如何使用 gnuplot 绘制一系列带 RGBA 填充的三角形

[nealot]

输入数据的格式大概是这样的 (可调整), 其中 rgba 是三角形的填充颜色

x1 y1 x2 y2 x3 y3 rgba # 1st triangle
x1 y1 x2 y2 x3 y3 rgba # 2nd triangle
...

希望有一个现成的工具 (不限于 gnuplot) 能把这些三角形依次画出来，实现类似图层叠加的效果，输出到文件

在等到答案前我已经用其它方法手动实现了，C# 写这种程序真顺手啊

using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        // check argument
        if (args.Length != 1) {
            Console.WriteLine("Usage: ImagePainter {filename}");
            return;
        }
        string filename = args[0];

        // open data file
        StreamReader file = new StreamReader(filename);

        // init bitmap
        Bitmap bitmap = new Bitmap(800, 800);
        Graphics g = Graphics.FromImage(bitmap);

        // read file
        string line;

        // draw triangles
        while ((line = file.ReadLine()) != null) {
            string[] fields = line.Trim().Split('\t');
            double x1 = Convert.ToDouble(fields[0]);
            double y1 = Convert.ToDouble(fields[1]);
            double x2 = Convert.ToDouble(fields[2]);
            double y2 = Convert.ToDouble(fields[3]);
            double x3 = Convert.ToDouble(fields[4]);
            double y3 = Convert.ToDouble(fields[5]);
            double red = Convert.ToDouble(fields[6]);
            double green = Convert.ToDouble(fields[7]);
            double blue = Convert.ToDouble(fields[8]);
            double alpha = Convert.ToDouble(fields[9]);

            PointF[] points = {
                new PointF(800 * (float)x1, 800 * (float)y1),
                new PointF(800 * (float)x2, 800 * (float)y2),
                new PointF(800 * (float)x3, 800 * (float)y3)
            };
            Color color = Color.FromArgb(
                (int)(255 * alpha),
                (int)(255 * red),
                (int)(255 * green),
                (int)(255 * blue);
            g.FillPolygon(new SolidBrush(color), points);
        }

        bitmap.Save(filename + ".bmp");
    }
}