gluBuild2DMidmaps and existing Texture-Object

I was wondering if there is a way to apply gluBuildmMidmpas on a existing Texture-Object. The only thing i have is the OpenGL-Texture name .


As the glu thingy probably makes just some calles to glTexturexd i wouldn’t think it would be possible to apply it. I currently don’t see any other way than downloading the texture.

problem is that i am extracting my textures from real camera pix, and have them already stored as textures and would love to use SGIS_generate_midmap on them (as soon as the new linux driver is released ) and in the mean time just use the gluBuildMidmaps

Yeah, I get what you mean. Don’t know any clue for that. Is it for visual reasons or for performance?

for visual reasons and analysing. During the texture extraction i am setting the alphas to 0 of all the ares which are occluded and know i want to know which texture has and occluded area and which one doesn’t. Therefore I thought about having a 1x1 texture which i could read fast out of the back buffer and check the resulting alpha value. The prob is that ia not sure how OpenGL interpolates the alpha values when ia drwing a 128x128 texture on a one pixel-size square. I think with using gluBuildMidmaps the alpha values for a 1x1 Texture are interpolated correctly.