Viewport Object Distribution

Viewport object distribution is under active development, so this feature might change in the future.

Viewport objects are a little different compared to other distributable elements in LightAct because they can only be Ran on one single machine. However, you can still choose which machine to run a Viewport object on.

Good to know: Using the distribution system for Viewport objects reduces Video RAM usage and consequently improves machine performance in LightNet clusters.

Run on property

You can find the Run on property of a Viewport object by opening the Properties window and selecting the desired object on the Viewport. In its Properties, under the General section, you will notice a drop-down menu named Run on.

As a general rule, an object will render its mapped texture with full quality only on the machine it Runs on. All the other machines in the LightNet cluster will render the down-sampled version of the texture, determined by the FBO Downsampling value. Because of this, all the other machines in the cluster will perform better.

Viewport objects which support this feature are: video screens, throwers and projectors. In the continuation of this chapter, we will present an example for each of these Viewport objects.

Video screens

In order to visualize the function of the Run on feature, we will output content on our Video screen. If the Video screen Runs on the machine we are operating on, in our Viewport, the content on the screen will render with full quality.

On the other hand, if the Video screen Runs on another machine, in our Viewport, the content on that same Video screen will be seen with a down-sampled quality.


Using the Run on feature for Throwers provides similar results as using this feature for Video screens. To visualize it, we are going to output content from a Thrower to a Video screen. When the Run on machine is the one we are operating on, then the content outputted from the Thrower is rendered with full quality.

If the Thrower Runs on another machine, then in our Viewport, we will notice a down-sampled version of the content being outputted.


The Projector object in LightAct is generally used as a representation of a physical projector. Because of this, the machine on which the physical projector is connected to, should be the machine the virtual projector Runs on. For example, if my physical projector is connected to the machine I am operating on, then the virtual projector will also be set to Run on my machine.

If the physical projector is connected to another machine in the LightNet cluster and the virtual projector Runs on that other machine, my machine will 'see' a down-sampled texture.

Good to know: This system works best when used in combination. For example you may have a Thrower outputting content to a Video screen and a Projector which has that Video screen as its source. In this case, you probably want all those three objects to run on one single machine, otherwise you risk down-sampling the outputted content which probably isn't your intent.

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