text: void SpriteRenderer::initRenderData()
  {
      // configure VAO/VBO
      unsigned int VBO;
      float vertices[] = { 
          // pos      // tex
          0.0f, 1.0f, 0.0f, 1.0f,
          1.0f, 0.0f, 1.0f, 0.0f,
          0.0f, 0.0f, 0.0f, 0.0f, 
      
          0.0f, 1.0f, 0.0f, 1.0f,
          1.0f, 1.0f, 1.0f, 1.0f,
          1.0f, 0.0f, 1.0f, 0.0f
      };
  
      glGenVertexArrays(1, &this->quadVAO);
      glGenBuffers(1, &VBO);
      
      glBindBuffer(GL_ARRAY_BUFFER, VBO);
      glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
  
      glBindVertexArray(this->quadVAO);
      glEnableVertexAttribArray(0);
      glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
      glBindBuffer(GL_ARRAY_BUFFER, 0);  
      glBindVertexArray(0);
  }
  