我一直致力于让OpenGL在场景中渲染多个不同的实体。

根据http://www.opengl.org/wiki/Vertex_Specification，

顶点数组对象应该记住顶点缓冲区对象绑定到GL_ARRAY_BUFFER，GL_ELEMENT_ARRAY_BUFFER。（或者至少我是这样理解它的意思的）

然而，即使我在绑定任何 vao 后调用 draw，应用程序也将只使用绑定到GL_ARRAY_BUFFER的最后一个。

问题-我理解得对吗？考虑到下面的代码，调用gl函数的所有顺序是否正确？

void OglLayer::InitBuffer()
{
    std::vector<float> out;
    std::vector<unsigned> ibOut;

    glGenVertexArrays(V_COUNT, vaos);
    glGenBuffers(B_COUNT, buffers);

    // -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= //
    glBindVertexArray(vaos[V_PLANE]);

    PlaneBuffer(out, ibOut, 0.5f, 0.5f, divCount, divCount);

    OGL_CALL(glBindBuffer(GL_ARRAY_BUFFER, buffers[B_PLANE_VERTEX]));
    OGL_CALL(glBufferData(GL_ARRAY_BUFFER, out.size()*sizeof(float), out.data(), GL_DYNAMIC_DRAW));
    //GLuint vPosition = glGetAttribLocation( programs[P_PLANE], "vPosition" );
    OGL_CALL(glEnableVertexAttribArray(0));
    //OGL_CALL(glVertexAttribPointer( vPosition, 3, GL_FLOAT, GL_FALSE, sizeof(float)*3, BUFFER_OFFSET(0) ));
    OGL_CALL(glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, sizeof(float)*3, BUFFER_OFFSET(0) ));
    bufferData[B_PLANE_VERTEX].cbSize = sizeof(float) * out.size();
    bufferData[B_PLANE_VERTEX].elementCount = out.size()/3;
    OGL_CALL(glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[B_PLANE_INDEX]));
    OGL_CALL(glBufferData(GL_ELEMENT_ARRAY_BUFFER, ibOut.size()*sizeof(unsigned), ibOut.data(), GL_STATIC_DRAW));
    bufferData[B_PLANE_INDEX].cbSize = sizeof(float) * ibOut.size();
    bufferData[B_PLANE_INDEX].elementCount = ibOut.size();

    // -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= //
    glBindVertexArray(vaos[V_CUBE]);

    out.clear();
    ibOut.clear();

    GenCubeMesh(out, ibOut);

    glBindBuffer(GL_ARRAY_BUFFER, buffers[B_CUBE_VERTEX]);
    glBufferData(GL_ARRAY_BUFFER, out.size()*sizeof(float), out.data(), GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float), BUFFER_OFFSET(0));
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[B_CUBE_INDEX]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned), ibOut.data(), GL_STATIC_DRAW);
}


void RenderPlane::Render( float dt )
{            
    // Putting any vao here always results in using the lastly buffer bound.
    OGL_CALL(glBindVertexArray(g_ogl.vaos[m_pRender->vao]));

    {
        OGL_CALL(glUseProgram(g_ogl.programs[m_pRender->program]));

        // uniform location
        GLint loc = 0;

        // Send Transform Matrix ( Rotate Cube over time )
        loc = glGetUniformLocation(g_ogl.programs[m_pRender->program], "transfMat");
        auto transf = m_pRender->pParent->m_transform->CreateTransformMatrix();
        glUniformMatrix4fv(loc, 1, GL_TRUE, &transf.matrix()(0,0));

        // Send View Matrix
        loc = glGetUniformLocation(g_ogl.programs[m_pRender->program], "viewMat");
        mat4 view = g_ogl.camera.transf().inverse();
        glUniformMatrix4fv(loc, 1, GL_TRUE, &view(0,0));

        // Send Projection Matrix
        loc = glGetUniformLocation(g_ogl.programs[m_pRender->program], "projMat");
        mat4 proj = g_ogl.camera.proj();
        glUniformMatrix4fv(loc, 1, GL_TRUE, &proj(0,0));
    }

    OGL_CALL(glDrawElements(GL_TRIANGLES, g_ogl.bufferData[m_pRender->ib].elementCount, GL_UNSIGNED_INT, 0));
}