使用 gnuplot 绘制三角形网格

Question

经常需要使用gnuplot绘制三角网格。

我目前看到的唯一方法是使用 with lines 选项制作“线框”，并在每个方面的闭合线链之间添加双换行符（第一点和最后一点相同）：

$wireframe <<EOD
 0  1 1 p1
 1 -1 1 p2
-1 -1 1 p3
 0  1 1 


 2  1 0 p4
 0  1 1 
 1 -1 1 
 2  1 0 


 0 -2 0 p5
 1 -1 1 
-1 -1 1 
 0 -2 0 


-2  1 0 p6
-1 -1 1 
 0  1 1 
-2  1 0 
EOD
splot '$wireframe' with lines notitle, '' with labels offset character 0, character 1 notitle

这是 4 个三角形：1 个位于中心（p1、p2、p3），3 个与腿相邻。

定义网格的某些方法有很多重复之处。有时将网格定义为三角带或三角扇更合适。

另一个问题是用某种颜色填充 3D 三角形的内部。目前我只能为不同的链线使用不同的颜色（来自调色板）绘制线框。但它们重叠。

说，我想画二十面体。它是封闭的实体，由三角形面约束。

Answer 1

set terminal wxt size 800,600

#set title "Graph Title"
#set xlabel "X"
#set ylabel "Y"
#set zlabel "Z"

# sets background color
set object 1 rectangle from screen -0.1,-0.1 to screen 1.1,1.1 fillcolor rgb "#ffffff" behind

# allows rendering of polygons with hidden line removal
set hidden3d back offset 0 trianglepattern 3 undefined 1 altdiagonal bentover

# displays borders 0x7F = 0b1111111
set border 0x7F linecolor rgb "#555555"

# displays the x, y and z axis
set xzeroaxis linewidth 0.5 linetype 1
set yzeroaxis linewidth 0.5 linetype 2
set zzeroaxis linewidth 0.5 linetype 3

# displays the x, y and z grid
set grid xtics linecolor rgb "#888888" linewidth 0.2 linetype 9
set grid ytics linecolor rgb "#888888" linewidth 0.2 linetype 9
set grid ztics linecolor rgb "#888888" linewidth 0.2 linetype 9

# moves the x, y grid to 0
set xyplane at 0

# makes the x, y, and z axis proportional
set view equal xyz

# sets the axis range
set xrange [-10:10]
set yrange [-10:10]
set zrange [-10:10]

# moves the key out of the graph
set key outside vertical bottom right

# hides the key
set key off

splot\
"ico.dat" title "ico" with lines linewidth 2.1 linecolor rgb "#88FF88"

ico.dat：

-1.381925 -4.253200 -2.236075
0.000000 0.000000 -5.000000

3.618000 -2.628600 -2.236075
3.618000 -2.628600 -2.236075


3.618000 -2.628600 -2.236075
0.000000 0.000000 -5.000000

3.618000 2.628600 -2.236075
3.618000 2.628600 -2.236075


-4.472125 0.000000 -2.236075
0.000000 0.000000 -5.000000

-1.381925 -4.253200 -2.236075
-1.381925 -4.253200 -2.236075


-1.381925 4.253200 -2.236075
0.000000 0.000000 -5.000000

-4.472125 0.000000 -2.236075
-4.472125 0.000000 -2.236075


3.618000 2.628600 -2.236075
0.000000 0.000000 -5.000000

-1.381925 4.253200 -2.236075
-1.381925 4.253200 -2.236075


3.618000 -2.628600 -2.236075
3.618000 2.628600 -2.236075

4.472125 0.000000 2.236075
4.472125 0.000000 2.236075


-1.381925 -4.253200 -2.236075
3.618000 -2.628600 -2.236075

1.381925 -4.253200 2.236075
1.381925 -4.253200 2.236075


-4.472125 0.000000 -2.236075
-1.381925 -4.253200 -2.236075

-3.618000 -2.628600 2.236075
-3.618000 -2.628600 2.236075


-1.381925 4.253200 -2.236075
-4.472125 0.000000 -2.236075

-3.618000 2.628600 2.236075
-3.618000 2.628600 2.236075


3.618000 2.628600 -2.236075
-1.381925 4.253200 -2.236075

1.381925 4.253200 2.236075
1.381925 4.253200 2.236075


4.472125 0.000000 2.236075
1.381925 -4.253200 2.236075

3.618000 -2.628600 -2.236075
3.618000 -2.628600 -2.236075


1.381925 -4.253200 2.236075
-3.618000 -2.628600 2.236075

-1.381925 -4.253200 -2.236075
-1.381925 -4.253200 -2.236075


-3.618000 -2.628600 2.236075
-3.618000 2.628600 2.236075

-4.472125 0.000000 -2.236075
-4.472125 0.000000 -2.236075


-3.618000 2.628600 2.236075
1.381925 4.253200 2.236075

-1.381925 4.253200 -2.236075
-1.381925 4.253200 -2.236075


1.381925 4.253200 2.236075
4.472125 0.000000 2.236075

3.618000 2.628600 -2.236075
3.618000 2.628600 -2.236075


1.381925 -4.253200 2.236075
4.472125 0.000000 2.236075

0.000000 0.000000 5.000000
0.000000 0.000000 5.000000


-3.618000 -2.628600 2.236075
1.381925 -4.253200 2.236075

0.000000 0.000000 5.000000
0.000000 0.000000 5.000000


-3.618000 2.628600 2.236075
-3.618000 -2.628600 2.236075

0.000000 0.000000 5.000000
0.000000 0.000000 5.000000


1.381925 4.253200 2.236075
-3.618000 2.628600 2.236075

0.000000 0.000000 5.000000
0.000000 0.000000 5.000000


4.472125 0.000000 2.236075
1.381925 4.253200 2.236075

0.000000 0.000000 5.000000
0.000000 0.000000 5.000000

由 blender 和 python 脚本生成：
https://github.com/lowlevel86/blender-to-gnuplot

Answer 2

一种解决方法是编写一个 gawk/Python 脚本，该脚本将解析构面的定义并生成一个 Gnuplot 脚本，其中将手动将构面绘制为多边形：

set xr [0:1]
set yr [0:1]
set zr [0:1]

#generate the polygons
set object polygon from 0,0,0 to 1,0,0 to 1,1,0 to 0,1,0 to 0,0,0 fc rgb "cyan" fillstyle solid 1.0 border lt -1
set object polygon from 1,0,0 to 1,1,0 to 1,1,1 to 1,0,1 to 1,0,0 fc rgb "cyan" fillstyle solid 1.0 border lt -1

#do not plot anything
splot 1/0