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When the mesh's → extension feature is active you will see a grid (number of tiles in U and V direction), a square with a solid line (“@ Fall “Fall Off from”), and a square with a dashed line (“@ Fall “Fall Off to”).
Render as points
With this mode, only the mesh's vertices will be displayed. Their size can be controlled with the associated “@ Points “Points size” parameter.
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Point size
When “Render as points” is active only the mesh's vertices will be displayed and here you can control their size.