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Random Buildings: Difference between revisions
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(posting to docs: http://flightgear.org/forums/viewtopic.php?f=37&t=18935&p=175733#p175714) |
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[[File:Random-buildings.jpg|thumb|Random Buildings]] | [[File:Random-buildings.jpg|thumb|Random Buildings]] | ||
== The old Urban Shader == | |||
The old urban effect, even at minimum quality level, does a lot of texture reading. It needs to iteratively compute the intersection point of your view line with the heightmap, and so needs to read the heightmap quite a lot (if I remember correctly, it might need to read it up to 20 times - most 'normal' shaders read perhaps 1-5 textures). Texture read operations are generically expensive, more so on less powerful hardware. | The old urban effect, even at minimum quality level, does a lot of texture reading. It needs to iteratively compute the intersection point of your view line with the heightmap, and so needs to read the heightmap quite a lot (if I remember correctly, it might need to read it up to 20 times - most 'normal' shaders read perhaps 1-5 textures). Texture read operations are generically expensive, more so on less powerful hardware. | ||
So the urban effect has quite different demands on the GPU than other effects, and there is no reason it should scale like other effects - it is quite possible that it simply doesn't run fast enough on your machine. The urban effect is really a visual hack anyway, we'd strongly suggest leaving it off and using the new 'random buildings' feature instead, as described below: | So the urban effect has quite different demands on the GPU than other effects, and there is no reason it should scale like other effects - it is quite possible that it simply doesn't run fast enough on your machine. The urban effect is really a visual hack anyway, we'd strongly suggest leaving it off and using the new 'random buildings' feature instead, as described below: | ||
== The new System == | |||
As of 05/2012, FlightGear supports a new "random buildings" feature, buildings are generated at runtime and placed in Urban and Town areas. In v2.8.0 these take up a lot of memory, but in subsequent releases this has been improved significantly. | As of 05/2012, FlightGear supports a new "random buildings" feature, buildings are generated at runtime and placed in Urban and Town areas. In v2.8.0 these take up a lot of memory, but in subsequent releases this has been improved significantly. | ||