Spark really loves its pointless decimals everywhere

AlignAlign Remain Calm Join Date: 2002-11-02 Member: 5216Forum Moderators, Constellation
in NS2 General Discussion
<div class="IPBDescription">no pun intended</div>When I set a texture to be scale 0.2, it'll be like 0.19992587 when I check it five seconds later. What gives?
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  • w0dk4w0dk4 Join Date: 2008-04-22 Member: 64129Members, Constellation, Reinforced - Shadow
    ever heard about floating point (un)precision?
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  • PrivatePrivate Join Date: 2007-06-10 Member: 61204Members, Constellation
    Well, I guess it's down to rounding errors and floating point precision. Hit up a wikipedia article for more on that.

    This happens when you modify your geometry with texture lock enabled (little blue padlock, right bottom). Say you move a vertex. Spark recognizes that you changed the face, and since texture lock is enabled it will attempt to keep the texture in place on the face. Stretching, moving, or rotating the texture to make it stay where it was. In the process, small errors are introduced by the floating point operations. You then change you mind, press undo or move the vertex back manually. The old state is not remembered though. The operations are just performed in reverse order. And as they are performed on data with slight errors, you will see those .976E-6 displacements on your faces, even though you didn't mean to change anything at all.

    At least, that's how I think it's working. I usually disable texture lock, it seems to take care of most of it.
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  • TerrTerr Arthritic Skulk Join Date: 2002-11-07 Member: 7486Members
    I would like to chime in that there are times I wished I could scale a texture in Hammer to some level of precision much greater than the dialog allows you to. You sort of can, but it forgets and rounds your entry when you go back, so applying the same scaling to multiple faces can get annoying.
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  • AlignAlign Remain Calm Join Date: 2002-11-02 Member: 5216Forum Moderators, Constellation
    So it had the reverse problem? Huh.
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  • TerrTerr Arthritic Skulk Join Date: 2002-11-07 Member: 7486Members
    Well, I wanted to get some complex geometry to line up, and I was dealing with rotation and scaling... And Apparently if 0.43 is just the right amount, then whenever you return to the texture it gets rounded to 0.45, and the next time you click "Apply" it'll sneakily undo your carefully-tuned value...
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