android - 如何在 OpenGL ES 2.0 中处理更多网格？

Question

我最近学习了适用于 Windows 的 OpenGL，现在我想在 Android 上尝试一下。我检查了一些教程，现在我已经开始破解这个示例：http: //blog.shayanjaved.com/2011/03/13/shaders-android/

在这个应用程序中，您可以在网格之间进行选择，但我想同时绘制其中两个。我做了一个drawRoad函数和一个drawCar函数。

private void drawCar(int program){



    /*** DRAWING OBJECT **/
    // Get buffers from mesh
    Object3D ob = this._objects[this.CUBE];
    Mesh mesh = ob.getMesh();
    FloatBuffer _vb = mesh.get_vb();
    ShortBuffer _ib = mesh.get_ib();

    short[] _indices = mesh.get_indices();

    // Vertex buffer

    // the vertex coordinates
    _vb.position(TRIANGLE_VERTICES_DATA_POS_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "aPosition"), 3, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "aPosition"));

    // the normal info
    _vb.position(TRIANGLE_VERTICES_DATA_NOR_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "aNormal"), 3, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "aNormal"));

    // Texture info

    // bind textures
    if (ob.hasTexture()) {// && enableTexture) {
        // number of textures
        int[] texIDs = ob.get_texID(); 

        for(int i = 0; i < _texIDs.length; i++) {
            GLES20.glActiveTexture(GLES20.GL_TEXTURE0 + i);
            Log.d("TEXTURE BIND: ", i + " " + texIDs[i]);
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texIDs[i]);
            GLES20.glUniform1i(GLES20.glGetUniformLocation(program, "texture" + (i+1)), i);
        }
    }

    // enable texturing? [fix - sending float is waste]
    GLES20.glUniform1f(GLES20.glGetUniformLocation(program, "hasTexture")/*shader.hasTextureHandle*/, ob.hasTexture() && enableTexture ? 2.0f : 0.0f);

    // texture coordinates
    _vb.position(TRIANGLE_VERTICES_DATA_TEX_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "textureCoord")/*shader.maTextureHandle*/, 2, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "textureCoord"));//GLES20.glEnableVertexAttribArray(shader.maTextureHandle);

    // Draw with indices
    GLES20.glDrawElements(GLES20.GL_TRIANGLES, _indices.length, GLES20.GL_UNSIGNED_SHORT, _ib);
    checkGlError("glDrawElements");

    /** END DRAWING OBJECT ***/

}



private void drawRoad(int program){


    /*** DRAWING OBJECT **/
    // Get buffers from mesh
    Object3D ob = this._objects[this.ROAD];
    Mesh mesh = ob.getMesh();
    FloatBuffer _vb = mesh.get_vb();
    ShortBuffer _ib = mesh.get_ib();

    short[] _indices = mesh.get_indices();

    // Vertex buffer

    // the vertex coordinates
    _vb.position(TRIANGLE_VERTICES_DATA_POS_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "aPosition"), 3, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "aPosition"));

    // the normal info
    _vb.position(TRIANGLE_VERTICES_DATA_NOR_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "aNormal"), 3, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "aNormal"));

    // Texture info

    // bind textures
    if (ob.hasTexture()) {// && enableTexture) {
        // number of textures
        int[] texIDs = ob.get_texID(); 

        for(int i = 0; i < _texIDs.length; i++) {
            GLES20.glActiveTexture(GLES20.GL_TEXTURE0 + i);
            //Log.d("TEXTURE BIND: ", i + " " + texIDs[i]);
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texIDs[i]);
            GLES20.glUniform1i(GLES20.glGetUniformLocation(program, "texture" + (i+1)), i);
        }
    }

    // enable texturing? [fix - sending float is waste]
    GLES20.glUniform1f(GLES20.glGetUniformLocation(program, "hasTexture")/*shader.hasTextureHandle*/, ob.hasTexture() && enableTexture ? 2.0f : 0.0f);

    // texture coordinates
    _vb.position(TRIANGLE_VERTICES_DATA_TEX_OFFSET);
    GLES20.glVertexAttribPointer(GLES20.glGetAttribLocation(program, "textureCoord")/*shader.maTextureHandle*/, 2, GLES20.GL_FLOAT, false,
            TRIANGLE_VERTICES_DATA_STRIDE_BYTES, _vb);
    GLES20.glEnableVertexAttribArray(GLES20.glGetAttribLocation(program, "textureCoord"));//GLES20.glEnableVertexAttribArray(shader.maTextureHandle);

    // Draw with indices
    GLES20.glDrawElements(GLES20.GL_TRIANGLES, _indices.length, GLES20.GL_UNSIGNED_SHORT, _ib);
    checkGlError("glDrawElements");

    /** END DRAWING OBJECT ***/

之后，我进行了一些基本的转换并将矩阵发送到 onDrawFrame 函数中的着色器：

public void onDrawFrame(GL10 glUnused) {
    // Ignore the passed-in GL10 interface, and use the GLES20
    // class's static methods instead.
    GLES20.glClearColor(.0f, .0f, .0f, 1.0f);
    GLES20.glClear( GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);

    GLES20.glUseProgram(0);
    // the current shader
    Shader shader = _shaders[this._currentShader]; // PROBLEM!
    int program = shader.get_program();

    // Start using the shader
    GLES20.glUseProgram(program);
    checkGlError("glUseProgram");

    // eye position
    GLES20.glUniform3fv(GLES20.glGetUniformLocation(program, "eyePos")/*shader.eyeHandle*/, 1, eyePos, 0);

    setLight(program);


    Matrix.setIdentityM(mMMatrix, 0);
    Matrix.setIdentityM(mTransMatrix, 0);

    Matrix.translateM(mTransMatrix, 0, 2.0f, 5.0f, 5.0f);

    Matrix.multiplyMM(mMMatrix, 0, mMMatrix, 0, mTransMatrix, 0);    //Translate
    Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);      //View
    Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0); //Proj

    // send to the shader
    GLES20.glUniformMatrix4fv(GLES20.glGetUniformLocation(program, "uMVPMatrix"), 1, false, mMVPMatrix, 0);

    // Create the normal modelview matrix
    // Invert + transpose of mvpmatrix
    Matrix.invertM(normalMatrix, 0, mMVPMatrix, 0);
    Matrix.transposeM(normalMatrix, 0, normalMatrix, 0);

    // send to the shader
    GLES20.glUniformMatrix4fv(GLES20.glGetUniformLocation(program, "normalMatrix"), 1, false, mMVPMatrix, 0);

    drawCar(program);


    //**********************************************************************************************************

    Matrix.setIdentityM(mMMatrix, 0);

    Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);      //View
    Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0); //Proj

    // send to the shader
    GLES20.glUniformMatrix4fv(GLES20.glGetUniformLocation(program, "uMVPMatrix"), 1, false, mMVPMatrix, 0);

    // Create the normal modelview matrix
    // Invert + transpose of mvpmatrix
    Matrix.invertM(normalMatrix, 0, mMVPMatrix, 0);
    Matrix.transposeM(normalMatrix, 0, normalMatrix, 0);

    // send to the shader
    GLES20.glUniformMatrix4fv(GLES20.glGetUniformLocation(program, "normalMatrix"), 1, false, mMVPMatrix, 0);


    drawRoad(program);



}

两个对象都会被绘制，但问题是，两个不同的对象存在于两个不同的世界中。如果我首先绘制道路，然后在调用 drawCar 函数之后，无论我是否在 Y 轴上将其平移 -100.0，汽车（实际上它是一个立方体）都将始终可见。

对象从网格文件中读取并正确解析为顶点缓冲区和索引缓冲区，并且它们自己完美地显示出来。

如何将两个（或更多）对象放在同一个空间中？