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我对 OpenGL ES 2.0 有疑问。我设计了一个非常简单的框架来帮助我加载 OBJ 文件并在我的 Android 手机上绘制它们，但是我有 2 个我无法修复的错误：

  1. 在我更改方向并且 Activity 被抓取并重新加载之前，我的应用程序不会显示任何内容。在它重新加载之前，只能看到 GLES20.glClear() （我已将其设置为灰色）。

  2. 有时，当我加载 OBJ 并执行定位技巧时，我的一半脸不见了，我看到了间隙，但问题可能出在我使用的 OBJ 文件上。


package com.ideas.opengl;

import java.io.IOException;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLES20;
import android.opengl.GLSurfaceView.Renderer;
import android.opengl.Matrix;

public class DemoRenderer implements Renderer {
    public static int mProgramHandle;
    private int mMVPMatrixHandle;
    private float[] mModelMatrix = new float[16];
    private float[] mViewMatrix = new float[16];
    private float[] mProjectionMatrix = new float[16];
    private float[] mMVPMatrix = new float[16];

    public Object banana;

    private OpenGLDemoActivity activity;

    private int angle;

    public DemoRenderer(OpenGLDemoActivity activity) throws IOException {
        this.activity = activity;
    }



    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config){
        GLES20.glClearColor(0.65f, 0.65f, 0.65f, 0.65f);

        //GLES20.glEnable(GLES20.GL_CULL_FACE);

        GLES20.glEnable(GLES20.GL_DEPTH_TEST);

        GLES20.glEnable(GLES20.GL_TEXTURE_2D);

        Shader shader = null;
        try {
            shader = new Shader(activity, "simple");
        } catch (IOException e) {
            e.printStackTrace();
        }
        Vector position = new Vector();
        Vector speed = new Vector();
        Vector accel = new Vector();
        Model model = null;
        try {
            model = new Model("banana", activity);
        } catch (IOException e) {
            e.printStackTrace();
        }

        banana = new Object(position, speed, accel, model);

        mProgramHandle = shader.getProgramHandle();

        final float eyeX = 0.0f;
        final float eyeY = 0.0f;
        final float eyeZ = 3.5f;

        final float lookX = 0.0f;
        final float lookY = 0.0f;
        final float lookZ = -5.0f;

        final float upX = 0.0f;
        final float upY = 1.0f;
        final float upZ = 0.0f;

        Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ);

        mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_MVPMatrix");
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        GLES20.glViewport(0, 0, width, height);

        final float ratio = (float) width / height;
        final float left = -ratio;
        final float right = ratio;
        final float bottom = -1.0f;
        final float top = 1.0f;
        final float near = 1.0f;
        final float far = 10.0f;

        Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far);

    }


    @Override
    public void onDrawFrame(GL10 gl) {      
        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);

        angle++;

        Matrix.setIdentityM(mModelMatrix, 0);
        Matrix.rotateM(mModelMatrix, 0, angle, 0.0f, 1.0f, 1.0f);

        Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);

        Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);

        GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

        banana.draw();
    }
}

`

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2 回答 2

1

尝试了一些 glGetError() 并遇到了错误，一个是关于其值未更改的变量，另一个是如果该属性未在顶点着色器中使用，则 glGetAttributeLocation() 返回 -1。谢谢你的帮助！

于 2012-06-15T18:28:05.853 回答
1

几何问题可能是由于在矩阵乘法中对输入和输出使用相同的浮点数组： Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); 根据 multiplyMM() 规范，输入和输出数组可能没有重叠元素，但您使用相同的数组 mMVPMatrix 开头相同的索引 0。解决此问题的一种方法是使用另一个矩阵作为最后一次乘法结果的缓冲区，因此而不是：

Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

采用：

Matrix.multiplyMM(mMatrixFinal, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMatrixFinal, 0);
于 2016-05-14T17:13:38.357 回答