如何使用gnuplot在对角线中绘制矩

Question

我在gnuplot中绘制了一个矩形，但我希望它出现在对角线中

set object 1 rect from 53.1035,126.27 to 133.104,146.27

I have :
     _____
    |     |
    |_____|

I want :
        _____
       /    /
      /____/

Answer 1

据我所知，还没有（尚未）绘制旋转矩形的简单选择。
正如@Tomsolid已经指出的那样，在一般情况下，您可以“手动”绘制多边形。

因此，如果要旋转矩形，则必须将 a = atan（dy/dx），

但是请记住，矩形只会以矩形和相同的比例出现。如果X轴和Y轴具有相同的缩放因子。您可以通过设置大小比例-1 （检查帮助> size ）来执行此功能。
如果X和Y轴没有相同的缩放因素，则还可以保留旋转矩形的（视觉）比例，但这将需要更多的额外努力。

编辑：脚本更改为更通用的解决方案。旋转中心可以定义。
此外，旋转角坐标的功能（ x1r（n），y1r（n），... ）实际上不是 n 的函数，而是这样的函数函数将在呼叫时采用 x0，y0，x1，y1 的当前值。

脚本：

### draw a rotated rectangle
reset session

x0 = 53.1035
y0 = 126.27
x1 = 133.104
y1 = 146.27

set obj 1 rect from x0,y0 to x1,y1 
set obj 1 fs empty border rgb "red"

set size ratio -1

set angle degrees
a  = 45     # rotation angle
xc = x0     # rotation around bottom...
yc = y0     # ...left corner x0,y0

# functions for rotation of rectangle corner coordinates
x1r(n) = xc+(x0-xc)*cos(a)-(y0-yc)*sin(a)
y1r(n) = yc+(x0-xc)*sin(a)+(y0-yc)*cos(a)
x2r(n) = xc+(x1-xc)*cos(a)-(y0-yc)*sin(a)
y2r(n) = yc+(x1-xc)*sin(a)+(y0-yc)*cos(a)
x3r(n) = xc+(x1-xc)*cos(a)-(y1-yc)*sin(a)
y3r(n) = yc+(x1-xc)*sin(a)+(y1-yc)*cos(a)
x4r(n) = xc+(x0-xc)*cos(a)-(y1-yc)*sin(a)
y4r(n) = yc+(x0-xc)*sin(a)+(y1-yc)*cos(a)

set obj 2 polygon from x1r(0),y1r(0) to x2r(0),y2r(0) to x3r(0),y3r(0) to x4r(0),y4r(0) to x1r(0),y1r(0)
set obj 2 fs empty border rgb "blue"

a = atan(real(y1-y0)/(x1-x0))       # real() to avoid potential integer division
xc = (x0+x1)/2.                     # rotation around...
yc = (y0+y1)/2.                     # ...rectangle center

set obj 3 polygon from x1r(0),y1r(0) to x2r(0),y2r(0) to x3r(0),y3r(0) to x4r(0),y4r(0) to x1r(0),y1r(0)
set obj 3 fs empty border rgb "green"

set xrange [0:150]
set yrange [100:200]
set key top left

plot NaN notitle, \
     keyentry w l lc "red" ti "original rectangle", \
     keyentry w l lc "blue" ti "rotated by 45° around x0,y0", \
     keyentry w l lc "green" ti "rotated by diagonal around center"
### end of script

结果：

Answer 2

您可以使用

set object polygon from <position> to <position> to <position>