鏡子
「鏡子」（Mirrors），是可反射場景的面板，其允許 VRChat 用戶查看自己角色的鏡像畫面。鏡子經過設定後也能同時看見其他用戶或所在世界的環境樣貌。很多世界都設有供用戶在前方進行社交活動所用的鏡子。
鏡子類型
個人鏡子
個人鏡子（Personal Mirror）是一種可由用戶自行召喚並手持移動的鏡子，並且僅有召喚鏡子的用戶自己能看見。
這項功能可以從動作選單（Action Menu）或主選單（Main Menu）中的設定（Settings）標籤頁啟用與設定。
Face Mirror
A face mirror is a type of mirror that displays the face of a user's avatar in their HUD. Face mirrors are designed to help a user stay aware of their avatar's facial expressions, especially if they're controlled by gestures. Unlike a traditional mirror, the face mirror does not portray depth. In desktop mode, the Face Mirror resolution scales with its displayed size up to 2048×2048 pixels. When streaming via Spout, it always renders at maximum resolution.
It can be enabled and configured via the Action Menu or the Main Menu's Settings page.
Calibration Mirror
A calibration mirror is a type of mirror that activates automatically when the user presses the "Calibrate FBT" button. It is visible only to the user who is calibrating and disappears once they are done. The calibration mirror displays only the user's avatar, controllers, and FBT tracker model, which can be set in the Main Menu's Settings. If "Display Calibration Visuals" is enabled under Tracking and IK, the calibration mirror will also reflect these, showing which tracking points the trackers will track when calibration is done.
It can be enabled via the Action Menu or the Main Menu's Settings page, but there are no configuration options for the calibration mirror.
Common setups
The mirror prefab allows for selection of which layers are to be shown in the reflection. Therefore, it is common that worlds have set up multiple different mirrors to toggle between. Which is why it usually breaks down to 3 options: high quality, low quality and transparent mirror. Some worlds offer even more specialized setups beyond these.
High quality
A high quality mirror acts as a mirror would in real life, reflecting the world and avatars around it from the perspective of the mirror.
Low quality
A low quality mirror usually mirrors the avatars around it at a lower resolution and replaces the reflection of the world with the skybox.
Transparent
A transparent mirror usually reflects the avatars around it while acting like a window, showing what appears behind the mirror, and also having a faint reflection of world from the mirror's perspective. It requires a special set up, which is also available through transparent mirror prefabs from the community.
Performance issues
Every object reflected in a mirror has to be rendered again, separately from what the user sees in the playable world. A mirror reflecting the whole world will double the performance cost of rendering the world. Occlusion culling does not work in mirror reflections, so a mirror facing a wall will still try to render everything behind the wall too.
Creators can reduce the performance cost for mirrors in many ways, such as:
- Disabling all mirrors by default. Only enable a mirror when the user pushes a button, or physically approaches them.
- Disabling mirrors when a user leaves the area. This will remove the rendering cost of a mirror when a player isn't using it. Users will often not do this themselves, so use a script to do it for them.
- Considering the placement of mirrors. A mirror facing away from the center of the world will have to render less than one facing inward.
- Changing the Layers a mirror reflects. A mirror only renders objects on the defined layers. For example, if you have a large outdoor world with a house in the middle, you could set the outdoor environment objects to the environment layer, and then disable the environment layer on the mirrors inside the house. This will stop the mirrors from trying to render the environment that they can't see.
When interacting with a Mirror in a world, users will be able to enable or toggle different options to save on performance, such as:
- Using only one mirror at a time.
- Choosing a lower quality option for a mirror, if available.
- Alternatively, substituting a world's mirror for your Personal Mirror.
- Adjust your mirror resolution under Graphics Settings.
SDK
World prefab
The VRChat SDK contains a prefab for a ready-to-use mirror that can be dragged into a scene. This prefab is found at the following path:
Packages\com.vrchat.worlds\Samples\UdonExampleScene\Prefabs\VRCMirror.prefab
Technical details
Mirrors render during Camera.onPreCull. World creators using scripts that depend on mirror render timing should account for this.
