Re: Custom texture filtering

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Rémi Arnaud (remi++at++remi.asd.sgi.com)
Tue, 14 Jan 1997 16:31:48 -0800 (PST)


Gilles Reymond wrote:
>
> Hi,
>
> Has anyone some experience with gltexfilterfuncsgis - or its IrisGl counterpart
> texdef2d(TX_MIPMAP_FILTER_KERNEL) ?
  
  Warning: this filter option has a cost of 2X in fill.

>
> My particular problem is to deal with a repeated RGBA texture mapped onto a
> polygon strip going away to the horizon. Using mipmapping
> GL_LINEAR_MIPMAP_LINEAR causes some artifacts in the rendering of the farthest
> side of the object, where the min_filter supposedly becomes active. I guess this
> is due to the particular structure of the texture.
> This effect was experienced both on iR and RE2 systems, though with slight
> rendering aspect differences.
>
> Hence, my questions are :
>
> - was is the weighting policy used by standard trilinear mipmapping on
> those systems ?
> - would a custom-designed set of weights help solve my problem ?
> - what is the recommended method for chosing these weights (through
> Performer calls, maybe)?
>

 The first thing you should do is to provide your own texture LOD, instead of using
 the default ones. So you could remove some high frequency you have in the smallest
 LODs.

 Unfortunately for you, this is available only with OpenGL.

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