I am trying to use Depth and Sun positions. I am using and HDRI/Blender Sky. I don't have a sun lamp, how do I go around that?
Add a sun object, add it some intensity so you can see shadows. Rotate the object to align the shadows to the World Lighting. Once aligned - turn the intensity to zero and use it to simply guide the addon.
Something broke after updating. What should I do?
Check for the supported versions on the addon page. It might be the addon has not been updated to the most recent version of Blender yet. Supports 5.0 and Most recent 5.1 release
Are you planning to update the addon? Will it work with future versions of Blender? Will there be bug fixes?
Yes. Real Caustics will be actively supported after release.
Expect bug fixes, compatibility updates, and new features over time.
Expected features for new version:
- Expand compatibility with Blender 4
- Depth-aware caustics
I have an idea that could make the addon better. Can I share it?
Absolutely. Join the Discord group and post your suggestion there. All ideas go through evaluation, and if it's a good fit you may see it land in a future update.
I ran into a problem with the addon. Can I get some help?
Yes. Join the Discord group and report your bug or issue there. We will do our best to identify the problem and find a solution together.
Everything is set up correctly but some objects in my collection are not generating normals. Why?
Make sure there are no nested collections inside your Water Collection — only direct object members are supported. Collection instances will not work either. All water objects must be placed directly inside the collection, not grouped within sub-collections.
What does Preserve Displacement do?
When enabled, the addon reads your shader-based Displacement and Bump maps during generation, so the caustics follow the generated normals of the water rather than the base mesh. You can achieve the best results when your simulation generates real geometry and your shader bump generates smaller details waves.
Can I use Real Caustics on the water surface itself, not just the geometry below?
Yes. The Caustics Parallax node projects the caustic texture directly onto the water surface using parallax offset, simulating the appearance of caustics cast on geometry below the surface. This feature is currently experimental. Best results are when applied to a completely flat plane
My caustics don't align with the water surface. What's wrong?
Make sure the Caustics Projection node is connected to a Texture Coordinate node set to Object, pointing to the Caustics Camera. Also verify the camera is orthographic and correctly framing the water surface. If the Camera is perspective - use Texture coordinate Window set to Window or UV projection setup.
I accidentally started Generate Sequence. How do I cancel?
Simply press ESC.
How long does generation take and what resolution should I use?
A single preview frame generates in seconds. Full sequence generation at 2048 resolution runs at approximately 4 seconds per frame, though this varies depending on your hardware and quality settings. 2048 tends to be a good balance for final renders. Be careful when combining high resolution with high Substeps or Bilinear Sampling — this can fill memory quickly and may freeze Blender. Start with lower settings and gradually increase until you find the right balance between speed and quality.
Do I need dense geometry for the caustics to look good?
No. Real Caustics traces light using your shader's Displacement and Bump maps directly, so the visual result is independent of mesh density.
What surfaces and objects does it work with?
Real Caustics is designed and optimised for water surfaces — fluid simulations, ocean modifiers, dynamic paint outputs, and any mesh-based water geometry. While it can produce interesting results with other glass objects, it only accounts for a single ray pass. There are no internal bounces, depth variation, or IOR changes as rays are traced through the geometry. For realistic glassware and gemstone caustics, standard path-traced methods will give more accurate results.
What render engine does Real Caustics work with?
Real Caustics generates caustic textures using both Cycles and EEVEE. Since the output is a baked texture, it can be used in any render engine. If you are working in a USD pipeline, you can generate the textures in Blender and bring them into your software of choice. For custom engine integration, refer to the architecture of the Caustics Projection and Energy Fix nodes and use them as a reference to rebuild the setup in your target engine.
Sergei Zakharov
Included