0 16.83719656587382,4.511513222629958 z "
260 : d=" M 250,300 l -17.364817766693033,98.4807753012208 a 100,100 0 0,0 17.364817766693015,1.5192246987791975 z "
270 : d=" M 250,300 l -1.8369701987210297e-14,100.0 a 100,100 0 0,0 17.364817766693015,-1.5192246987791833 z "
280 : d=" M 250,300 l 17.364817766692997,98.48077530122082 a 100,100 0 0,0 16.8371965658739,-4.511513222629986 z "
290 : d=" M 250,300 l 34.2020143325669,93.96926207859083 a 100,100 0 0,0 15.797985667433117,-7.366721700146968 z "
300 : d=" M 250,300 l 50.000000000000014,86.60254037844386 a 100,100 0 0,0 14.278760968653913,-9.998096066546054 z "
310 : d=" M 250,300 l 64.27876096865393,76.60444431189781 a 100,100 0 0,0 12.325683343243853,-12.325683343243853 z "
320 : d=" M 250,300 l 76.60444431189778,64.27876096865396 a 100,100 0 0,0 9.998096066546054,-14.278760968653913 z "
330 : d=" M 250,300 l 86.60254037844383,50.00000000000004 a 100,100 0 0,0 7.366721700147011,-15.797985667433181 z "
340 : d=" M 250,300 l 93.96926207859084,34.20201433256686 a 100,100 0 0,0 4.511513222629958,-16.83719656587382 z "
350 : d=" M 250,300 l 98.4807753012208,17.36481776669304 a 100,100 0 0,0 1.5192246987791975,-17.364817766693015 z "