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Ogre Terrain System         Embed terrain to an Ogre application
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In 2009 sinbad (founder of Ogre) started to create a new terrain system. It replaces the old Terrain Scene Manager and includes ideas of other terrain addons, key of which is being a component system which can live within any SceneManager rather than being one itself. Since Ogre 1.7 the new Ogre Terrain Manager is an Ogre component.

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Features

  • SceneManager independent, separate optional component (OGRE_HOME/Components/Terrain)
  • Integrates with (optional) Paging component
  • Inherently editable - a lot like ETM
  • Hierarchical geometry batching: batch count reduced at lower LODs as well as vertex count. At the lowest level of detail, the entire terrain page is a single batch which has obvious advantages for large paging terrains over the fixed tiles previously used. There is also the possibility to go to a lower overall resolution and to drop detail geometry in the far distance compared to non-hierarchical approaches.
  • Skirts are used instead of stitching to avoid cracks in geometry. This means fewer indexing arrangements and lower overall index buffer usage
  • In-built support for splatting layers, configurable sampler inputs and pluggable material generators
  • Support for generating global normal maps and light maps in a background thread
  • Saving & loading of terrain built in, including loading / processing in a background thread
  • LOD now adapts in real-time to camera settings (viewport sizes & LOD bias) so you can use the same terrain with multiple views efficiently


The Terrain System can be used in combination with the Paging Component.
Features of the Paging Component:

  • SceneManager-independent, separate optional component (OGRE_HOME/Components/Paging)
  • Pluggable strategy components to control paging strategy for a section of the scene
  • Pluggable content components to control paging of content
  • Plugggable collection components so that paged elements can be composed or selected between in different ways (e.g. paging many LOD levels within a page)


The Terrain System requires the CgProgramManager plugin to function correctly.

Using Ogre Terrain


Basic Tutorial 3 shows how you can use this terrain system.

Some definitions:

  • Ogre::Terrain = a small group of tiles, lets say 256x256
  • Ogre::TerrainGroup = a group of Terrains, there is no actual limit of how many terrains it can have. The Terrains hardware limit is the number of Ogre::Terrains visible/in memory.
  • Ogre::TerrainPaging = A wrapper to add/remove predetermined Ogre::Terrains on the fly (so you may have lets say 1000 Ogre::Terrains in a TerrainGroup but only the 9 of them around the player is visible at once)
  • PagingManager = general purpose paging handler, not limited to terrain but also supplies functions to page other elements in the scene.


How paging interacts with terrain:

If you are not using paging:

  • All terrains you add to a group are loaded.


If you are using paging:

  • All terrains in the radius LOADRADIUS, centered around the current camera position, will be loaded.
  • Terrains already loaded in the radius HOLDRADIUS will be kept in memory.

Video

This video shows the Ogre Terrain Component in association with the Ogre Paging Component.

See also

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