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View Full Version : bad texture quality on a sphere's outside, inside



deccer
03-06-2010, 09:07 AM
hi there,

when you see this texture, wrapped onto a sphere
http://robsen.3dwars.net/qcfEzeUXUmXya3Nyo2ap.jpg
and the very same object again, but camera looks "into" the obj
http://robsen.3dwars.net/2ZKbaozh3Eq5nfMtmnW0.jpg
you can see a difference in the detail of texture
mi/mafilter = GL_NEAREST thats not the point

i wonder if you have an idea how to fix this ... i want the texture look nice on the outside as on inside...

i tried to flip the normals - no success
i tried to turn off mipmaps by not using either gluBuild*/glGenerateMipMaps or glTexParameteri *_GENERATRE_MIPMAP_* - no success

maybe you have an idea :(

thx in advance

dorbie
03-06-2010, 10:56 AM
Winding does not affect texture filtering. Quality is the same inside and out.

What you are seeing is the difference between the projections.

On the inside view the projected texel size on screen is smaller because the field of view is much larger that when inside the sphere.

deccer
03-06-2010, 02:21 PM
i understand what you mean, but it still makes no sense to me, since there is no change when i try to modify the projection by narrowing/widen the focallength, scenescale, other perspective parameters......

is there any way to make it look like this
http://planetpixelemporium.com/images/fullsize/923jupiter.jpg

hmm i doubt it that i have to use 4096x1024 textures to accomplish this

unless you say im wrong :(

dorbie
03-06-2010, 08:46 PM
Backface vs. frontface does NOT affect texture quality.

Your latest image did not work, I get a permission error reading it.

When you are inside the sphere your FOV is wider and the "red spot" is smaller on screen so you to not see magnification artifacts from individual texels as rectangles.

You could try to use GL_LINEAR filters for magnification and minification filters instead of GL_NEAREST.

deccer
03-07-2010, 04:20 AM
of course it does not affect quality..

http://planetpixelemporium.com/jupiter.html (you can click the jupiter pics to get a little larger version) (possible that raytracing technique was used there...)

i wrote that filtering doesnt affect the quality (of course it does but not that quality i wanted) (same for iso/anisotropic filtering)

i guess ill switch to huge textures :) :(

anyway thanks for your help