Plants and forests

A plant in Omnion isn’t a fixed model: it’s a stack of levels (trunk, branches, twigs, leaves, flowers…) that the engine grows from a seed. Change a number and the plant grows again; change the seed and you get another plant of the same kind. Plants sway in the wind, cast shadows through their leaves, get simpler with distance and turn into flat photos far away, so a forest of twenty thousand plants still runs smoothly.

Make a plant

+ New › Plant in the Content Browser makes a .plant.json and opens it in the Plant Editor: the plant on the left, its settings on the right.

• Start From gives a species to begin with: oak, pine, birch, willow, palm, bush, fern, grass, reeds, flowers, cactus, sapling, fruit tree, bramble, mushroom and ivy.
• Scanned Species are the same kind of plant with real bark and leaves (CC0 images that come with the editor).
• Randomize invents a whole plant. Natural keeps it believable; Wild allows any shape and color.
• New Seed keeps the plant and grows another one of the same kind.
• Preview Wind moves the plant in the view only.

Drag in the view to turn it, use the middle button to pan and the wheel to zoom.

Levels

Each level grows on the stems of the level above it. + Stems, + Leaves and + Flowers add one; the arrows reorder them and the cross removes them. Pick a level to change it:

• Count, Start and End: how many, and where along their parent they grow.
• Angle, Length, Falloff, Radius and Gravity: how they leave the parent, how long and thick they are, and how much they droop (negative lifts them).
• Size and Width for leaves and flowers, and Variation for how different each one is.
• Curves: Thickness along each stem (base to tip), and Length by Height or Size by Height, by where they grow on the parent. A pine with long branches at the bottom is one curve.

+ Roots adds roots at the foot of the trunk. They grow out and down into the ground, and nothing grows from them: the next level still grows from the trunk.

Look

• Color tints the shape, the bark or the image.
• Shape: tube or ribbon for stems; leaf, round, blade, needles or thorn for leaves; petals, daisy, bell, fruit or mushroom cap for flowers.
• Image: drop your own picture of bark, a leaf or a flower from the Content Browser. Leaves and flowers should stand upright with their stalk at the bottom. Make Cutout removes a plain background and saves a copy with transparency.
• Material: drop a node material instead of a color and an image. The wind still moves it.

Images with transparency also work on any object: drop one on a plane and it becomes a cut-out, two-sided material whose shadow has the shape of the picture.

Hand edits

Click a branch in the Plant Editor view to pick it. Hand Edits can remove it, Bend it, Turn it around the stem it grows from or change its Length. Everything that grows from it moves with it, and the edit stays on that branch even if you change the levels later. Reset All Edits gives every branch its normal shape back.

Put plants in the level

Drag a plant file into the viewport. Each copy gets its own seed, so two copies are never the same. In Details:

• Seed and New Seed pick another plant of the same kind.
• Trunk Collides makes the trunk solid when you play.
• Edit Plant opens it in the Plant Editor. If it comes from a file, Save there updates every object that uses it.
• Make Unique gives the object its own copy of the plant.

Climbing plants. Levels with Climbs turned on (ivy has it) grow over walls, rocks and the ground. Put the plant next to them and press Attach to Surfaces in Details: the editor finds the surfaces around it and the stems grow up over them. Do it again after moving the plant or what it climbs on; Detach lets it grow on its own again.

Paint a forest

Add a Foliage component to an object (the ground or any empty object), then in Details:

• + Add Plant picks the plants to paint: your files, the scanned species or the built-in ones.
• Paint turns the brush on. Drag over the terrain or any surface to sow plants; hold Shift to erase. Brush Size sets its radius.
• Each plant has its own Density, Size, Max Slope (steeper ground stays bare), Follow Ground (how much it leans with the slope) and Trunks Collide.

A stroke is one step of Ctrl+Z. Update from File brings in changes made to a plant file.

Wind

World Settings › Wind sets the Direction, Strength and Gusts of the level. Gusts roll across the level like waves. Each plant has a Flexibility in the Plant Editor: grass bends a lot, trunks very little, a cactus not at all.

Far away

Plants get simpler with distance and fade from one level of detail to the next. Trees switch to an impostor: the tree photographed from eight sides, shown on a card that turns to the camera, with its own lighting and shadows. Grass and small plants stop being drawn when they’re too small to see. In a painted forest, only the plants near the camera are full meshes. All of this is automatic.

Plants and AI

+ New › Generate with AI… › Plant writes a plant from a description, and Change with AI… in the Plant Editor changes the one you’re editing. The engine grows each answer and checks it before showing it. Through the MCP, Claude can also place plants and paint forests. See Working with AI.

On the web

Plants and forests work in web games too. As with any web game, the browser compiles its shaders during the first minutes, so the frame rate is uneven until it finishes.