Seed Object

Plant seed object is the highest hierarchy level of a plant object. It builds a fractal plant using growth rules defined by its attributes and child objects (branches and leaves). The seed object includes a 2 point line geometry, which defines the initial growth direction and speed. All dimensions of the plant (branch diameters, leaf sizes etc.) are relative to the length of the line. Plants have some gravity related attributes, and the direction of the z axis (the blue object handle) defines the direction of the gravity.

The seed object generates the geometry of the plant under its own hierarchy. You can assign materials and constant attributes (color etc.) to the created plant hierarchy levels. Do not change the actual geometry items, because they are regenerated every time when a growth parameter changes and when loading a plant object from a file. If you need to edit the geometry items, move them away from the plant hierarchy.

Plant hierarchies. The simple hierarchy on the top grows the roots and the branches using the same rules. More complex trees use sub objects to define how trunk and branches grow.

To create a plant seed object:

  • Activate the Plant tool from the tool bar or from the pull down menu.

  • Click on a view window to define the point where the plant grows.

  • Move the mouse upwards to define the direction and speed of the growth. Click second time to finish the tool.

The plant tool automatically inserts a branch object into the seed object in order to set up a fully functional plant.

To change the direction of growth from the root, point edit the plant's axis line. Do not rotate the tree, because that would rotate the gravity direction as well. It is probably a good idea to make the generated plant geometry invisible while point editing the axis line.

Plant seed object includes the attributes described below.

Materials assigned to the tree geometry

Height: Controls the height of the plant. The value defines the approximate length of growth during the first year. The value is not exact because Random Length and other branch attributes contribute into the result.

Thickness: The thickness of the plant. The value defines the initial radius of the plant in the point where growing starts. Note that the branch profile and other attributes may change the radius from the value defined here.

Random Seed: Seed value for the computation of randomized plant properties. Change this to get unique trees.

Render Plus: Adds plant complexity for photorealistic rendering. The idea is to use easily manageable preview objects in the modeling stage and render the full detail only in the final images. The defined value is added to the plant's age, and the leaf density parameters are multiplied with (1+value). Because the number of branches usually grows exponentially by age, plant's complexity grows very rapidly at every render plus step. Usually a small value like 1 is enough; it typically increases the complexity by a factor of 8.

Max Complexity: Limits plant's complexity (number of branch segments + number of leaves) to a safe value range. Some attributes increase complexity exponentially. Mistyping a high value could rapidly consume all memory, cause heavy memory swapping and make it hard to recover from the error. The complexity limit protects you from this kind of troubles. The default value of complexity is a plant root's class attribute; use the preferences window to adjust it to match the performance of your computer system permanently.

Modeling vs. rendering complexity

Set UV: If set, the following information is stored into the tree geometry's UV Coords channel:

  • UV Coords.X - 0..1 parameter around the branch

  • UV Coords.Y - 0..1 parameter, which starts from zero at the root ends, and reaches 1 at the end of branches.

  • UV Coords.Z - the ratio (current branch radius/radius at the root)

A simple color gradient material

Set Colors: If set, the plant computes and stores colors for leaves and other items which include colorization features. Alternatively, the plant can be textured using materials in the plant hierarchy.