OpenGL ES 2.0在屏幕上绘制纹理不起作用

// 示例代码：加载纹理
GLuint loadTexture(const char* imagePath) {
    GLuint textureID;
    glGenTextures(1, &textureID);
    glBindTexture(GL_TEXTURE_2D, textureID);
    
    // 设置纹理参数
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    
    // 加载图像数据
    int width, height, nrChannels;
    unsigned char *data = stbi_load(imagePath, &width, &height, &nrChannels, 0);
    if (data) {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    } else {
        std::cerr << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);
    
    return textureID;
}

// 示例代码：编译和链接着色器
GLuint compileShaders(const char* vertexShaderSource, const char* fragmentShaderSource) {
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    
    GLuint shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    
    // 检查编译和链接错误
    GLint success;
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success) {
        char infoLog[512];
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cerr << "Shader program linking failed: " << infoLog << std::endl;
    }
    
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    
    return shaderProgram;
}

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textureID);
glUniform1i(glGetUniformLocation(shaderProgram, "textureSampler"), 0);

glDisable(GL_DEPTH_TEST);