menucanvas.java

在J2ME下面实现3D菜单,可以用于游戏开发(需要jsr184支持)

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import javax.microedition.m3g.*;
import javax.microedition.m3g.Camera;

public class MenuCanvas extends GameCanvas implements Runnable{
    private Alert alert; // display info text on the screen

    private Graphics3D g3d;
    private World world;
    private Mesh mesh;
    private Camera camera;

    // The appearances is used for each menu texture. 
    private Appearance appearance1;
    private Appearance appearance2;
    private Appearance appearance3;
    private Appearance appearance4;

    private final int WIDTH, HEIGHT; // the canvas size

    // the menue options
    private String []menu = new String[] {"Play game", "High scores...", "About...", "Help...", "Options...", "Quit"};
    private final int MENU_SIZE = menu.length;
    private Texture2D []texMenu = new Texture2D[MENU_SIZE];

    private int index = 0; // menu index
    private int face = 0; // cube face 0-3

    // the current angle of the menu.
    private int menu_angle = 0;
    private int menu_rot = 0; // -1 or 1

    private MIDlet midlet;
    
    public MenuCanvas(MIDlet m){
        super(false);
        
        midlet = m;
        
        setFullScreenMode(true);
        
        WIDTH = getWidth();
        HEIGHT = getHeight();

        g3d = Graphics3D.getInstance();

        world = new World();
        camera = new Camera();
        camera.setPerspective(60.0f, (float)WIDTH/(float)HEIGHT, 0.1f, 50.0f);
        world.addChild(camera);
        world.setActiveCamera(camera);

        mesh = MeshCreate.createItem(); // create the menu mesh
        mesh.translate(0.0f, -3.0f, -11.0f); // menu position
        world.addChild(mesh);
        appearance1 = mesh.getAppearance(0); // front
        appearance2 = mesh.getAppearance(1); // back
        appearance3 = mesh.getAppearance(4); // top
        appearance4 = mesh.getAppearance(5); // bottom
        
        // generate the menu textures to use.
        createTextures();
        
        new Thread(this).start();
    }

    /*
     * Create one texture for each option in the nenu.
     */
    private void createTextures(){

        Image image;
        try{
            for(int i=0; i<menu.length; i++){
                image = createMenuImage(menu[i]); // create an image from text
                texMenu[i] = new Texture2D(new Image2D(Image2D.RGB, image));
                texMenu[i].setFiltering(Texture2D.FILTER_LINEAR, Texture2D.FILTER_LINEAR);
                texMenu[i].setWrapping(Texture2D.WRAP_CLAMP, Texture2D.WRAP_CLAMP);
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        
        appearance1.setTexture(0, texMenu[0]);
        appearance3.setTexture(0, texMenu[1]);
        appearance4.setTexture(0, texMenu[5]);
        
    }
    
    /*
     * Create an image from the text sent to the method
     */
    private Image createMenuImage(String imgStr){
        int bgColor = 0xFFFFFF;
        int fgColor = 0x00;
        String menu;
        Font f = Font.getDefaultFont();
        Image image = null;
        
        try{
            Image bgImage = Image.createImage("/menubg.png");
            
            image = Image.createImage(128, 32);
            Graphics g = image.getGraphics();
            g.setFont(f);
            g.setColor(bgColor);
            g.fillRect(0, 0, image.getWidth(), image.getHeight());
            g.drawImage(bgImage, 0, 0, 0);
            g.setColor(fgColor);
            menu = imgStr;
            
            g.drawString(menu, image.getWidth()/2 - f.stringWidth(menu)/2, 7, Graphics.TOP | Graphics.LEFT);
        }catch(Exception e){
            e.printStackTrace();
        }

        return image;
    }
    
    /*
    * when the menu is rotating the textures on the cube is changing.
    */
    private void changeTextures(){
        int front, top, bottom;
        front = top = bottom = 0;
        Appearance f,t,b;

        f = appearance1;
        t = appearance3;
        b = appearance4;
        
        // keep track of which appearance is actually facing the screen.
        switch(face){
            case 0:
                f = appearance1;
                t = appearance3;
                b = appearance4;
                break;
            case 1:
                f = appearance3;
                t = appearance2;
                b = appearance1;
                break;
            case 2:
                f = appearance2;
                t = appearance4;
                b = appearance3;
                break;
            case 3:
                f = appearance4;
                t = appearance1;
                b = appearance2;
                break;
        }

        front = index;
        top = index<MENU_SIZE-1?index+1:0;
        bottom = index > 0? index-1:MENU_SIZE-1;
        
        // set the texture for an appearance
        f.setTexture(0, texMenu[front]);
        t.setTexture(0, texMenu[top]);
        b.setTexture(0, texMenu[bottom]);
    }

    /*
     * The rendering method.
     */
    public void draw3D(Graphics g){
        try{
            g3d.bindTarget(g);
            g3d.render(world);
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            g3d.releaseTarget();
        }
    }
    
    /*
     * Used when the fire button is pressed
     */
    private void menuSelect(){
        switch(index){
            case 0:
                // display the text on the screen.
                alert.setText("Start Game");
                alert.start();
                break;
            case 1:
                alert.setText("High scores");
                alert.start();
                break;
            case 2:
                alert.setText("About");
                alert.start();
                break;
            case 3:
                alert.setText("Help");
                alert.start();
                break;
            case 4:
                alert.setText("Options");
                alert.start();
                break;
            case 5: // Exit
                midlet.notifyDestroyed();
                break;
        }
    }

    public void keyPressed(int key){
        System.out.println(key);
        switch(key){
            case -1: // UP
                if(menu_rot==0){
                    index = index > 0?index-1:MENU_SIZE-1;
                    face = face > 0 ? face-1:3;
                    menu_rot = -3;
                }
                break;
            case -2: // DOWN
                if(menu_rot==0){
                    index = index < MENU_SIZE-1 ? index+1:0;
                    face = face <3 ? face+1:0;
                    menu_rot = 3;
                }
                break;
            case -5: // FIRE
                menuSelect();
                break;
        }
        System.out.println("index:" + index);
    }

    public void keyRepeated(int key){
        keyPressed(key);
    }

    public void run(){
        Graphics graphics = this.getGraphics();
        alert = new Alert();
        while(true){

            // rotate the menu.
            if(menu_rot != 0){
                menu_angle += menu_rot;
                mesh.postRotate(menu_rot, 1.0f, 0.0f, 0.0f);
                if(menu_angle%90==0){
                    menu_rot=0;
                    changeTextures();
                }
            }

            draw3D(graphics);
            
            // draw the alert text
            if(alert.isStarted()){
                alert.draw(graphics);
            }

//            scroller.draw(graphics);

            flushGraphics();
            try{
                Thread.sleep(10);
            }catch(Exception e){}
        }
        
    }
    
}