[英]Logarithmic Spiral
So in my programming class we are learning to use draw classes. 因此,在我的编程课程中,我们正在学习使用绘图类。 Basically draw a line and stuff and we did a
y=mx+b
line in class. 基本上绘制一条线和东西,我们在课堂上做了
y=mx+b
线。
I wanted to jump ahead and start doing more crazy mathematical ones! 我想跳过去,开始做更疯狂的数学问题!
I'm having trouble using this one though, which I found on the U of Princeton website. 我在使用这个时遇到了麻烦,我在普林斯顿大学的网站上找到了这个。
public class Spiral {
public static void main(String[] args) {
int N = Integer.parseInt(args[0]); // # sides if decay = 1.0
double decay = Double.parseDouble(args[1]); // decay factor
double angle = 360.0 / N;
double step = Math.sin(Math.toRadians(angle/2.0));
Turtle turtle = new Turtle(0.5, 0.0, angle/2.0);
for (int i = 0; i < 10*N; i++) {
step /= decay;
turtle.goForward(step);
turtle.turnLeft(angle);
}
}
}
import java.awt.Color;
public class Turtle {
private double x, y; // turtle is at (x, y)
private double angle; // facing this many degrees counterclockwise from the x-axis
// start at (x0, y0), facing a0 degrees counterclockwise from the x-axis
public Turtle(double x0, double y0, double a0) {
x = x0;
y = y0;
angle = a0;
}
// rotate orientation delta degrees counterclockwise
public void turnLeft(double delta) {
angle += delta;
}
// move forward the given amount, with the pen down
public void goForward(double step) {
double oldx = x;
double oldy = y;
x += step * Math.cos(Math.toRadians(angle));
y += step * Math.sin(Math.toRadians(angle));
StdDraw.line(oldx, oldy, x, y);
}
// pause t milliseconds
public void pause(int t) {
StdDraw.show(t);
}
public void setPenColor(Color color) {
StdDraw.setPenColor(color);
}
public void setPenRadius(double radius) {
StdDraw.setPenRadius(radius);
}
public void setCanvasSize(int width, int height) {
StdDraw.setCanvasSize(width, height);
}
public void setXscale(double min, double max) {
StdDraw.setXscale(min, max);
}
public void setYscale(double min, double max) {
StdDraw.setYscale(min, max);
}
// sample client for testing
public static void main(String[] args) {
double x0 = 0.5;
double y0 = 0.0;
double a0 = 60.0;
double step = Math.sqrt(3)/2;
Turtle turtle = new Turtle(x0, y0, a0);
turtle.goForward(step);
turtle.turnLeft(120.0);
turtle.goForward(step);
turtle.turnLeft(120.0);
turtle.goForward(step);
turtle.turnLeft(120.0);
}
}
Turtle uses this class: StdDraw
which is just way too many lines of code for me to paste here. Turtle使用这个类:
StdDraw
,这是我要粘贴的代码行太多了。
I keep getting an error when I go to execute spiral: 我去执行螺旋时一直出错:
java.lang.ArrayIndexOutOfBoundsException: 0
at Spiral.main(Spiral.java:4)
Not sure why. 不知道为什么。 Can anyone help me out so I can play around with this?
谁能帮助我,以便我可以解决这个问题?
Did you specify two command-line arguments? 你有没有指定两个命令行参数? It looks like it takes the number of steps and the decay as a parameter and will crash if you don't specify these.
看起来它需要步数和衰减作为参数,如果你没有指定它们就会崩溃。
For example: 例如:
java Spiral 10 1.1
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