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Date: Mon, 31 Mar 2003 15:45:02 -0500
From: Mark Montana <pat...@lm...>
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To: gl4...@li...
CC: Pepijn Van Eeckhoudt <pep...@lu...>
Subject: FYI...Solved my dark texture problem
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In case anyone has this texturing problem in the future, here was my solution...

I reverted back to using GL_BLEND mode for the texturing. The equation that OpenGL uses in this mode (for an RGB texture) is:
C = Cf(1-Ct) + Cc*Ct

where
Cf = the existing fragment color (underlying polygon color)
Ct = the texel color (texture image in that position)
Cc = is a blend color you can set for texturing

At first I set Cf and Cc to pure white (hoping to get the brightening effect I wanted). However, I got no texture, only pure
white polygons. From the equation above, I could have predicted this, since the Ct components completely cancel out when Cf =
Cc. Therefore, I was only left with Cf in the equation.

As a solution, I set Cf (the polygon color) to (0.15, 0.15, 0.15, 1.0), and I set Cc (the blend color) to (1.0, 1.0, 1.0, 1.0).
This gave me nice results with the lightening I was looking for.

Thanks again for the feedback I received. This mailing list is a great resource.

-Mark

Pepijn Van Eeckhoudt wrote:

> > (4) Back to the textures being too dark. I am currently using MODULATE, and
> > the underlying color is pure white (again, 2D, no lighting, no normals). The
> > texture is still too dark. The same texture looks good in our Java3D display,
> > because we are using a Java3D mechanism related to combining fragments and
> > anisotropic filtering. In the GL4Java side, I decided to give the BLEND
> > texture mode a try. When I use that, I only get the pure blend color (no
> > texture). I enabled blending and I used glBlendFunc() to play with the
> > blending methods. (I would supply some sample code here, but I already
> > deleted that failed attempt.)
> >
>
> What happens when you use REPLACE? And if you disable the texture, is
> the polygon pure white?
>
> Pepijn
>
> > Thanks again for any advice.
> > -Mark
> >
> >
>
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