The Preview Swatch resides in the right panel of the Asset Editor, rendering all changes done to the currently selected asset. This is a quick preview of materials, textures and lights. It has several controls that can be customized for your workflow.
You can enable or disable the live preview of the swatch by pressing the corresponding button (/). As the Preview Swatch is an actual render, it might require some additional computing power. The Stop live preview button comes in handy in such situations. When you stop the live preview, you have the option to Preview the asset once (). The swatch will render the current settings of the asset, but will not take into consideration any changes done to it later.
When using the live preview swatch, there are other ways to reduce resource usage – choose the resolution of the rendered swatch from 100% (1/1) (which is the best quality, but is a slower render), 50%(1/2), 25%(1/4) and 12.5% (1/8) (which trades off image quality for refresh speed).
Selecting the scene used to preview the asset () is available for materials and textures. You can choose from Generic, Fabric, Floor, Ground, Subsurface Scattering, Wall and Wall Closeup.
Pulling the bottom line of the Preview Swatch up and down reduces or expands the swatch.
For Material assets, you can also choose among several swatch scenes. Some are more suitable than others at displaying certain material types. For example, a Brick material will be best seen in a wall preview, instead of a shader ball.
The pin () on the top left is used to preview a specific asset regardless of the currently selected one. It will display the pinned asset until unpinned.
When changing the Units of a given light, its preview will be updated accordingly. Changes of the light intensity value are displayed up to a certain amount in order to guarantee the preview remains illustrative.
Using the Stop Preview Swatch option releases the V-Ray Render node License, if there is no other rendering process taking place.