David Florek (dflorek++at++nvl.army.mil)
Mon, 9 Sep 96 19:31:42 EDT
It does not. To make my life a little easier, I converted the '.obj' to
'.pfa' format instead, and found that the difference was a single token
over a 32MB file, specifically the value for the texture's internal format:
dflorek++at++toltec[135]: head -20 testground_igl.pfa | tail -6
#---------------------- Texture 0
"ground64_512.int"
--> 6 1 1 1 1
0x8010 0x4000 0x4000 0x4000
1 1 1
0.000000 0.000000 0.000000 0.000000
dflorek++at++toltec[136]: head -20 testground_ogl.pfa | tail -6
#---------------------- Texture 0
"ground64_512.int"
--> 4 1 1 1 1
0x8010 0x4000 0x4000 0x4000
1 1 1
0.000000 0.000000 0.000000 0.000000
dflorek++at++toltec[137]:
This corresponds to:
IGL: pfTexFormat(tex, PFTEX_INTERNAL_FORMAT, PFTEX_I_12A_4);
OGL: pfTexFormat(tex, PFTEX_INTERNAL_FORMAT, PFTEX_IA_8);
This appears to be tied to the use of the '.int' texture image format,
as the '.inta' format generates 4 (PFTEX_IA_8) under both IGL and OGL.
Is this in fact a difference in default behavior between IGL and OGL
Performer libraries, when using '.int' formats? Also, will this affect
the appearance of the texture, given that it has no explicit alpha
component? Om this case, the '.int' file in question is 8 bits per
pixel, which is converted to 16 bits of texture information; is
PFTEX_I_12A_4 interpreted as 4 bits of intensity information and 12
bits of alpha, where PFTEX_IA_8 is interpreted as 8 bits of each)?
Would it make more sense for '.int' files to be converted to textures
with PFTEX_I_16 (presumably 16 bits of intensity, no alpha) format?
This might aid in preserving quality during texture filtering....
Any thoughts?
Dave
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David W. Florek EOSoft, Inc. Phone: 703 / 704 - 1767
Senior Engineer NVESD Night Vision Lab Email: dflorek++at++nvl.army.mil
Computer Graphics Ft. Belvoir, VA 22060
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