本文介紹了如何在Java中使一個(gè)對(duì)象圍繞另一個(gè)移動(dòng)對(duì)象旋轉(zhuǎn)？的處理方法，對(duì)大家解決問(wèn)題具有一定的參考價(jià)值，需要的朋友們下面隨著小編來(lái)一起學(xué)習(xí)吧！
問(wèn)題描述
我對(duì)Java非常陌生，我想編寫一個(gè)簡(jiǎn)單的太陽(yáng)系統(tǒng)，在這個(gè)系統(tǒng)中，月球繞地球公轉(zhuǎn)，地球繞太陽(yáng)公轉(zhuǎn)。
一切都很正常，除了月球不想正確移動(dòng)：/
由于地球偏離月球的初始位置，月球的自轉(zhuǎn)半徑也相應(yīng)增大。同樣，當(dāng)?shù)厍蚋咏虑虻膽T性位置時(shí)，自轉(zhuǎn)半徑也會(huì)減小。
如果初始位置為(0；0)，則它起作用，但月球撞擊太陽(yáng)…
那么我如何才能保持地球和月球之間的距離恒定呢？
我正在使用AffineTransform，以下是我的代碼片段；)
提前謝謝！
Ellipse2D.Double MoonFrame = new Ellipse2D.Double(orbitEarth + orbitMoon - radiusMoon, -radiusMoon, radiusMoon*2, radiusMoon*2);
for (int i = 0; i < 360; i++)
{
theta += Math.PI/30;
AffineTransform TransformMoon = AffineTransform.getRotateInstance(theta,TransformEarth.getTranslateX(),TransformEarth.getTranslateY());
g2d.fill(TransformMond.createTransformedShape(MoonFrame));
}
推薦答案
因此，您的基本問(wèn)題可以歸結(jié)為“如何找到給定角度的圓上的點(diǎn)”…說(shuō)真的，就這么簡(jiǎn)單
基于多個(gè)小時(shí)的谷歌搜索和反復(fù)試驗(yàn)，我基本上使用了以下內(nèi)容，或多或少。
protected Point pointOnCircle() {
double rads = Math.toRadians(orbitAngle - 180); // Make 0 point out to the right...
int fullLength = Math.round((outterRadius));
// Calculate the outter point of the line
int xPosy = Math.round((float) (Math.cos(rads) * fullLength));
int yPosy = Math.round((float) (Math.sin(rads) * fullLength));
return new Point(xPosy, yPosy);
}
剩下的基本上歸結(jié)為正確處理轉(zhuǎn)換的復(fù)合性質(zhì)，
基本上，這將獲取一個(gè)基本Graphics上下文，將平移應(yīng)用到它(地球的位置)，并創(chuàng)建另外兩個(gè)上下文以應(yīng)用其他變換，一個(gè)用于地球，一個(gè)用于月球…
Graphics2D g2d = (Graphics2D) g.create();
int yPos = (getHeight() - size) / 2;
// Transform the offset
g2d.transform(AffineTransform.getTranslateInstance(xPos, yPos));
Graphics2D earthG = (Graphics2D) g2d.create();
// Rotate around the 0x0 point, this becomes the center point
earthG.transform(AffineTransform.getRotateInstance(Math.toRadians(angle)));
// Draw the "earth" around the center point
earthG.drawRect(-(size / 2), -(size / 2), size, size);
earthG.dispose();
// Removes the last transformation
Graphics2D moonG = (Graphics2D) g2d.create();
// Calclate the point on the circle - based on the outterRadius or
// distance from the center point of the earth
Point poc = pointOnCircle();
int moonSize = size / 2;
// This is only a visial guide used to show the position of the earth
//moonG.drawOval(-outterRadius, -outterRadius, outterRadius * 2, outterRadius * 2);
moonG.fillOval(poc.x - (moonSize / 2), poc.y - (moonSize / 2), moonSize, moonSize);
moonG.dispose();
g2d.dispose();
因?yàn)槲抑肋@會(huì)讓你抓狂，這是一個(gè)可行的例子…
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private double angle;
private double orbitAngle;
private int xPos = 0;
private int size = 20;
private int outterRadius = size * 2;
private int delta = 2;
public TestPane() {
new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
xPos += delta;
if (xPos + size >= getWidth()) {
xPos = getWidth() - size;
delta *= -1;
} else if (xPos < 0) {
xPos = 0;
delta *= -1;
}
angle += 4;
orbitAngle -= 2;
repaint();
}
}).start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 200);
}
protected Point pointOnCircle() {
double rads = Math.toRadians(orbitAngle - 180); // Make 0 point out to the right...
int fullLength = Math.round((outterRadius));
// Calculate the outter point of the line
int xPosy = Math.round((float) (Math.cos(rads) * fullLength));
int yPosy = Math.round((float) (Math.sin(rads) * fullLength));
return new Point(xPosy, yPosy);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int yPos = (getHeight() - size) / 2;
// Transform the offset
g2d.transform(AffineTransform.getTranslateInstance(xPos, yPos));
Graphics2D earthG = (Graphics2D) g2d.create();
// Rotate around the 0x0 point, this becomes the center point
earthG.transform(AffineTransform.getRotateInstance(Math.toRadians(angle)));
// Draw the "earth" around the center point
earthG.drawRect(-(size / 2), -(size / 2), size, size);
earthG.dispose();
// Removes the last transformation
Graphics2D moonG = (Graphics2D) g2d.create();
// Calclate the point on the circle - based on the outterRadius or
// distance from the center point of the earth
Point poc = pointOnCircle();
int moonSize = size / 2;
// This is only a visial guide used to show the position of the earth
//moonG.drawOval(-outterRadius, -outterRadius, outterRadius * 2, outterRadius * 2);
moonG.fillOval(poc.x - (moonSize / 2), poc.y - (moonSize / 2), moonSize, moonSize);
moonG.dispose();
g2d.dispose();
}
}
}
這會(huì)使”地球”物體朝一個(gè)方向旋轉(zhuǎn)，然后使月球繞其旋轉(zhuǎn)，朝相反的方向旋轉(zhuǎn)
這篇關(guān)于如何在Java中使一個(gè)對(duì)象圍繞另一個(gè)移動(dòng)對(duì)象旋轉(zhuǎn)？的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，
