Rendering
Rendering a bake: motion blur on particles, shapes, liquid and smoke; why Persistent Data is turned off; animation renders; and render farms with Collect for Render.
A bake renders as it plays: press F12 for a still, or Render ▸ Render Animation for the shot. Renders always show every particle, whatever Viewport Share says, and Render Multiply's copies.
Motion blur
Turn on Motion Blur in the render settings. VecFlow gives each thing what the render engine needs for it:
- Spheres and shapes blur in Cycles and EEVEE.
- The liquid's surface blurs in Cycles, by its vertices' motion.
- The smoke volume blurs in Cycles, along the gas's velocity.
The streaks are the right length even when particles are born, die or change order between frames. Between frames each particle moves along its velocity, so the blur is straight.
Keep the Shutter at a frame or less with its position at Center, the default; at Start or End, half a frame or less. A longer shutter reaches past the frames it can blur between.
Persistent Data
While a render runs with VecFlow objects in the scene, VecFlow turns Cycles' Persistent Data off, and turns it back on after. With it on, Cycles (OptiX most of all) now and then keeps one frame's mesh for the next, and a piece that has come to rest is drawn where it was some frames before, then jumps.
On a computer without VecFlow, nothing turns it off: turn Persistent Data off in the file yourself before you send it.
Only baked frames render
Outside the baked range the particles object shows nothing, so a render past the bake's end loses the simulation. Check the status box says the whole range is baked, and that a background bake has finished, before rendering the shot.
Hide what shouldn't render. The starters hide a fire's or smoke's particles object (only the gas shows) and a liquid's fill mesh; a liquid's particles never show, only its surface.
On another computer, or a farm
Collect for Render, in the Bake Settings panel, saves a copy of the file into a folder you pick, with every bake it plays beside it:
- the folder renders on any computer with Blender, even one without VecFlow: the playback only reads the bake's files;
- retiming plays the same there;
- state saves are left out: they're only for carrying a bake on;
- the open file is left as it was;
- it can't run while a background bake is going: wait for it to finish.
Copy the whole folder to the farm and render the .blend in it. See the cache folder.
What goes wrong
- A resting piece jumps now and then. Persistent Data was on: on a computer without VecFlow, turn it off.
- The render shows nothing past a frame. The bake stopped short of it: Continue it.
- The farm renders no simulation. It's rendering the original file, not the collected copy, or the copy's folder wasn't sent whole.
Related
Retiming a bake
Play a bake later or earlier, in slow motion, held, or backwards, and ramp between speeds with keyframes, all without a new bake.
Using values
Recipes for values each particle carries: count bounces and change on the third, give each particle its own weight, colour particles in a shader by a value, and check a value at a frame.