java - Android OpenGL ES…为什么本教程始终可以正确渲染，而我的版本却随机显示不正确？

我遵循的是位于insanitydesign.com的教程集，该教程集是OpenGL上NeHe教程的Android端口。我在理解为什么教程版本在任何时候都能始终正确渲染而我的修改版本随机完全完全不正确渲染时遇到了很多问题。有时，该问题在程序加载时立即显现出来，但是有时我必须在出现屏幕之前旋转屏幕。您可以下载一个包含screengrabs的zip文件，我将屏幕旋转了12次from filedropper。如您所见，三角形通常会渲染，但有时看起来会完全扭曲和弄脏。 Here is a link to my entire Eclipse project如果您很好奇。

我怀疑问题出在我的Shape.draw（）方法中，但我不确定。

我相信，这是相关的代码：

GLRenderer.java

    private Shape shape;

public GLRenderer(){
    Log.i(this.toString(),"ctor");
    shape = Shape.makeTriangle();
}

@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    speedPerSecond = SystemClock.uptimeMillis();
    Log.d(this.toString(), ".onSurfaceCreated");

    gl.glShadeModel(GL10.GL_SMOOTH);



    gl.glClearColor(1.0f, 0.0f, 0.0f, 0.5f);


    gl.glClearDepthf(1.0f);                     //Depth Buffer Setup



    gl.glEnable(GL10.GL_DEPTH_TEST);            //Enables Depth Testing
    gl.glDepthFunc(GL10.GL_LEQUAL);             //The Type Of Depth Testing To Do

    //Really Nice Perspective Calculations
    gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);

}

@Override
public void onDrawFrame(GL10 gl) {

    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    gl.glLoadIdentity();

    shape.setX(0.0f);
    shape.setY(0.0f);
    shape.setZ(-6.0f);
    shape.draw(gl);
}

@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
    if(height == 0){
        height = 1;
    }
    gl.glViewport(0, 0, width, height);
    gl.glMatrixMode(GL10.GL_PROJECTION);
    gl.glLoadIdentity();


    GLU.gluPerspective(gl, 45.0f, (float)width / (float)height, 0.1f, 50.0f);


    gl.glMatrixMode(GL10.GL_MODELVIEW);
    gl.glLoadIdentity();


}

Shape.java
包com.smashing.test;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.opengles.GL10;

import android.util.Log;

public class Shape implements IGLShape {

    public float getX(){
        return x;
    }

    public float getY(){
        return y;
    }

    public float getZ(){
        return z;
    }

    public void setX(float pX){
        x = pX;
    }

    public void setY(float pY){
        y = pY;
    }

    public void setZ(float pZ){
        z = pZ;
    }



    public static Shape makeTriangle(){
        Shape s = new Shape();
                /*
                 *  Is this correct?  I want to create a right triangle on screen like this
                 *  |\
                 *  | \
                 *  |  \
                 *  |   \
                 *  |____\  though with a 90/45/45 degree spread rather than this poor representation.
                 */
        float v[] = {
            0.0f, 1.0f, 0.0f,
            0.0f, 0.0f, 0.0f,
            1.0f, 0.0f, 0.0f
        };
        s.setVertices(v);
        return s;
    }

    public static Shape makeShapeFromVertices(float pVerts[]){
        Shape s = new Shape();
        s.setVertices(pVerts);
        return s;
    }


    private float x = 0.0f;
    private float y = 0.0f;
    private float z = 0.0f;
    private float[] mVertices;
    private FloatBuffer mVertexBuffer;






    public void setVertices(float pVerts[]){
        mVertices = pVerts;
        ByteBuffer bb = ByteBuffer.allocateDirect(mVertices.length * 4);
        bb.order(ByteOrder.nativeOrder());
        mVertexBuffer = bb.asFloatBuffer();
        mVertexBuffer.put(mVertices);
        mVertexBuffer.position(0);
    }

    public float[] getVertices(){
        return mVertices;
    }

    private Shape(){

    }


    @Override
    public void draw(GL10 gl) {


        /*
         * I believe the problem is here... but I don't understand how or why?
         */
        gl.glTranslatef(x, y, z);
        gl.glFrontFace(GL10.GL_CW);
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVertexBuffer);
        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, mVertices.length);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glTranslatef(-x, -y, -z);

    }



}

编辑：我知道该教程与我的版本有些不同。我正在尝试从中推论并进行实验...我对差异完全感到惊讶和惊讶，并想知道它们为什么存在，以及如何避免我在渲染中发现的令人不快的结果方案。

最佳答案

你应该更换

glDrawArrays(GL10.GL_TRIANGLE_STRIP, ...)

与

glDrawArrays(GL10.GL_TRIANGLES, ...)

我认为当您绘制一个简单的三角形而不是四边形时，这就是问题的原因。

问候