> Hi All,
> Having seen some recent screenshots from X-Plane 10, I've been
> thinking about ways to improve our random scenery, in particular
> buildings.
> At present, we have random building scattered over the scenery, based
> on .ac models, plus the Urban shader.
> The former are limited in that performance suffers significantly as
> density increases, and there is little control over their placement.
> The Urban shader provides an good impression of a complex city-scape,
> but the sides of the buildings are rather gray, and the visuals suffer
> at low viewing angles. It also has a significant performance impact.
> I'm wondering whether there is any mileage in using a variant on the
> scheme we use for random vegetation to create a cityscape. As you may
> be aware, the random vetegation uses a small number of geomerties
> instantiated all over the terrain, and uses a vertex shader (which is
> much cheaper than a fragment or geometry shader) to provide height,
> width and texture information.
> Of course, there's no point at all in doing this unless it provides
> better performance than the urban shader.
> The Default materials.xml tree density is 4000m^2, or a tree per
> 63mx63m square (ish). The trees themselves have similar geometric
> complexity to a cuboid (same number of vertices), but buildings don't
> generally have any alpha blending requirements. So to a first level of
> approximation, we should be able to populate the urban area with
> textured cubeoids at the same density as the trees for a similar cost
> performance-wise.
> To provide more interesting buildings, I'm anticipating using a cuboid
> per floor, plus a modified cuboid for the roof, so probably ~ 4x the
> complexity of trees geometrically for a 3 storey building.  Obviously
> there would be XML controls in materials.xml (or a linked XML file)
> for the length, width, number of floors, textures, and roof.
> At the same time, I'm anticipating aligning the buildings with the
> texture, and probably using a second texture as a mask to indicate
> where buildings may, or may not, be placed. This latter technique may
> also have applications for the trees, so that trees only appear a the
> edges of fields, or in the "rough" of golf courses.
> I'm interested in peoples opinions on this, and in particular what
> their view is of the current forest and urban shader performance. It
> may be that my system is unique in that one is cheap and the other
> expensive, and this is all pointless!

Sounds a good idea - I hate the random objects - they are always the wrong
style/size and in the wrong place.

Just do it - we'll make it switchable at runtime. Users can make up their
own minds (or as it has been said of users: what they are pleased to call
their minds).

Looking forward to testing it,


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