Jonas Andersson (jonasa++at++cs.umu.se)
Tue, 1 Dec 1998 13:04:40 +0100 (MET)
> Jonas Andersson wrote:
> >
> > Hi pfAll,
> >
> > With Multigen I have created a square with a texture that is
> > smoothly fading from black to transparent.
> >
> > When loading it with perfly however, it looks like each pixel of the
> > texture is fading "in the opposite direction" of the fading texture.
> >
> > The result is vertical stripes, each stripe being more transparent than
> > itīs left neighbor, but each stripe being more transparent to the
> > left than to the right.
> >
>
> Hi
>
> Your texture has alpha decreasing left->right so you'd expect to see
> transparency increasing left->right ( alpha is the inverse of
> transparency ). ( You can look at this in imgview, get the magnifier
> window up and move along your texture to see alpha decreasing ). If you
> get imgview ( or any other tool ) to flip your texture horizontally then
> in perfly the transparency decreases left->right.
Ooops, got it wrong there. Sorry I meant alpha, not transparancy. This is
not my problem though (see below).
> The banding will be down to performer's internal texture storage, from
> man pftexture:
It seems to me that each band/stripe is not uniform, but has a changing
alpha value. This change is in the opposite direction of the texture. So
if my texture has alpha decreasing left->right then each band has alpha
decreasing right->left and vs.
At first I thought this had something to do with filtering, but changing
it in Multigen makes no difference in perfly.
Any idea anyone?
>
> ...
> pfTexture::setFormat
> ...
> PFTEX_I_12A_4 16-bit texels. The default 2 component
> internal format.
>
> So you need to force performer to use more bits to store the I_A info
> you have with say PFTEX_IA_12
>
> Cheers
> Rob
>
>
> > It seems to me there are some kind of property I could use to fix this
> > problem, but I donīt know which. If you know, please let me know...
> >
> > Example files are attached in fadetest.tar.
> >
> > Thankīs in advance for any help.
> >
> > -- Jonas
> > ________________________________________________________________________________
> > Jonas Andersson jonasa++at++acc.umu.se, http://www.cs.umu.se/~jonasa
> >
> > ------------------------------------------------------------------------
> >
> > Name: fadetest.tar
> > fadetest.tar Type: Unix Tape Archive (APPLICATION/x-tar)
> > Encoding: BASE64
>
> --
> ________________________________________________________________
> Rob Jenkins Silicon Graphics mailto:robj++at++sgi.com
>
-- Jonas
________________________________________________________________________________
Jonas Andersson jonasa++at++acc.umu.se, http://www.cs.umu.se/~jonasa
This archive was generated by hypermail 2.0b2 on Tue Dec 01 1998 - 04:04:51 PST