# WorldClass.server_onVoxelConstruction

Called when a cluster of voxels are added by a player

**Kind:** Callback

**Environments:** Game

## Game

**Callback side:** Server

``` { .lua .api-signature }
WorldClass:server_onVoxelConstruction( densityGain, positions )
```

[Open the full Game reference](../Game-Script-Environment/Classes/WorldClass.md#server_onvoxelconstruction)

**Parameters:**

| Name | Type | Description |
| --- | --- | --- |
| `self` | table | The class instance. |
| `densityGain` | table | A table containing information about density gain for all materials. |
| `positions` | table | A table containing all positions where voxels were added for each material. |