使用OpenGL显示两个对象.纹理不像预期的那样行为

嗨，我试图使用opengl。）在前景中，2）矩形板只有一个纹理（深灰色木材）作为背景。当我评论矩形板的显示的代码部分时，旋转立方体显示两个纹理（木制板条箱和笑脸）。否则，多维数据集仅显示木制板条箱质地，深灰色木材质地也显示在矩形板上，即笑脸从旋转立方体。请查找图像1）http://oi68.tinypic.com/2la4r3c.jpg（带有矩形板的代码的部分）和2）http://i67.tinypic.com/9U9RPF.jpg（未注释代码的矩形板）。代码的恢复部分在下面粘贴

// Rotating Cube ===================================================
// Texture of wooden crate
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture1);
glUniform1i(glGetUniformLocation(ourShader_box.Program, "ourTexture1"), 0);
// Texture of a smiley
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture2);
glUniform1i(glGetUniformLocation(ourShader_box.Program, "ourTexture2"), 1);
// lets use the box shader for the cube
ourShader_box.Use();
// transformations for the rotating cube ---------------------------------
glm::mat4 model_box, model1, model2;
glm::mat4 view_box;
glm::mat4 perspective;
perspective = glm::perspective(45.0f, (GLfloat)width_screen/(GLfloat)height_screen, 0.1f, 200.0f);
model1 = glm::rotate(model_box, (GLfloat)glfwGetTime()*1.0f, glm::vec3(0.5f, 1.0f, 0.0f));
model2 = glm::rotate(model_box, (GLfloat)glfwGetTime()*1.0f, glm::vec3(0.0f, 1.0f, 0.5f));
model_box = model1 * model2;
view_box= glm::translate(view_box, glm::vec3(1.0f, 0.0f, -3.0f));
GLint modelLoc_box = glGetUniformLocation(ourShader_box.Program, "model");
GLint viewLoc_box = glGetUniformLocation(ourShader_box.Program, "view");
GLint projLoc_box = glGetUniformLocation(ourShader_box.Program, "perspective");
glUniformMatrix4fv(modelLoc_box, 1, GL_FALSE, glm::value_ptr(model_box));
glUniformMatrix4fv(viewLoc_box, 1, GL_FALSE, glm::value_ptr(view_box));
glUniformMatrix4fv(projLoc_box, 1, GL_FALSE, glm::value_ptr(perspective));  
// --------------------------------------------------------------------
// Draw calls
glBindVertexArray(VAO_box);
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);
// Rectangular Plate =====================================================
// Background Shader
ourShader_bg.Use();
// Texture of dark grey wood
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, texture_wood);
glUniform1i(glGetUniformLocation(ourShader_bg.Program, "ourTexture3"), 2);
// Transformations -------------------------------------------
glm::mat4 model_bg;
glm::mat4 view_bg;
GLint modelLoc_bg = glGetUniformLocation(ourShader_bg.Program, "model");
GLint viewLoc_bg= glGetUniformLocation(ourShader_bg.Program, "view");
GLint projLoc_bg = glGetUniformLocation(ourShader_bg.Program, "perspective");
glUniformMatrix4fv(modelLoc_bg, 1, GL_FALSE, glm::value_ptr(model_bg));
glUniformMatrix4fv(viewLoc_bg, 1, GL_FALSE, glm::value_ptr(view_bg));
glUniformMatrix4fv(projLoc_bg, 1, GL_FALSE, glm::value_ptr(perspective));   
// -----------------------------------------------------------
// Draw calls
glBindVertexArray(VAO_bg);
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindVertexArray(0);
// =================================================================

我有两个有关此代码的问题。

• 为什么笑脸消失了？
• 这是否应该如何渲染多个对象？我知道OpenGL不在乎对象，它只关心顶点，但是在这种情况下，这些是独立的，不相交的对象。因此，我是否应该将它们作为两个VBO绑定到一个VAO的两个VBO或单独的VBO绑定到每个对象的两个VAO？还是这样，无论哪种方式都很好 - 取决于编码器的选择和代码的优雅？