为什么我的代码在 opengl 中没有显示在顶点数组 object 的手机模拟器上

Question

我是新手，但我想做的是使用顶点数组 object 在手机模拟器上显示一些东西。 但问题是它没有在手机上显示任何内容。 我对使用顶点数组对象的理解是，VAO 类似于一个文件夹，可以指向不同的缓冲区，并且在 VAO 内部有顶点缓冲区对象。 我在代码中所做的是创建两个缓冲区和一个 VAO。 将缓冲区绑定到名为 mVBOIds 的数组。 然后将 VAO 绑定到它自己的数组，然后我使用缓冲区设置顶点。

为了填充这些缓冲区，我有一个名为 torus2.raw 的文件，其中包含如下所示的数据：

# Data order:
# Vertex
# Normal vector
# Texture coordinate
12.329425 0.0 -8.957851 1.0
-0.809017 1.0E-6 0.587785 0.0
0.05 1.0

我们有数据的顺序，顶点有 4 个数据，法向量有 4 个，然后纹理坐标有 2 个数据。

这是创建缓冲区和 VAO 的那部分代码及其在 onSurfaceCreated 方法中的代码：

        // Generate VBO Ids and load the VBOs with data
        GLES30.glGenBuffers ( 2, mVBOIds, 0 );

        GLES30.glBindBuffer ( GLES30.GL_ARRAY_BUFFER, mVBOIds[0] );
        mVertices.position ( 0 );
        GLES30.glBufferData ( GLES30.GL_ARRAY_BUFFER, mVertices.remaining() * 4,
                mVertices, GLES30.GL_STATIC_DRAW );

        GLES30.glBindBuffer ( GLES30.GL_ELEMENT_ARRAY_BUFFER, mVBOIds[1] );
        mNormals.position ( 0 );
        GLES30.glBufferData ( GLES30.GL_ELEMENT_ARRAY_BUFFER, 4 * mNormals.remaining(),
                mNormals, GLES30.GL_STATIC_DRAW );

        // Generate VAO Id
        GLES30.glGenVertexArrays ( 1, mVAOId, 0 );

        // Bind the VAO and then setup the vertex
        // attributes
        GLES30.glBindVertexArray ( mVAOId[0] );

        GLES30.glBindBuffer ( GLES30.GL_ARRAY_BUFFER, mVBOIds[0] );
        GLES30.glBindBuffer ( GLES30.GL_ELEMENT_ARRAY_BUFFER, mVBOIds[1] );

        GLES30.glEnableVertexAttribArray (VERTEX_POS_INDX);
        GLES30.glEnableVertexAttribArray (VERTEX_NORM_INDX);

        GLES30.glVertexAttribPointer ( VERTEX_POS_INDX, VERTEX_POS_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                0 );

        GLES30.glVertexAttribPointer (VERTEX_NORM_INDX, VERTEX_NORM_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                ( VERTEX_POS_SIZE * 4 ) );

        // Reset to the default VAO
        GLES30.glBindVertexArray ( 0 );

        GLES30.glClearColor ( 0.15f, 0.15f, 0.15f, 1.0f );
        GLES30.glEnable(GLES30.GL_DEPTH_TEST);

在此之后，当我设置了缓冲区和 VAO 时，我使用 onDrawFrame 方法让它显示在显示器中：

    public void onDrawFrame ( GL10 glUnused )
    {
        // Initiate the model-view matrix as identity matrix
        Matrix.setIdentityM(mViewMatrix, 0);

        // Define a translation transformation
        Matrix.translateM(mViewMatrix, 0, 0.0f, 0.0f, -60.0f);
        // Define a rotation transformation
        Matrix.rotateM(mViewMatrix, 0, 90.0f, 1.0f, 0.0f, 0.0f);

        // Calculate the model-view and projection transformation as composite transformation
        Matrix.multiplyMM (mMVPMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);

        // Clear the color buffer
        GLES30.glClear ( GLES30.GL_COLOR_BUFFER_BIT | GLES30.GL_DEPTH_BUFFER_BIT );

        // Use the program object
        GLES30.glUseProgram ( mProgramObject );

        // Make MVP matrix accessible in the vertex shader
        mMVPMatrixHandle = GLES30.glGetUniformLocation(mProgramObject, "uMVPMatrix");
        GLES30.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

        // Light position:
        vLightPositionHandle = GLES30.glGetUniformLocation(mProgramObject, "vLightPosition");
        GLES30.glUniform4fv(vLightPositionHandle, 1, lightPosition, 0);

        // Light color:
        vLightColorDfHandle = GLES30.glGetUniformLocation(mProgramObject, "vLightColorDf");
        GLES30.glUniform4fv(vLightColorDfHandle, 1, lightColorDf, 0);

        // Material color:
        vMaterialColorDfHandle = GLES30.glGetUniformLocation(mProgramObject, "vMaterialColorDf");
        GLES30.glUniform4fv(vMaterialColorDfHandle, 1, materialColorDf, 0);

        GLES30.glBindVertexArray ( mVAOId[0] );

        // Draw with the VAO settings
        GLES30.glDrawElements ( GLES30.GL_TRIANGLES, mNormals.remaining(), GLES30.GL_UNSIGNED_SHORT, 0 );

        // Return to the default VAO
        GLES30.glBindVertexArray ( 0 );
    }

但问题是我无法显示任何内容。 我试图仔细检查变量，检查变量是否为空等，但我找不到罪魁祸首。 也可能是我对代码的理解不同并犯了逻辑错误，但我看不到它是什么。 结果应该是一个蓝色的甜甜圈形状 model。

这是整个代码：

    import android.content.Context;
    import android.opengl.GLES30;
    import android.opengl.GLSurfaceView;
    import android.opengl.Matrix;
    import android.util.Log;

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

    import javax.microedition.khronos.egl.EGLConfig;
    import javax.microedition.khronos.opengles.GL10;

    import se.hig.dvg306.modul3app.tools.ResourceHandler;

    public class Modul3Renderer implements GLSurfaceView.Renderer
    {
    //
    // Constructor - loads model data from a res file and creates byte buffers for
    // vertex data and for normal data
    //
    public Modul3Renderer (Context context)
    {
        appContext = context;

        Log.e(TAG, "--->>>      Creating ModelLoader...");
        ModelLoader modelLoader = new ModelLoaderImpl ();
        Log.e(TAG, "--->>>      ...finished.");

        Log.e(TAG, "--->>>      Loading model...");
        Log.e(TAG, "--->>>      Starting with vertices...");
        float[] mVerticesData; //= new float[0];

        try {
            mVerticesData = modelLoader.loadModel (context, R.raw.torus2, 0, 10, 0);
        } catch (IOException e) {
            throw new RuntimeException (e);
        }
        Log.e(TAG, "--->>>      ...finished.");

        // Process vertex data
        // 4: because of 4 elements per vertex position
        nbrOfVertices = mVerticesData.length / 10;

        mVertices = ByteBuffer.allocateDirect(mVerticesData.length * 4)
                .order(ByteOrder.nativeOrder()).asFloatBuffer();
        mVertices.put(mVerticesData).position(0);

        Log.e(TAG, "--->>>      Starting with normals...");
        float[] mNormalData; //= new float[0];

        try {
            mNormalData = modelLoader.loadModel (context, R.raw.torus2, 4, 4, 6);
        } catch (IOException e) {
            throw new RuntimeException (e);
        }
        Log.e(TAG, "--->>>      ...finished.");

        // Process normal data
        // 4: because of 4 elements per vertex position
        nbrOfNormals = mNormalData.length / 4;

        mNormals = ByteBuffer.allocateDirect(mNormalData.length * 4)
                .order(ByteOrder.nativeOrder()).asFloatBuffer();
        mNormals.put(mNormalData).position(0);
    }

    ///
    // Create a shader object, load the shader source, and
    // compile the shader.
    //
    private int createShader(int type, String shaderSrc )
    {
        int shader;
        int[] compiled = new int[1];

        // Create the shader object
        shader = GLES30.glCreateShader ( type );

        if ( shader == 0 )
        {
            return 0;
        }

        // Load the shader source
        GLES30.glShaderSource ( shader, shaderSrc );

        // Compile the shader
        GLES30.glCompileShader ( shader );

        // Check the compile status
        GLES30.glGetShaderiv ( shader, GLES30.GL_COMPILE_STATUS, compiled, 0 );

        if ( compiled[0] == 0 )
        {
            Log.e ( TAG, GLES30.glGetShaderInfoLog ( shader ) );
            GLES30.glDeleteShader ( shader );
            return 0;
        }

        return shader;
    }

    ///
    // Initialize the shader and program object
    //
    public void onSurfaceCreated ( GL10 glUnused, EGLConfig config )
    {
        int vertexShader;
        int fragmentShader;
        int programObject;
        int[] linked = new int[1];


        // Load the source code for the vertex shader program from a res file:
        try {
            vShaderStr = ResourceHandler.readTextData(appContext, R.raw.vertex_shader);
        } catch (IOException e) {
            Log.e ( TAG, "--->>>      Could not load source code for vertex shader.");
            throw new RuntimeException (e);
        }
        Log.e ( TAG, "--->>>      Loaded vertex shader: " + vShaderStr);

        // Load the source code for the fragment shader program from a res file:
        try {
            fShaderStr = ResourceHandler.readTextData(appContext, R.raw.fragment_shader);
        } catch (IOException e) {
            Log.e ( TAG, "--->>>      Could not load source code for fragment shader.");
            throw new RuntimeException (e);
        }
        Log.e ( TAG, "--->>>      Loaded fragment shader: " + fShaderStr);

        // Create the vertex/fragment shaders
        vertexShader = createShader( GLES30.GL_VERTEX_SHADER, vShaderStr );
        fragmentShader = createShader( GLES30.GL_FRAGMENT_SHADER, fShaderStr );

        // Create the program object
        programObject = GLES30.glCreateProgram();

        if ( programObject == 0 )
        {
            return;
        }

        GLES30.glAttachShader ( programObject, vertexShader );
        GLES30.glAttachShader ( programObject, fragmentShader );

        // Bind vPosition to attribute 0
        GLES30.glBindAttribLocation ( programObject, 0, "vPosition" );

        // Bind vNormal to attribute 1
        GLES30.glBindAttribLocation ( programObject, 1, "vNormal" );

        // Link the program
        GLES30.glLinkProgram ( programObject );

        // Check the link status
        GLES30.glGetProgramiv ( programObject, GLES30.GL_LINK_STATUS, linked, 0 );

        if ( linked[0] == 0 )
        {
            Log.e ( TAG, "Error linking program:" );
            Log.e ( TAG, GLES30.glGetProgramInfoLog ( programObject ) );
            GLES30.glDeleteProgram ( programObject );
            return;
        }

        // Store the program object
        mProgramObject = programObject;

        // Generate VBO Ids and load the VBOs with data
        GLES30.glGenBuffers ( 2, mVBOIds, 0 );

        GLES30.glBindBuffer ( GLES30.GL_ARRAY_BUFFER, mVBOIds[0] );
        mVertices.position ( 0 );
        GLES30.glBufferData ( GLES30.GL_ARRAY_BUFFER, mVertices.remaining() * 4,
                mVertices, GLES30.GL_STATIC_DRAW );

        GLES30.glBindBuffer ( GLES30.GL_ELEMENT_ARRAY_BUFFER, mVBOIds[1] );
        mNormals.position ( 0 );
        GLES30.glBufferData ( GLES30.GL_ELEMENT_ARRAY_BUFFER, 4 * mNormals.remaining(),
                mNormals, GLES30.GL_STATIC_DRAW );

        // Generate VAO Id
        GLES30.glGenVertexArrays ( 1, mVAOId, 0 );

        // Bind the VAO and then setup the vertex
        // attributes
        GLES30.glBindVertexArray ( mVAOId[0] );

        GLES30.glBindBuffer ( GLES30.GL_ARRAY_BUFFER, mVBOIds[0] );
        GLES30.glBindBuffer ( GLES30.GL_ELEMENT_ARRAY_BUFFER, mVBOIds[1] );

        GLES30.glEnableVertexAttribArray (VERTEX_POS_INDX);
        GLES30.glEnableVertexAttribArray (VERTEX_NORM_INDX);

        GLES30.glVertexAttribPointer ( VERTEX_POS_INDX, VERTEX_POS_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                0 );

        GLES30.glVertexAttribPointer (VERTEX_NORM_INDX, VERTEX_NORM_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                ( VERTEX_POS_SIZE * 4 ) );

        // Reset to the default VAO
        GLES30.glBindVertexArray ( 0 );

        GLES30.glClearColor ( 0.15f, 0.15f, 0.15f, 1.0f );
        GLES30.glEnable(GLES30.GL_DEPTH_TEST);
    }

    //
    // Draw a torus using the shader pair created in onSurfaceCreated()
    //
    public void onDrawFrame ( GL10 glUnused )
    {
        // Initiate the model-view matrix as identity matrix
        Matrix.setIdentityM(mViewMatrix, 0);

        // Define a translation transformation
        Matrix.translateM(mViewMatrix, 0, 0.0f, 0.0f, -60.0f);
        // Define a rotation transformation
        Matrix.rotateM(mViewMatrix, 0, 90.0f, 1.0f, 0.0f, 0.0f);

        // Calculate the model-view and projection transformation as composite transformation
        Matrix.multiplyMM (mMVPMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);

        // Clear the color buffer
        GLES30.glClear ( GLES30.GL_COLOR_BUFFER_BIT | GLES30.GL_DEPTH_BUFFER_BIT );

        // Use the program object
        GLES30.glUseProgram ( mProgramObject );

        // Make MVP matrix accessible in the vertex shader
        mMVPMatrixHandle = GLES30.glGetUniformLocation(mProgramObject, "uMVPMatrix");
        GLES30.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

        // Light position:
        vLightPositionHandle = GLES30.glGetUniformLocation(mProgramObject, "vLightPosition");
        GLES30.glUniform4fv(vLightPositionHandle, 1, lightPosition, 0);

        // Light color:
        vLightColorDfHandle = GLES30.glGetUniformLocation(mProgramObject, "vLightColorDf");
        GLES30.glUniform4fv(vLightColorDfHandle, 1, lightColorDf, 0);

        // Material color:
        vMaterialColorDfHandle = GLES30.glGetUniformLocation(mProgramObject, "vMaterialColorDf");
        GLES30.glUniform4fv(vMaterialColorDfHandle, 1, materialColorDf, 0);

        GLES30.glBindVertexArray ( mVAOId[0] );

        // Draw with the VAO settings
        GLES30.glDrawElements ( GLES30.GL_TRIANGLES, mNormals.remaining(), GLES30.GL_UNSIGNED_SHORT, 0 );

        // Return to the default VAO
        GLES30.glBindVertexArray ( 0 );
    }

    //
    // Handle surface changes
    //
    public void onSurfaceChanged ( GL10 glUnused, int width, int height )
    {
        mWidth = width;
        mHeight = height;

        GLES30.glViewport(0, 0, width, height);

        float ratio = (float) width / height;

        // this projection matrix is applied to object coordinates
        Matrix.frustumM(mProjectionMatrix, 0, -ratio, ratio, -1.0f, 1.0f, 0.5f, 1000.0f);
    }

    // Member variables

    private Context appContext;

    private int mWidth;
    private int mHeight;

    private int nbrOfVertices;
    private FloatBuffer mVertices;

    final int VERTEX_POS_SIZE   = 4; // x, y and z
    final int VERTEX_NORM_SIZE = 4; // r, g, b, and a

    final int VERTEX_POS_INDX   = 0;
    final int VERTEX_NORM_INDX = 1;

    private int [] mVBOIds = new int[2];
    private int [] mVAOId = new int[1];

    private int nbrOfNormals;
    private FloatBuffer mNormals;

    private int mProgramObject;
    private int mMVPMatrixHandle;

    // Transformation data:
    private final float[] mMVPMatrix = new float[16];
    private final float[] mProjectionMatrix = new float[16];
    private final float[] mViewMatrix = new float[16];

    final int VERTEX_STRIDE = ( 4 * ( VERTEX_POS_SIZE +  VERTEX_NORM_SIZE ) );

    // Light position and color (only diffuse term now):
    private int vLightPositionHandle;
    private final float lightPosition [] = {175.0f, 75.0f, 125.0f, 0.0f};
    // Light color (only diffuse term now):
    private int vLightColorDfHandle;
    private final float lightColorDf [] = {0.98f, 0.98f, 0.98f, 1.0f};
    // Material color (only diffuse term now):
    private int vMaterialColorDfHandle;
    private final float materialColorDf [] = {0.62f, 0.773f, 0.843f, 1.0f};

    // To be read when creating the instance:
    private String vShaderStr;
    private String fShaderStr;

    private static String TAG = "Modul3Renderer";
    }

Answer 1

GL_ELEMENT_ARRAY_BUFFER object 用于索引，应包含完整数据。 您应该为法向量使用GL_ARRAY_BUFFER ：

GLES30.glBindBuffer ( GLES30.GL_ARRAY_BUFFER, mVBOIds[1] );
        mNormals.position ( 0 );
GLES30.glBufferData ( GLES30.GL_ARRAY_BUFFER, 4 * mNormals.remaining(),
        mNormals, GLES30.GL_STATIC_DRAW );

当调用glVertexAttribPointer时，当前绑定到目标ARRAY_BUFFER的缓冲区与指定的属性索引相关联，并且 object 的 ID 存储在当前绑定的 VAO 的 state 向量中。 所以你必须在调用glVertexAttribPointer之前绑定缓冲区 object ：

GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, mVBOIds[0]);
GLES30.glVertexAttribPointer ( VERTEX_POS_INDX, VERTEX_POS_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                0 );

GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, mVBOIds[1]);
GLES30.glVertexAttribPointer (VERTEX_NORM_INDX, VERTEX_NORM_SIZE,
                GLES30.GL_FLOAT, false, VERTEX_STRIDE,
                ( VERTEX_POS_SIZE * 4 ) );