---
title: Rendering in FxPlug
framework: professional-video-applications
role: article
path: professional-video-applications/rendering-in-fxplug
---

# Rendering in FxPlug

## Rendering in FxPlug

Rendering in FxPlug Use Metal or other frameworks to render images with your FxPlug plug-in.

Overview

[FxImageTile](/documentation/professional_video_applications/fximagetile) is a new class for FxPlug 4 that combines and improves the frame information previously found in `FxRenderInfo` and `FxImage`, including bounds, pixel transforms, field and field order, and the image’s origin. Incoming images are now presented as an [IOSurface](/documentation/IOSurface), which is one of the biggest changes to FxPlug 4.

Rendering always involves these four steps:

1.     Gather the state your plug-in needs to render by checking parameter values and making calculations. [Communicating with the plug-in state](/documentation/professional-video-applications/communicating-with-the-plug-in-state) explains how to prepare required information for you plug-in to render. 2.     Tell the host application what the output area will be, given the input area. See [Set the destination rectangle bounds](/documentation/professional-video-applications/working-with-tiled-images#Set-the-destination-rectangle-bounds). 3.     For each tile of the output the host requests, tell it which tile of the inputs you need to render. [Working with tiled images](/documentation/professional-video-applications/working-with-tiled-images) explains how to set input and output bounds. 4.     Draw each output tile. See [renderDestinationImage(_:sourceImages:pluginState:at:)](/documentation/professional_video_applications/fxtileableeffect/renderdestinationimage(_:sourceimages:pluginstate:at:)).

When rendering, your plug-in will be given an [FxImageTile](/documentation/professional_video_applications/fximagetile) for output. Use this to return a texture to the host application when your plug-in has finished rendering. The `outputImage` contains a [deviceRegistryID](/documentation/professional_video_applications/fximagetile/deviceregistryid), which identifies what graphics card the texture is on. This is a read-only property.

For an example of how to work with [deviceRegistryID](/documentation/professional_video_applications/fximagetile/deviceregistryid), see the `FxDynamicRegistration` example. Specifically, look at `PAEMTLBrightnessRenderer.m`, in `renderWithBrightness` where the `OutputTexture` uses the `OutputImag`e’s `deviceRegistryID` value to create Metal state, and Input and Output textures.

> Note >  Your plug-in may suffer from a performance hit if you set [kIOSurfacePixelSizeCastingAllowed](/documentation/IOSurface/kIOSurfacePixelSizeCastingAllowed) on your IOSurface, so its use is generally *not* recommended. You set this flag to ensure that pixel locations are kept in order in VRAM, and then you can use custom pixel packing in your plug-in. If you do need this flag, when converting from 4:4:4 to 4:2:2 formats for example, the host app will provide a copy of the input and output IOSurface, so you can unpack your specific pixel format in the plug-in, and likewise pack your specific pixel format into the output [IOSurface](/documentation/IOSurface).