用Java语言来绘制向量场
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昨天晚上看了微分方程课程的视频，了解到了向量场的概念，所以产生了用Java来绘制向量场的想法。目前给出了初步的实现方案，程序有bug，回去继续改。
修改了一会，觉得太麻烦了
下面是代码：
package com.math;import java.awt.BorderLayout;import java.awt.Color;import java.awt.Container;import java.awt.Graphics;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JToggleButton;class PainterPanel extends JPanel { private static final long serialVersionUID = 1L; public PainterPanel() { super(); // 调用父类构造函数 this.setBackground(Color.white); // 设置背景颜色 repaint(); } public void paint(Graphics g) { setSize(1000, 400); g.translate(800, 200); Range range = new Range(-200.0, 20.0); List<Equipotent> el = new ArrayList<Equipotent>(); DirectorField df = new DirectorField(el); addEp1(el, range); addEp2(el, range); addEp3(el, range); addEp4(el, range); df.paint(g); } private void addEp1(List<Equipotent> el, Range range){ Calculater director = new Calculater() { public double getValue(Object[] val) { return 3; }}; Calculater equipotential = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return x+5; } }; Calculater equipotential_1d = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return 1; } }; Calculater equipotential_2d = new Calculater() { public double getValue(Object[] val) {return 0;}}; Equipotent ep = new Equipotent(range, director, equipotential, equipotential_1d, equipotential_2d); el.add(ep); } private void addEp2(List<Equipotent> el, Range range){ Calculater director = new Calculater() { public double getValue(Object[] val) { return 0; }}; Calculater equipotential = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return x+1; } }; Calculater equipotential_1d = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return 1; } }; Calculater equipotential_2d = new Calculater() { public double getValue(Object[] val) {return 0;}}; Equipotent ep = new Equipotent(range, director, equipotential, equipotential_1d, equipotential_2d); el.add(ep); } private void addEp3(List<Equipotent> el, Range range){ Calculater director = new Calculater() { public double getValue(Object[] val) { return 1; }}; Calculater equipotential = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return x; } }; Calculater equipotential_1d = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return 1; } }; Calculater equipotential_2d = new Calculater() { public double getValue(Object[] val) {return 0;}}; Equipotent ep = new Equipotent(range, director, equipotential, equipotential_1d, equipotential_2d); el.add(ep); } private void addEp4(List<Equipotent> el, Range range){ Calculater director = new Calculater() { public double getValue(Object[] val) { return 0; }}; Calculater equipotential = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return x-1; } }; Calculater equipotential_1d = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; return 1; } }; Calculater equipotential_2d = new Calculater() { public double getValue(Object[] val) {return 0;}}; Equipotent ep = new Equipotent(range, director, equipotential, equipotential_1d, equipotential_2d); el.add(ep); }}class Point { public double x, y; public Point(){}; public Point(double _x, double _y) { this.x = _x; this.y = _y; } public String toString() { return "<x:" + x + ", y:" + y + ">"; }}class Range { public double x1, x2; public Range(double _x1, double _x2) { this.x1 = _x1; this.x2 = _x2; } public String toString() { return "<x1:" + x1 + ", x2:" + x2 + ">"; }}interface ICalculater { public double getValue(Object[] val); public double getValue(Object val);}abstract class Calculater implements ICalculater { public double getValue(Object[] val){ return 0.0; } public double getValue(Object val) { return getValue(new Object[] {val}); }}class DirectorField{ List<Equipotent> el; public DirectorField(List<Equipotent> _el) { this.el = _el; } public void paint(Graphics g) { for(Equipotent e : el) { e.paint(g); } }}class Equipotent { Calculater director; Calculater equipotential; // 等势线 Calculater equipotential_1d; // //等势线的向量 Calculater equipotential_2d; Point first, current; double distance = 0.3; // 间隔 double length = 20; // 向量的长度 double e = 0.0001; Range range; ArrayList<Point> pl; int pos = -1; public Equipotent(Range _range, Calculater _director, Calculater _equipotential, Calculater _equipotential_1d, Calculater _equipotential_2d) { this.director = _director; this.equipotential = _equipotential; this.equipotential_1d = _equipotential_1d; this.equipotential_2d = _equipotential_2d; this.range = _range; } public void paint(Graphics g) { try { init(); } catch (Exception e) { e.printStackTrace(); } double px = length / (2 * Math.sqrt(1 + director.getValue(pos))); double py = director.getValue(pos)*px; int rate=100; for (Point p : pl) { p.x = p.x*rate; p.y = p.y*rate; g.drawLine((int) Math.round(p.x - px), (int) Math.round(p.y - py), (int) Math.round(p.x + px), (int) Math.round(p.y + py)); } } private void init() throws Exception { pl = calcPoint(); Collections.sort(pl, new Comparator<Point>() { public int compare(Point o1, Point o2) { return (int) (o1.x - o2.x) * 1000; } }); } private ArrayList<Point> calcPoint() throws Exception { ArrayList<Point> pl = new ArrayList<Point>(); double p; try { p = calcPoint(new Object[]{range.x1}, new Object[]{range.x2}, equipotential_1d, e); ArrayList<Point> pl1 = calcXXX(new Range(range.x1, p), equipotential_1d.getValue(range.x1), equipotential_2d.getValue(range.x1)); ArrayList<Point> pl2 = calcXXX(new Range(p, range.x2), equipotential_1d.getValue(range.x2), equipotential_2d.getValue(range.x2)); pl.addAll(pl1); pl.addAll(pl2); } catch (Exception e) { pl = calcXXX(new Range(range.x1, range.x2), equipotential_1d.getValue(range.x1), equipotential_2d.getValue(range.x1)); } return pl; } private ArrayList<Point> calcXXX(Range range, double e1d, double e2d) { Calculater upper = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; double b = (Double)val[1]; return equipotential.getValue(x) - (equipotential.getValue(b)+Math.sqrt(distance*distance - (x-b)*(x-b))); } }; Calculater down = new Calculater() { public double getValue(Object[] val) { double x = (Double)val[0]; double b = (Double)val[1]; return equipotential.getValue(x) - (equipotential.getValue(b)-Math.sqrt(distance*distance - (x-b)*(x-b))); } }; Calculater calc = e2d > 0 ? upper : down; boolean isLeft = e1d * e2d > 0; ArrayList<Point> pl = new ArrayList<Point>(); try { double b = isLeft ? range.x1 : range.x2; double t = calcTmp(b, isLeft); int i = 0; while (isLeft ? t <= range.x2 : t >= range.x1) { if(i++%30==0) { System.out.print("" + i); } if(isLeft){ if(t<b-distance){ t = b-distance; } }else{ if(t>b+distance){ t = b+distance; } } double x = calcPoint(new Object[]{b, b}, new Object[]{t, b}, calc, this.e); pl.add(new Point(x, equipotential.getValue(x))); b = x; t = calcTmp(b, isLeft); } } catch (Exception e) { e.printStackTrace(); return null; } return pl; } private double calcTmp(double x, boolean isLeft) { double v = equipotential_1d.getValue(x); double t = isLeft ? x + distance / Math.sqrt(1 + v * v) : x - distance / Math.sqrt(1 + v * v); return t; } // 高斯逼近法的变种 private double calcPoint(Object[] params1, Object[] params2, Calculater c, double e) throws Exception { double xa = (Double)params1[0], xb = (Double)params2[0]; double ya = c.getValue(params1); double yb = c.getValue(params2); if(ya<=e) { return xa; }else if(yb<=e) { return xb; } if (!isNeg(ya, yb)) { throw new Exception("there is no result exists"); } Object[] params = new Object[params1.length]; System.arraycopy(params1, 0, params, 0, params1.length); double x = (xa + xb) / 2; params[0] = x; double y = c.getValue(params); int i = 0; while (abs(y) >= e) { if(i%30==0){ System.out.println("hhh"); } if (isNeg(y, ya)) { xb = x; yb = y; } else { xa = x; ya = y; } x = (xa + xb) / 2; params[0] = x; y = c.getValue(params); } return x; } private double abs(double v) { return v > 0 ? v : -v; } private boolean isNeg(double a, double b) { return a * b <= 0; }}public class PainterDemo extends JFrame { JToggleButton[] button = new JToggleButton[3]; // 按钮组 PainterPanel painter = new PainterPanel(); // 绘图面板 public PainterDemo() { super("Java 向量场"); // 调用父类构造函数 Container container = getContentPane(); // 得到窗口容器 container.add(painter, BorderLayout.CENTER); setSize(1000, 600); 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