mygamecanvas.java

来自「3D手机游戏开发实例源代码」· Java 代码 · 共 103 行

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import com.mascotcapsule.micro3d.v3.Util3D;
public class MyGameCanvas extends GameCanvas implements Runnable {
    private boolean isRun; // 根据thread显示有无loop处理的flag
    private int R;          // 外侧的圆的半径
    private int r;          // 内侧的圆的半径
    private int m;          // 内侧圆的中心与描绘点的距离
    private int theta;       // 内侧圆的中心的转动角
    private int cx, cy;      // 外侧圆的中心坐标
    private int preX, preY;  // 1step前的坐标值

    /**
     * MyGameCanvas的constructor
     */
    public MyGameCanvas() {
        super(true);
    }

    /**
     * 初始各个变量，清除画面
     */
    public void reset(int r, int m) {
        cx = getWidth() / 2;
        cy = getHeight() / 2;
        R = getWidth() / 2;
        this.r = r;
        this.m = m;
        theta = 0;
        preX = cx + R - r + m;
        preY = cy;

        // 画面的清除
        Graphics g = getGraphics();
        g.setColor(0xffffff);
        g.fillRect(0, 0, getWidth(), getHeight());
    }
    
    /**
     * thread的开始
     */
    public void start() {
        isRun = true;
        Thread t = new Thread(this);
        t.start();
    }
  
    /**
     * 根据thread执行的方法
     */
    public void run() {
        Graphics g = getGraphics();
        
        while(isRun) {
            tick();
            draw(g);
       
            try {
                Thread.sleep(10); 
            }
            catch (InterruptedException e) {
                stop();
            }
        } 
    }
  
    /**
     * 每经过一定时间的处理
     */
    private void tick() {
        // 更新转动角度
        theta += 50;
    }
   
    /**
     * 描绘的更新
     */
    private void draw(Graphics g) {
        g.setColor(255, 0, 0);
        // 坐标值的计算
        int x = cx + (R - r) * Util3D.cos(theta) / 4096 + 
                m * Util3D.cos(theta - theta * R / r) / 4096;
        int y = cy - (R - r) * Util3D.sin(theta) / 4096 - 
                m * Util3D.sin(theta - theta * R / r) / 4096;

        // 线的描绘
        g.drawLine(preX, preY, x, y);
        
        // 将目前的坐标值保存在preX, preY中
        preX = x;
        preY = y;
        
        flushGraphics();
    }
    
    /**
     * thread的停止
     */
    public void stop() {
        isRun = false;
    }
}