VTP photo polygon resolution

General discussion about Scenery Design. Questions about SBuilder for Flight Simulator FS2004.
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JonPatch
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VTP photo polygon resolution

Post by JonPatch » Wed Jun 22, 2005 1:17 am

It's my understanding that the .bmps produced by SBuilder are 8-bit (plus 8-bit alpha if selected). Is this true? Is it possible to get 16-bit?

Speaking of alpha channels, since I only use the alpha channel on the border cells for blending, is there a way to not have alpha on the interior cell .bmps?

Jon
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Luis Sa
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Post by Luis Sa » Wed Jun 22, 2005 3:04 am

Hi,

From the "big" bitmap, SBuilder makes the 256 x 256 bitmaps. SBuilder makes, at a first stage, 32-bit (Red, Green, Blue and Alpha) 256 x 256 pixels bitmaps. Then it calls imagetool to:

1) create the mips
2a) convert to a DXT1 bitmap if all 256 x 256 pixels have ALPHA=0 or
2b) convert to an 8-bit bitmap (with alpha) if at least one pixel has ALPHA different from 0.

If the "big" bitmap has ALPHA=0 in its interior, then the interior slices will automatically be DXT1 (43KB in size). The external ones will be 8-bit with alpha (87KB).

Regards, Luis

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