# Particles Spacer


*Particles Spacer* is a volumetric field that has no visual representation, but physically interacts with [Particle Systems](../../../../objects/effects/particles/index.md) (other objects are not affected). The *Particles Spacer* is used to cut out particles generated by a Particle System from a certain volume, for example, to avoid rendering of rain or snow inside a car or under a bridge. It can have a box, cylinder, capsule, sphere, or ellipse shape and can be arbitrarily positioned or rotated to cover the necessary area.


![](spacer_off.jpg) ![](spacer_on.jpg)


### See also


- The *[ParticlesFieldSpacer](../../../../api/library/objects/class.particlesfieldspacer_cpp.md)* class to manage *Particles Spacers* via API


## Adding Particles Spacer


To add a *Particles Spacer* to the world via UnigineEditor, do the following:


1. In the Main Menu, choose *Create -> Particle System -> Particles Spacer*. ![](add_spacer.png)
2. Place the *Particles Spacer* in the world to cover the area where particles are to be cut out: > **Notice:** Make sure that the *Spacer interaction* flag is set for materials applied to grass or water.


## Editing Particles Spacer


In the *Particles Field Spacer* section (*[Parameters](../../../../editor2/node_parameters/index.md)* window -> *Node* tab), the following parameters of the *Particles Spacer* can be adjusted:


![](edit_spacer.png)


### Adjusting Spacer Form


| Shape Type | Shape of the *Particles Field Spacer*: *box, cylinder, capsule, sphere*, or *ellipse*. |
|---|---|
| Size | Size of the *Particles Field Spacer* along the *X, Y*, and *Z* axes, in units. > **Notice:** In case of an *ellipse* shape each component of the vector sets a radius along the corresponding axis. |
| Radius | Radius of the *Particles Field Spacer*, in units (available for *capsule, cylinder*, and *sphere* shapes). |
| Height | Height of the *Particles Field Spacer*, in units (available for *capsule*, and *cylinder* shapes). |
| Interaction Particle Mode | Interaction mode for the *Particles Field Spacer*. Interaction can be triggered on a contact of the spacer either with particle's center position or with its bounding box (this can be useful in case of length particles, for example). |


### Setting Bit Masks


Bit masks listed below enable you to fine tune interactions and functionality of a *Particles Field* to achieve the desired effect and optimize performance.


| Particles Field Mask | Bit mask enabling you to control interactions of the *Particles Spacer* with particles. The *Spacer* will affect particles generated by a Particle System only if they both have [matching masks](../../../../principles/bit_masking/index.md). |
|---|---|
| Viewport Mask | A *Viewport* mask. A bit mask for rendering the *Particles Spacer* in the current viewport. For the *Particles Spacer* to be rendered into the viewport, its mask should match the camera *[Viewport](../../../../principles/bit_masking/index.md#viewport)* mask (at least one bit). This can be used to selectively disable *Spacer* functionality for a certain camera view without disabling the *Spacer* itself (e.g. it is not necessary to cut out rain or snow inside a car, when the car is viewed from above). |