Compositing Tools
What are the Compositing Tools? The Compositing Tools are designed to simplify the process of combining simulated/rendered FLIP Fluids animations with real-world video footage.
The primary functionality revolves around advanced fading techniques, allowing the fluid and all particle types (such as foam, spray, and bubbles) to transition seamlessly into transparency. This ensures a more realistic and professional visual integration of simulations into live-action scenes.
These tools work behind the scenes by setting up complex shader and geometry node networks. The provided operators automatically build these setups, so users don’t need to spend time constructing custom node groups manually.
Depending on your workflow, you can either:
Render the final composited result directly, including all fade and integration effects, or
Split the effects into individual render passes, which can then be recombined and fine-tuned in a separate compositing step (e.g. using Blender’s Compositor or external tools).
A quick first video introduction can be seen in our Development Update Video:
The Compositing Tools were introduced in FLIP Fluids Addon version 1.8.3.
Since these tools rely on specific Shader and Geometry Nodes that were added in recent Blender releases, Blender 4.1 or higher is required to use the tools correctly. Please ensure that both your FLIP Fluids Addon and Blender installation are up to date before using the Compositing Tools.
Important: Always start with a fresh Blender scene in which no FLIP Fluids domain has been created (or deleted) before. Leftover data in memory from previously existing domains can cause unexpected behavior and conflicts.
The Compositing Tools panel is located at the bottom of the Helper Addon Panel in Blender's Tool Sidebar:
Before the full compositing interface becomes available, a guided initial setup routine must be completed. In just a few clicks, this routine automatically applies important simulation and render settings in the background, including:
- Activating required FLIP Fluids simulation attributes
- Enabling internal features needed for compositing
- Adjusting render settings for proper transparency and integration
You are free to modify the render settings afterward to suit your project.
Required Setup Steps (in order):
Start by creating a FLIP Fluids domain in the scene using the regular domain creation method:
This will execute the setup mentioned above – enabling attributes, activating features, and modifying render settings:
The CameraScreen is used to display and align your real-world footage in 3D space:
After clicking Add CameraScreen, a file browser will open. Here, you can load your footage – whether it's a single image, an image sequence, or a video file – to be used as background for blending your FLIP Fluids simulation with live-action content:
Once imported, the footage is stored in memory and becomes accessible to other compositing operations. For this reason, the footage import is considered an essential part of the initialization process.
💡 This also means that the frame range and resolution in Blender have been automatically adjusted to match the imported footage. The only thing you still need to verify manually is whether the FPS (frames per second) setting in Blender matches your footage. (The addon currently cannot read this information automatically.)
Once the CameraScreen object has been created, it acts as a virtual screen within the 3D scene. When rendering is enabled in the viewport, your loaded footage will now appear on this surface:
Surrounding the CameraScreen, you will notice a visible border – this is a special Fading Object.
Fading Objects are used throughout the entire compositing setup. They give users a powerful way to control the fade behavior of objects or simulation elements directly in the 3D viewport, without needing to touch any settings inside complex node networks. For the CameraScreen, this means that the edge fading of the footage can be easily adjusted interactively by scaling the border object:
💡 Why is fading applied to the CameraScreen? In some scenarios, the visible edges of the screen were reflected too prominently within the simulation (especially in reflections on the fluid >surface). Applying a subtle fade to the screen helps hide these edges and prevents this visual distraction – making the compositing look much cleaner.
The CameraScreen is automatically parented to the camera, ensuring it stays perfectly aligned during camera movement or animation:
This setup is especially important when working with tracked footage, where real-world camera motion is matched in the 3D scene – a standard workflow in VFX production. No matter how the camera moves or rotates, the CameraScreen will follow precisely, keeping the footage correctly positioned behind the simulation.
Once the initialization steps are completed, the full Compositing Tools interface becomes visible within the FLIP Fluids panel.
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