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Durk Talsma 2011-09-12 19:52:03 +02:00
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Docs/README.3DClouds
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@ -32,34 +32,41 @@ by a OpenGL Shader - a small program that is run on your graphics card.
The cloud is defined by the following properties:
<min-cloud-width-m> - minimum width of the cloud in meters (default 500)
<max-cloud-width-m> - maximum width of the cloud (default min-cloud-width-m)
<min-cloud-height-m> - minimum height of the cloud (default min-cloud-width-m)
<max-cloud-height-m> - maximum height of the cloud (default max-cloud-width-m)
<max-cloud-width-m> - maximum width of the cloud (default min-cloud-width-m*1.5)
<min-cloud-height-m> - minimum height of the cloud (default 400)
<max-cloud-height-m> - maximum height of the cloud (default min-cloud-height-m*1.5)
<texture> - texture file of sprites to use (default cl_cumulus.png)
<num-textures-x> - number of cloud textures defined horizontally in the
texture file (default 4)
<num-textures-y> - number of cloud textures defined vertically in the
texture file (default 4)
<height-map-texture> - whether to choose the vertical texture index based on
sprite height within the clouds (default false)
<num-sprites> - Number of sprite to generate for the cloud (default 20)
<bottom-shade> - Light multiplier for sprites at the bottom of the cloud
(default 1.0)
<min-sprite-width-m> - minimum width of the sprites used to create the cloud
(default 200)
<max-sprite-width-m> - maximum width of the sprites used to create the cloud
(default min-sprite-width-m)
(default min-sprite-width-m*1.5)
<min-sprite-height-m> - minimum height of the spites used to create the cloud
(default min-sprite-width-m)
(default 150)
<max-sprite-height-m> - maximum height of the sprites used to create the cloud
(default max-sprite-height-m)
(default min-sprite-height-m*1.5)
<z-scale> - vertical scaling factor to apply to to the sprite after
billboarding. A small value would create a sprite that
looks squashed when viewed from the side. (default 1.0)
The texture to use for the sprites is defined in the <texture> tag.
To allow some variation, you can create a texture file containing multiple
sprites in a grid, and define the <num-textures-x/y> tags. The code
decides which texture to use for a given sprite : randomly in the x-direction
and based on the altitude of the sprite within the cloud in the y-direction.
Therefore, you should put sprite textures you want to use for the bottom of
your cloud at the bottom of the texture file, and those you want to use for
the top of the cloud at the top of the texture file.
and based on the altitude of the sprite within the cloud in the y-direction
if <height-map-texture> is set. Therefore, you should put sprite textures
you want to use for the bottom of your cloud at the bottom of the texture
file, and those you want to use for the top of the cloud at the top of the
texture file.
For example, the following Nasal snippet will create a cloud immediately above the
aircraft at an altitude of 1000 ft above /environment/clouds/layer[0]/elevation-ft :
@ -92,14 +99,14 @@ Deleting Individual Clouds
Clouds may be deleted by using the "del-cloud" command. This takes the following
property arguments.
<layer> - The cloud layer number containing the cloud to delet. (default 0)
<layer> - The cloud layer number containing the cloud to delete. (default 0)
<index> - The unique identifier of the cloud to delete.
Global 3D Clouds
================
The global weather system uses sets of clouds defined in cloudlayers.xml
in your FG_ROOT.
The global weather system uses sets of clouds defined in
FG_ROOT/Environment/cloudlayers.xml
The file has 3 distinct sections: layers, cloud boxes and clouds,
described below.