Re: [Flightgear-devel] Mipmapping of liveries

[Gary N. <gr...@gm...>]

On Wed, Sep 25, 2013 at 4:46 PM, Tomash Brechko
<tom...@gm...> wrote:
> 100 / cos(45), but you get the idea ;)


OK, I see what you're getting at now-- the selection of the mipmap for
rendering rather than the memory footprint. Yes, that makes sense to
me-- the engine should be able to choose a mipmap that best fits the
screen scale based on distance, so for a larger base image it's
dropping down deeper into the mipmaps.

There is still the issue of resources. A 4096x4096 texture without an
alpha channel is about 50MB, a 1024x1024 is about 3MB. Add +33% for
mipmaps. So a single 4096 texture would buy a lot of 1024's. Also, I
believe the larger the image, the more initial overhead is necessary
to create the mipmaps, unless the image is a DDS type in which case
mipmaps can be pre-generated. So the larger the image, the more memory
resources required, and there's a bigger load hit when the resources
are initially loaded. I've felt my machine come to a crawl while
certain planes are loaded in MP-- I had to remove some because they
were too much of a hit for my poor aging system.

-Gary