Greybox first, render second: Blender previs is becoming the steering wheel for Seedance, Kling and H3

Prompting camera moves is still guesswork in every major video model. More teams are solving it by not prompting the move at all. You block the scene in grey shapes, animate the camera the way you would in previs, and hand that clip to the model as a motion reference. A style frame or prompt then sets the look. The greybox decides where things go and the model decides what they look like.

The open-weights version is SolarRenderer from Enderfga (about 300 stars, code, weights, data and benchmark released this month). Per the README and paper, it takes almost any structure video, including a game-engine greybox, segmentation map, skeletons, depth, a body mesh or a pencil storyboard it never saw in training, and renders a finished clip on MiniMax H3 with two LoRAs in four steps. The authors claim 12.3× faster sampling than 50 steps and offer a streaming mode that shows the video block by block. There's a free Hugging Face demo if you want to see results before setting anything up.

The Blender version arrived today. Scenario's open-source Blender plugin (GPL-3.0, Blender 5.0+, marked experimental) puts its image, video, 3D, PBR and audio generation in the sidebar. Its Oct 26 post shows a Blender camera move coming back as a Seedance 2.5 shot. It also has a Blockout tool that turns a written scene description into a greybox layout, plus a local MCP server. Generations cost Scenario credits and the plugin needs an API key, so it is free to install, not free to run. Polypro posted the same idea as a split screen: a greybox built through the Blender MCP, a style frame in Nano Banana 2.1, then Seedance 2.5 using the previs as motion reference, with the same three shots and the same timing.

Creators are getting there too. Veerapatra Jinanavin's 'TEA BREAK' making-of shows a Blender layout pass driving a Seedance 2.5 action short, and Layer's video goes from grey blockout to a finished game shot with Kling 4. If you'd rather skip Blender, CozyClay (in our directory) does greybox sets, posed characters and dolly moves in the browser with no GPU, then exports first/last frames and a reference clip per target model. For agent-driven Blender work, EL4CTEO's blender-skills pack (MIT, 22 skills for Blender 5.2, about 500 stars) covers modeling, rigging, animation and export.

Our take: for shots where the camera move matters, like product orbits, chases and game trailers, a five-minute greybox will probably save more regenerations than any prompt trick. Start with CozyClay or the SolarRenderer demo, which cost nothing. Use the Scenario plugin if you already work in Blender and want Seedance in the sidebar.