To switch from standard Minecraft lighting to path-tracing lighting and realistic shadows, you need to select the pack inside your shader loader menu. Because shaders require a loader such as Iris or OptiFine, make sure you launch the game using that profile first.
Selecting the Shader Pack
1. Load into the main menu or pause an active world, then open Options and click Video Settings.
2. Open the Shaders (or Shader Packs) menu.
3. Confirm that TB BestGraphic Shaders appears in the list. If the list is empty, use the menu button to open your shader folder and make sure the pack is placed directly inside it without an extra wrapper folder.
4. Click TB BestGraphic Shaders and apply your changes. Give the game a moment to reload chunks and update lighting.
Checking Lighting and Vanilla Clarity
Once back in your world, look at sunlight angles around trees or buildings to verify realistic shadows are rendering properly. Place a light-emitting block such as a torch or lantern indoors to see the path-tracing lighting bounce across nearby walls. The pack preserves the classic vanilla look, so standard blocks remain immediately recognizable while gaining cleaner visual clarity and sharper shadow edges.