pfFog to glFog conversion

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Jean-Luc Dery (dery++at++discreet.com)
Thu, 19 Nov 1998 17:33:08 -0500

Hi pfFriends,

I'm trying to figger out how Performer converts fog parameters to OpenGL. When
setting pfFog to one of the following types: PFFOG_VTX_EXP, PFFOG_VTX_EXP2,
PFFOG_PIX_EXP, PFFOG_PIX_EXP2, it should convert the opaque range and type
settings to an equivalent density value in order to set OpenGL density
parameter.

It should look something like that:

PFFOG_VTX_EXP and PFFOG_PIX_EXP
-> density = log( something ) / opaque_range;

PFFOG_VTX_EXP2 and PFFOG_PIX_EXP2
-> density = sqrt( log( something ) ) / opaque_range;

And set OpenGL glFogf( GL_FOG_DENSITY, density ) which is supposed to be used
for these fog types.

Does anybody know what the "something" is and the logic behing it.

Thanks in advance for any help.

Jean-Luc

-- 
_____________________________________________________________________________


Jean-Luc Dery                         Discreet Logic
Technical Leader                      10 Duke Street
3-D Graphics Technology and           Montreal (Quebec), Canada, H3C 2L7
Realtime Systems                      Tel: (514) 954-7239
Email: jean-lucD++at++discreet.com         Fax: (514) 393-0110
_____________________________________________________________________________

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