Difference between revisions of "Populator v3"

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[[Category:Population Nodes| ]]
[[Category:Population Nodes]]

Revision as of 18:48, 1 June 2011

Populator v3[edit]

Populator v3.01

Additional tabs for Populator v3[edit]

Node Description & Purpose: The Populator is used for creating and distributing many instances of the same object across a customizable rectangle area on the xz-plane. By using the Populator, the user can have the application accurately place instances of objects (instantiated objects) on the terrain surface automatically, so that the object's y coordinate matches the y coordinate of the terrain. The ability to specify a density shader allows users to mask the placement and distribution of objects. If no distribution shader is specified, the Populator places objects randomly across the define rectangle area. To mimic more variety, the Populator can rotate instantiated objects randomly around the y-axis, and vary the object scale within a Population by user defined parameters.

Node Type: Population (of any object type)

Nodes in Default Scene: n/a

Settings - Main: Settings on main settings window (outside tabs)

  • Name: The name of the populator node
  • Enable (Checkbox): Enables or disables the Populator.
  • Show b-box in preview: Enables or disables a 2D rectangle in the preview window, which marks the boundaries of the population on the xz axis.
  • Object maker: Allows to enter or select an object maker that defines the object being populated.
  • Unique Variations: Not yet functional.
  • Render Quality: Allows for specifying the render quality of populated objects. To reduce render times, level-of-detail reduction is applied to parts of objects that appear very small in the rendered image, with respect to the image resolution and detail settings in the render node. Therefore more detail reduction is applied to objects in the distance or to objects with very small polygons. The Render Quality setting controls how much reduction takes place, but also affects render times.
  • "Populate Now" Button: Calculates a population of instanced object based on the current settings. If you do not press this button, the population will be calculated automatically the next time you render an image, but if you have enabled "Preview instances" then you can use this button to preview the positions of the objects in the 3D Preview without rendering an image.
  • Repopulate every frame: Forces the populator to recalculate the positions and sizes of the instantiated objects every time a new frame is rendered. This is necessary if you animate your distribution functions, terrain, or object maker. If you don't check this box, the population will still be calculated automatically at the start of a render if any of the Populator's parameters have changed.
  • Preview Instances: Enables or disables object preview in the preview window. Objects can currently not be rendered in the preview, but Terragen 2 draws a 3D box around each instantiated object. This can slow down navigation in the preview window drastically with very large numbers of instances, hence the checkbox allows users to temporarily switch of drawing those 3D boxes in the preview.

Settings - Tabs:

Distribution Tab:

  • Area Centre: Enter the 3D coordinates of the rectangle distribution area on the XZ plane and the Y value for height. Leave the Y field empty if you rather want to specify a terrain onto which the objects should be placed.
  • Area Length a: Length of one side of the population boundaries (along x).
  • Area Length b: Length of one side of the population boundaries (along z).
  • Object Spacing: Specify the average distance from one object instance to the other.
  • Use density Shader: If left empty, the Populator will randomly, but completely cover the specified area with instantiated objects. You may create or select an existing shader to serve as a mask for the populator instead (such as a power fractal shader, or an image map projection.
  • Invert Density Shader: Inverts the mask specified in the density shader.

Terrain Tab:

  • Sit on terrain: Mark the checkbox AND specify a shader to serve as a terrain onto which the instantiated objects will be placed.

Object Scale Tab:

  • Minimum & Maximum Scale: Defines the minimum and maximum multiplier affecting the size of an instantiated object. The default size of an object in the population is defined in the corresponding object maker. The "minimum & maximum scale" setting allows to redefine the range of scales within the population, relative to the default size in the object maker.

Object Rotation Tab:

  • Minimum & Maximum Y Rotation: Defines the minimum and maximum angle in degrees by which the populator may rotate the instances alround the y-axis.

A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.

A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.