Worlds and physics

Build real 3D places you can walk through and film, bring a still backdrop to life, and make layers and models fall, bounce and break.

Walkable worlds

A walkable world is a whole place in real 3D: sculpted terrain painted in layers, thousands of trees, rocks, grass and flowers, buildings and rooms with real walls, doors, windows and stairs, water that reflects, and a sky that follows the time of day. Every tree, wall and rock is a model, so a camera can stand anywhere and parallax, occlusion and depth of field are always true.

Build a world

Worlds are built by the AI editor. Open it with ⌘ K on Mac, Ctrl K on Windows and Linux, and describe the place:

Build a misty pine forest at dawn with a small cabin and a stream.
Make a rainy city street at night, about 200 metres long.
Build a small two-room apartment with a sofa, a table and a bed.

You can start from a kind of place (forest, meadow, desert, mountains, island, canyon, arctic, village, city, interior or sci-fi) and ask for anything on top: the terrain (hills, plains, mountains, dunes, canyon, island, valley or flat), water (a lake, a river or the sea), trees, rocks and plants, buildings, roads, props, lamps and people who walk across the shot.

Build in layers, the way a set is dressed: the ground first, then big shapes (hills, a lake, buildings), then trees and rocks, then small things (bushes, grass, props), then light and fog. A forest with only trees looks like a plantation; add rocks, dead wood, clearings and a little fog. Keep things to human scale: a person is about 1.75 m, a door 2.2 m, a storey 2.8 m.

Change a world

Change a world rather than building it again. Select the world layer and open World settings in the Inspector. It lists everything in the world:

• Time of day, which you can keyframe to run a sunset or a whole day across a shot.
• Sky, Fog, Water, Terrain, Look, Quality and Start point. Click Set to add one the world doesn't have yet.
• Scatter, Buildings, Roads, Props, Characters, Lights, Sculpt strokes and Paint strokes: each item has its own settings and a Remove button, and the + beside each heading (Add one) adds a new item.

The world rebuilds when you let go of a control. You can also ask the AI editor for changes ("add a lamp by the cabin door", "make it dusk").

Sculpt and paint the ground

1. Turn on the 3D workspace with ⇧ Tab over the Player (see Scenes and models).
2. In the workspace header, open Terrain.
3. Choose a brush: Raise, Lower, Smooth, Flatten, Roughen, or Paint grass, Paint rock, Paint dirt or Paint snow.
4. Set the Size (in metres) and Strength, then drag over the ground.
5. Click Done when you have finished.

Walk through and film

1. In the 3D workspace, open View and choose Walk mode (⇧ ~).
2. Look with the mouse and move with W A S D. Hold ⇧ to sprint and press Space to jump. You walk on the ground, climb stairs and stop at walls.
3. Press V to switch to third person, and Esc to stop walking.

To turn a walk into a shot, choose View > Record walk, walk the route, then choose View > Stop recording walk. The path you walked is smoothed and keyed into a camera over the timeline. Fly mode (~) moves freely instead, without gravity.

The AI editor can also walk a route for you at a set speed (a stroll is 1.2 to 1.6 m/s, a run 3 to 4), pause where something happens, keep a subject in view, or place a camera where a person would stand. It can check first whether a route is walkable, so a camera never ends up inside a hill or behind a wall.

A quick 3D set

For a simple outdoor set without building a whole world, select a 3D model and use the World section on the Advanced tab: Sky at golden hour, Hills with trees, Mountains or Ocean. A sky light's Sky section then sets the Time of day, Haze and Hazy air.

Living places

A generated or painted backdrop is a still picture. Zornov can make each part of it do what it would in life, while the ground holds still.

Ask the AI editor to bring a backdrop to life. It reads what the picture is made of (sky, water, ground, trees, rocks, where the light comes from) and moves each part only inside its own area:

• Water: ripples flow along it and glints dance on it.
• Foliage: trees and plants sway.
• Clouds: wisps drift across the sky.
• Rays: light rays from the brightest part of the sky breathe slowly.
• Weather and time: rain, storm (heavier, with wind and lightning), snow, leaves, dust, embers, magic, fireflies, mist or fog, dusk, night, day to night or night to day.

Weather and changes of light can ramp in over a few seconds, so a storm arrives as the trouble starts. Each effect is its own layer, named for what it does, so you can adjust or remove it like any other layer. Keep it subtle unless the moment is about the weather.

To add one particle effect by hand, click 3D camera and lights on the Player toolbar and choose from Particles: Rain, Snow, Falling leaves, Dust motes, Fireflies, Sparks, Smoke, Mist, Splashes, Bubbles, Confetti, Magic dust, Clouds, Glints, Stars or Embers. It goes on a new layer at the playhead, and its settings (amount, size, speed, wind and more) are in the Inspector under Effects.

A place feels real when it also sounds real: give it a bed of wind, rain, birds or water under the voices. See Sound effects and voices.

Physics

Physics runs once and is kept: the result becomes ordinary keyframes (and pieces, for things that break), so you can scrub, cut and render without simulating again. Running it again replaces the earlier result.

Drop 2D layers

1. Place the layers where they start: above the frame, tilted a little.
2. Select them and open the Physics section on the Animation tab.
3. Set Bounce, Friction and Run for (seconds). Frame edges keeps them inside the sides of the frame; Round makes them roll like balls.
4. Move the playhead to where they should fall and click Drop from the playhead.

They fall to the bottom edge, bounce and settle. Piles look real when the pieces differ: start them at different heights and angles. Use a low bounce (20 to 40 %) for paper and cards; save high bounce for balls.

Simulate 3D models

Select a 3D model and open the Simulation section on the Animation tab:

For full control, open Simulation settings on the Model tab, choose a Simulation (Drop and bounce, Shatter, Cloth, Jelly, Hair and fur, Particles, Smoke, Fire, Pond or Ocean), set its values and click Bake. Cloth can be a cape, flag, curtain, tablecloth or banner, in cotton, silk, denim, leather or wool. Reset settings goes back to the automatic values.

To see the shapes that collide, open View in the 3D workspace and turn on Physics colliders under Show.

More physics with the AI editor

The AI editor can set up whole physical scenes. Ask it in plain words, for example "knock over the stack of boxes with the ball" or "the vase falls off the table and shatters". It can:

• Say what each thing is made of. The material sets its weight from its real volume, how much it grips and bounces, and whether it breaks: wood, steel, glass, porcelain, ceramic, ice, stone, rubber, foam, paper, cardboard, fabric, leather and many more. Glass, porcelain, ceramic, ice and plaster shatter when hit hard.
• Join things: a hinge for a door or a lid, a rope, chain or spring for something hanging, a slider for a drawer, or glue two things together. Joints can be set to snap.
• Drop, throw (so it lands on a target), push, or break something, or simulate the whole scene from the playhead.
• Make a character go limp and fall (ragdoll), or stagger when something hits it hard.
• Add follow-through: tails, ears, antennae, ponytails and coat tails that keep moving after the body stops.
• Settle anything that floats above, sinks into or tips off what it stands on.

Gravity is real, so the scale of the scene matters: people are about 1.7 m tall. Tell the AI editor if the scene is a toy table or a whole city.

Related pages

• Scenes and models
• Lights and cameras
• Animation and puppets
• The AI editor