use PBO for timelapse data read

src/app_events.cpp

@@ -89,18 +89,16 @@ void App::tick(float dt)
             canvas->m_canvas->m_dirty_stroke = false;
             LOG("rec tick");
 
-            Texture2D equirect;
+            PBO equirect;
             App::I->render_task([&] {
                 Canvas::I->draw_merge(true);
-                equirect = Canvas::I->m_layers_merge.gen_equirect(Canvas::I->m_encoder->frame_size() / 4);
+                equirect = Canvas::I->m_layers_merge.gen_equirect_pbo(Canvas::I->m_encoder->frame_size() / 4);
             });
-            auto img = std::make_unique<Image>(equirect.get_image());
             {
                 std::lock_guard<std::mutex> lock(rec_mutex);
-                rec_frames.emplace_back(std::move(img));
+                rec_frames.emplace_back(std::make_unique<PBO>(std::move(equirect)));
                 rec_cv.notify_all();
             }
-            equirect.destroy();
         }
     }
 }