java - 乔格 : my cube rotation speed is not regular

Question

我刚刚在 JOGL 中编写了一个简单的动画:一个 6 色立方体绕 y 轴旋转。但我的动画似乎有一点速度解决方法:有时它会加速，有时它会减慢，尽管我只是使用一个浮点变量调用 glRotate() ，我在每次显示调用时都会增加该变量(我的代码如下)。

• 我的处理器是奔腾双核 t3400
• 我的操作系统是 Xubuntu 11.04 32 位
• 我的显卡是 ATI Radeon HD4330，并且我安装了最新的专有驱动程序:11.6(在 AMD 网站上下载，而不是在 ubuntu 软件管理器上下载)

在 Eclipse EDI(我使用 Indigo 3.7.0)中，这就是我设置用户库的方式:

• 我已经下载了适用于 i586 linux 的 JOGL 2.0 beta 23(从 2011 年 3 月 3 日开始)
• 在用户库中，我导入了以下 jar:newt.all.jar、nativewindow.all.jar、jogl.all.jar、gluegen-rt.jar
• 所有导入的 jar 都链接到未压缩的 jogl 存档的 lib 子文件夹:所有 *.so 文件在哪里

这是我的三个类(class)。

ArcballExperiment.java

package com.gmail.bernabe.laurent.jogl.arcball_experiment;

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.media.opengl.awt.GLCanvas;
import javax.swing.JFrame;

import com.jogamp.opengl.util.Animator;

public class ArcBallExperiment extends JFrame {

    public ArcBallExperiment(){
        setTitle("ArcBall Experimentation");
        setSize(500, 500);
        setLocationRelativeTo(null);

        GLCanvas glCanvas = new GLCanvas();
        TheGLEventListener glEventListener = new TheGLEventListener();
        glCanvas.addGLEventListener(glEventListener);
        add(glCanvas);

        final Animator animator = new Animator(glCanvas);
        addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                animator.stop();
                System.exit(0);
            }


        });

        animator.start();
    }

    public static void main(String[] args) {
        new ArcBallExperiment().setVisible(true);
    }

    private static final long serialVersionUID = 1L;

}

Cube.java:

package com.gmail.bernabe.laurent.jogl.arcball_experiment;

import javax.media.opengl.GL2;

public class Cube {

    /**
     * Draws a cube in a GL2 context
     * @param gl - GL2 - GL2 context
     */
    public static void draw(GL2 gl){
        gl.glBegin(GL2.GL_QUADS);

            // front : blue
            gl.glColor3f(0.0f, 0.0f, 1.0f);
            gl.glVertex3f(-0.5f, +0.5f, +0.5f);
            gl.glVertex3f(-0.5f, -0.5f, +0.5f);
            gl.glVertex3f(+0.5f, -0.5f, +0.5f);
            gl.glVertex3f(+0.5f, +0.5f, +0.5f);

            // back : green
            gl.glColor3f(0.0f, 1.0f, 0.0f);
            gl.glVertex3f(+0.5f, -0.5f, -0.5f);
            gl.glVertex3f(+0.5f, +0.5f, -0.5f);
            gl.glVertex3f(-0.5f, +0.5f, -0.5f);
            gl.glVertex3f(-0.5f, -0.5f, -0.5f);

            // left : red
            gl.glColor3f(1.0f, 0.0f, 0.0f);
            gl.glVertex3f(-0.5f, +0.5f, +0.5f);
            gl.glVertex3f(-0.5f, +0.5f, -0.5f);
            gl.glVertex3f(-0.5f, -0.5f, -0.5f);
            gl.glVertex3f(-0.5f, -0.5f, +0.5f);

            // right : orange
            gl.glColor3f(1.0f, 0.4f, 0.0f);
            gl.glVertex3f(+0.5f, +0.5f, -0.5f);
            gl.glVertex3f(+0.5f, +0.5f, +0.5f);
            gl.glVertex3f(+0.5f, -0.5f, +0.5f);
            gl.glVertex3f(+0.5f, -0.5f, -0.5f);

            // top : white
            gl.glColor3f(1.0f, 1.0f, 1.0f);
            gl.glVertex3f(+0.5f, +0.5f, +0.5f);
            gl.glVertex3f(-0.5f, +0.5f, +0.5f);
            gl.glVertex3f(-0.5f, +0.5f, -0.5f);
            gl.glVertex3f(+0.5f, +0.5f, -0.5f);

            // bottom : yellow
            gl.glColor3f(1.0f, 1.0f, 0.0f);
            gl.glVertex3f(+0.5f, -0.5f, +0.5f);
            gl.glVertex3f(+0.5f, -0.5f, -0.5f);
            gl.glVertex3f(-0.5f, -0.5f, -0.5f);
            gl.glVertex3f(-0.5f, -0.5f, +0.5f);

        gl.glEnd();
    }

}

TheGLEventListener.java:

package com.gmail.bernabe.laurent.jogl.arcball_experiment;

import javax.media.opengl.GL2;
import javax.media.opengl.GLAutoDrawable;
import javax.media.opengl.GLEventListener;
import javax.media.opengl.glu.gl2.GLUgl2;

public class TheGLEventListener implements GLEventListener {

    @Override
    public void display(GLAutoDrawable drawable) {
        GL2 gl = drawable.getGL().getGL2();
        gl.glClear(GL2.GL_COLOR_BUFFER_BIT | GL2.GL_DEPTH_BUFFER_BIT);
        gl.glLoadIdentity();

        glu.gluLookAt(
                0f, 0f, 3f,
                0f, 0f, 0f,
                0f, 1f, 0f
        );

        gl.glRotatef(rotationAngle, 0f, 1f, 0f);
        Cube.draw(gl);

        rotationAngle += 0.3f;
        if (rotationAngle >= 360f)
            rotationAngle %= 360f;
    }

    @Override
    public void dispose(GLAutoDrawable drawable) {
        // TODO Auto-generated method stub

    }

    @Override
    public void init(GLAutoDrawable drawable) {
        GL2 gl = drawable.getGL().getGL2();
        gl.glEnable(GL2.GL_DEPTH_TEST);
        gl.glDepthFunc(GL2.GL_LEQUAL);
        gl.glClearDepthf(1.0f);
    }

    @Override
    public void reshape(GLAutoDrawable drawable, int x, int y, int width,
            int height) {
        GL2 gl = drawable.getGL().getGL2();
        gl.glViewport(x, y, width, height);

        gl.glMatrixMode(GL2.GL_PROJECTION);
        gl.glLoadIdentity();
        glu.gluPerspective(60.0f, (float) width/height, 1f, 10f);

        gl.glMatrixMode(GL2.GL_MODELVIEW);
    }

    private GLUgl2 glu = new GLUgl2();
    private float rotationAngle = 0f;

}

我认为这可能是因为我在为 JOGL eclipse 项目制作的用户库中导入了不兼容的 jar，但我不确定。

提前致谢

(ArcBall 实验的标题似乎不太恰当，但事实是这样的:这个立方体旋转只是我在进行 ArcBall 实现之前再次记住 JOGL 编程的一个阶段。)

Answer 1

终于解决了这个问题:) 我将动画师实例更改为 FPSAnimator 而不是 Animator，以保持恒定的 FPS。只有一类需要更新: ArcBallExperiment.java

package com.gmail.bernabe.laurent.jogl.arcball_experiment;

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.media.opengl.awt.GLCanvas;
import javax.swing.JFrame;

import com.jogamp.opengl.util.FPSAnimator;

public class ArcBallExperiment extends JFrame {

    public ArcBallExperiment(){
        setTitle("ArcBall Experimentation");
        setSize(500, 500);
        setLocationRelativeTo(null);

        GLCanvas glCanvas = new GLCanvas();
        TheGLEventListener glEventListener = new TheGLEventListener();
        glCanvas.addGLEventListener(glEventListener);
        add(glCanvas);

        /*
         *  Here I limit the FPS to a quite lower value than default,
         *  thanks to the FPSAnimator class : 180 FPS here.
         *  That way, cube rotation speed will really be constant
         */
        final FPSAnimator animator = new FPSAnimator(glCanvas, 180);
        addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                animator.stop();
                System.exit(0);
            }


        });

        animator.start();
    }

    public static void main(String[] args) {
        new ArcBallExperiment().setVisible(true);
    }

    private static final long serialVersionUID = 1L;

}