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WorldOccluderTerrain Class

Terrain occluder introduces a cheaper and more efficient way of handling intersections with terrains. The objects behind the terrain occluder are not sent to the GPU, which saves performance.

Notice
If terrain relief is changed in the runtime, it is not recommended to use the occluder.

Usage

To provide increased performance, terrain occluders should be used wisely.

  • A terrain occluder can be a great benefit in case of mountains or complex urban environments.
    • If a terrain is flat, occluder can reduce FPS since there are no surfaces that can be culled.
    • On the contrary, an occluder is highly effective if there are many objects that are costly to render (they have a lot of polygons and/or heavy shaders). However, these objects should not be too large since if any part of their surface is seen, it cannot be culled.
  • When the camera is high above the ground (for example, for flight simulators), an occluder should be disabled. At the same time, when it is near or on the ground (during a takeoff or landing), occluders can be enabled to provide performance gain.
  • If terrain relief is changed in the runtime, it is not recommended to use the occluder.

Generation

The terrain occluder is generated basing on its downsized height map using cone-step mapping. Generation of an occluder texture is a time-consuming operation that should be done only once rather than each time on world load.

To set a texture for WorldOccluderTerrain in real-time, use the following steps:

  1. Set a height map texture (in R8, R16 or RG8 format) via setHeightsImageName(). Cone-step mapping will be calculated and a new image (in RGB8 format) will be generated. It contains all data necessary to perform occlusion.
  2. Get newly generated occluder image (RGB8) via getHeightsImage().
  3. Save this occluder image (RGB8) to disk with same name.
This way there will be no need to perform time-consuming cone-step recalculation the next time a world is loaded.

WorldOccluderTerrain Class

This class inherits from Node

Members


WorldOccluderTerrain (vec3 size)

Constructor. Creates a new terrain occluder of the specified size.

Arguments

  • vec3 size - Size of the terrain occluder in units.

float getDistance ()

Returns the current distance for disabling terrain occluder.

Return value

Distance in units.

string getHeightsImageName ()

Returns the name of the height map that repeats terrain heights.

Return value

The name of the height map.

Image getHeightsImage ()

Returns the height map image that repeats terrain heights.

Return value

Height map image.

float getRadius ()

Returns the current ray tracing radius to perform occlusion. The default is infinity.

Return value

Radius of occlusion in units.

vec3 getSize ()

Returns the current dimensions of the terrain occluder.

Return value

Size of the terrain occluder in units.

void setDistance (float distance)

Sets the distance for disabling terrain occluder. The default is infinity.

Arguments

  • float distance - Distance in units. If a negative value is provided, 0 will be used instead.

int setHeightsImageName (string name)

Sets the name of the height map that repeats terrain heights. The height map can be smaller in size compared to terrain's one. It will be automatically converted into the RGB8 format.

Arguments

  • string name - Height map name.

Return value

1 if the height map was successfully loaded; otherwise, 0.

void setRadius (float radius)

Radius of ray tracing to perform occlusion. The radius is counted off starting from the camera.

Arguments

  • float radius - Radius of occlusion in units.

void setSize (vec3 size)

Sets the dimensions of the terrain occluder. The default is vec3(1.0f).

Arguments

  • vec3 size - Size of the terrain occluder in units. If a negative value is provided, vec3(0.0f) will be used instead.
Last update: 2017-07-03